The stability of a chemical compound is eventually limited when exposed to extreme environmental conditions such as heat, radiation, humidity, or the acidity of a solvent. Because of this chemical decomposition is often an undesired chemical reaction. However chemical decomposition can be desired, such as in various waste treatment processes.
https://en.wikipedia.org/wiki/Chemical_decomposition
Energy storage is the capture of energy produced at one time for use at a later time[1] to reduce imbalances between energy demand and energy production. A device that stores energy is generally called an accumulator or battery. Energy comes in multiple forms including radiation, chemical, gravitational potential, electrical potential, electricity, elevated temperature, latent heat and kinetic. Energy storage involves converting energy from forms that are difficult to store to more conveniently or economically storable forms.
Some technologies provide short-term energy storage, while others can endure for much longer. Bulk energy storage is currently dominated by hydroelectric dams, both conventional as well as pumped. Grid energy storage is a collection of methods used for energy storage on a large scale within an electrical power grid.
Common examples of energy storage are the rechargeable battery, which stores chemical energy readily convertible to electricity to operate a mobile phone; the hydroelectric dam, which stores energy in a reservoir as gravitational potential energy; and ice storage tanks, which store ice frozen by cheaper energy at night to meet peak daytime demand for cooling. Green hydrogen, from electrolysis of water, is a more economical means of long-term renewable energy storage in terms of capital expenditures than pumped-storage hydroelectricity or batteries.[2][3] Fossil fuels such as coal and gasoline store ancient energy derived from sunlight by organisms that later died, became buried and over time were then converted into these fuels. Food (which is made by the same process as fossil fuels) is a form of energy stored in chemical form.
History
In the 20th century grid, electrical power was largely generated by burning fossil fuel. When less power was required, less fuel was burned.[4] Hydropower, a mechanical energy storage method, is the most widely adopted mechanical energy storage, and has been in use for centuries. Large hydropower dams have been energy storage sites for more than one hundred years.[5] Concerns with air pollution, energy imports, and global warming have spawned the growth of renewable energy such as solar and wind power.[4] Wind power is uncontrolled and may be generating at a time when no additional power is needed. Solar power varies with cloud cover and at best is only available during daylight hours, while demand often peaks after sunset (see duck curve). Interest in storing power from these intermittent sources grows as the renewable energy industry begins to generate a larger fraction of overall energy consumption.[6]
Off grid electrical use was a niche market in the 20th century, but in the 21st century, it has expanded. Portable devices are in use all over the world. Solar panels are now common in the rural settings worldwide. Access to electricity is now a question of economics and financial viability, and not solely on technical aspects. Electric vehicles are gradually replacing combustion-engine vehicles. However, powering long-distance transportation without burning fuel remains in development.
Methods
Outline
The following list includes a variety of types of energy storage:
- Fossil fuel storage
- Mechanical
- Spring
- Compressed air energy storage (CAES)
- Fireless locomotive
- Flywheel energy storage
- Solid mass gravitational
- Hydraulic accumulator
- Pumped-storage hydroelectricity (pumped hydroelectric storage, PHS, or pumped storage hydropower, PSH)
- Thermal Expansion
- Electrical, electromagnetic
- Capacitor
- Supercapacitor
- Superconducting magnetic energy storage (SMES, also superconducting storage coil)
- Biological
- Electrochemical (Battery Energy Storage System, BESS)
- Thermal
- Chemical
Mechanical
Energy can be stored in water pumped to a higher elevation using pumped storage methods or by moving solid matter to higher locations (gravity batteries). Other commercial mechanical methods include compressing air and flywheels that convert electric energy into internal energy or kinetic energy and then back again when electrical demand peaks.
Hydroelectricity
Hydroelectric dams with reservoirs can be operated to provide electricity at times of peak demand. Water is stored in the reservoir during periods of low demand and released when demand is high. The net effect is similar to pumped storage, but without the pumping loss.
While a hydroelectric dam does not directly store energy from other generating units, it behaves equivalently by lowering output in periods of excess electricity from other sources. In this mode, dams are one of the most efficient forms of energy storage, because only the timing of its generation changes. Hydroelectric turbines have a start-up time on the order of a few minutes.[7]
Pumped hydro
Worldwide, pumped-storage hydroelectricity (PSH) is the largest-capacity form of active grid energy storage available, and, as of March 2012, the Electric Power Research Institute (EPRI) reports that PSH accounts for more than 99% of bulk storage capacity worldwide, representing around 127,000 MW.[8] PSH energy efficiency varies in practice between 70% and 80%,[8][9][10][11] with claims of up to 87%.[12]
At times of low electrical demand, excess generation capacity is used to pump water from a lower source into a higher reservoir. When demand grows, water is released back into a lower reservoir (or waterway or body of water) through a turbine, generating electricity. Reversible turbine-generator assemblies act as both a pump and turbine (usually a Francis turbine design). Nearly all facilities use the height difference between two water bodies. Pure pumped-storage plants shift the water between reservoirs, while the "pump-back" approach is a combination of pumped storage and conventional hydroelectric plants that use natural stream-flow.
Compressed air
Compressed air energy storage (CAES) uses surplus energy to compress air for subsequent electricity generation.[13] Small-scale systems have long been used in such applications as propulsion of mine locomotives. The compressed air is stored in an underground reservoir, such as a salt dome.
Compressed-air energy storage (CAES) plants can bridge the gap between production volatility and load. CAES storage addresses the energy needs of consumers by effectively providing readily available energy to meet demand. Renewable energy sources like wind and solar energy vary. So at times when they provide little power, they need to be supplemented with other forms of energy to meet energy demand. Compressed-air energy storage plants can take in the surplus energy output of renewable energy sources during times of energy over-production. This stored energy can be used at a later time when demand for electricity increases or energy resource availability decreases.[14]
Compression of air creates heat; the air is warmer after compression. Expansion requires heat. If no extra heat is added, the air will be much colder after expansion. If the heat generated during compression can be stored and used during expansion, efficiency improves considerably.[15] A CAES system can deal with the heat in three ways. Air storage can be adiabatic, diabatic, or isothermal. Another approach uses compressed air to power vehicles.[16][17]
Flywheel
Flywheel energy storage (FES) works by accelerating a rotor (a flywheel) to a very high speed, holding energy as rotational energy. When energy is added the rotational speed of the flywheel increases, and when energy is extracted, the speed declines, due to conservation of energy.
Most FES systems use electricity to accelerate and decelerate the flywheel, but devices that directly use mechanical energy are under consideration.[18]
FES systems have rotors made of high strength carbon-fiber composites, suspended by magnetic bearings and spinning at speeds from 20,000 to over 50,000 revolutions per minute (rpm) in a vacuum enclosure.[19] Such flywheels can reach maximum speed ("charge") in a matter of minutes. The flywheel system is connected to a combination electric motor/generator.
FES systems have relatively long lifetimes (lasting decades with little or no maintenance;[19] full-cycle lifetimes quoted for flywheels range from in excess of 105, up to 107, cycles of use),[20] high specific energy (100–130 W·h/kg, or 360–500 kJ/kg)[20][21] and power density.
Solid mass gravitational
Changing the altitude of solid masses can store or release energy via an elevating system driven by an electric motor/generator. Studies suggest energy can begin to be released with as little as 1 second warning, making the method a useful supplemental feed into an electricity grid to balance load surges.[22]
Efficiencies can be as high as 85% recovery of stored energy.[23]
This can be achieved by siting the masses inside old vertical mine shafts or in specially constructed towers where the heavy weights are winched up to store energy and allowed a controlled descent to release it. At 2020 a prototype vertical store is being built in Edinburgh, Scotland [24]
Potential energy storage or gravity energy storage was under active development in 2013 in association with the California Independent System Operator.[25][26][27] It examined the movement of earth-filled hopper rail cars driven by electric locomotives from lower to higher elevations.[28]
Other proposed methods include:-
- using rails,[28][29] cranes,[23] or elevators[30] to move weights up and down;
- using high-altitude solar-powered balloon platforms supporting winches to raise and lower solid masses slung underneath them,[31]
- using winches supported by an ocean barge to take advantage of a 4 km (13,000 ft) elevation difference between the sea surface and the seabed,[32]
Thermal
Thermal energy storage (TES) is the temporary storage or removal of heat.
Sensible heat thermal
Sensible heat storage take advantage of sensible heat in a material to store energy.[33]
Seasonal thermal energy storage (STES) allows heat or cold to be used months after it was collected from waste energy or natural sources. The material can be stored in contained aquifers, clusters of boreholes in geological substrates such as sand or crystalline bedrock, in lined pits filled with gravel and water, or water-filled mines.[34] Seasonal thermal energy storage (STES) projects often have paybacks in four to six years.[35] An example is Drake Landing Solar Community in Canada, for which 97% of the year-round heat is provided by solar-thermal collectors on garage roofs, enabled by a borehole thermal energy store (BTES).[36][37][38] In Braedstrup, Denmark, the community's solar district heating system also uses STES, at a temperature of 65 °C (149 °F). A heat pump, which runs only while surplus wind power is available. It is used to raise the temperature to 80 °C (176 °F) for distribution. When wind energy is not available, a gas-fired boiler is used. Twenty percent of Braedstrup's heat is solar.[39]
Latent heat thermal (LHTES)
Latent heat thermal energy storage systems work by transferring heat to or from a material to change its phase. A phase-change is the melting, solidifying, vaporizing or liquifying. Such a material is called a phase change material (PCM). Materials used in LHTESs often have a high latent heat so that at their specific temperature, the phase change absorbs a large amount of energy, much more than sensible heat.[40]
A steam accumulator is a type of LHTES where the phase change is between liquid and gas and uses the latent heat of vaporization of water. Ice storage air conditioning systems use off-peak electricity to store cold by freezing water into ice. The stored cold in ice releases during melting process and can be used for cooling at peak hours.
Cryogenic thermal energy storage
Air can be liquefied by cooling using electricity and stored as a cryogen with existing technologies. The liquid air can then be expanded through a turbine and the energy recovered as electricity. The system was demonstrated at a pilot plant in the UK in 2012.[41] In 2019, Highview announced plans to build a 50 MW in the North of England and northern Vermont, with the proposed facility able to store five to eight hours of energy, for a 250-400 MWh storage capacity.[42]
Carnot battery
Electrical energy can be stored thermally by resistive heating or heat pumps, and the stored heat can be converted back to electricity via Rankine cycle or Brayton cycle.[43] This technology has been studied to retrofit coal-fired power plants into fossil-fuel free generation systems.[44] Coal-fired boilers are replaced by high-temperature heat storage charged by excess electricity from renewable energy sources. In 2020, German Aerospace Center started to construct the world's first large-scale Carnot battery system, which has 1,000 MWh storage capacity.[45]
Electrochemical
Rechargeable battery
A rechargeable battery comprises one or more electrochemical cells. It is known as a 'secondary cell' because its electrochemical reactions are electrically reversible. Rechargeable batteries come in many shapes and sizes, ranging from button cells to megawatt grid systems.
Rechargeable batteries have lower total cost of use and environmental impact than non-rechargeable (disposable) batteries. Some rechargeable battery types are available in the same form factors as disposables. Rechargeable batteries have higher initial cost but can be recharged very cheaply and used many times.
Common rechargeable battery chemistries include:
- Lead–acid battery: Lead acid batteries hold the largest market share of electric storage products. A single cell produces about 2V when charged. In the charged state the metallic lead negative electrode and the lead sulfate positive electrode are immersed in a dilute sulfuric acid (H2SO4) electrolyte. In the discharge process electrons are pushed out of the cell as lead sulfate is formed at the negative electrode while the electrolyte is reduced to water.
- Lead-acid battery technology has been developed extensively. Upkeep requires minimal labor and its cost is low. The battery's available energy capacity is subject to a quick discharge resulting in a low life span and low energy density.[46]
- Nickel–cadmium battery (NiCd): Uses nickel oxide hydroxide and metallic cadmium as electrodes. Cadmium is a toxic element, and was banned for most uses by the European Union in 2004. Nickel–cadmium batteries have been almost completely replaced by nickel–metal hydride (NiMH) batteries.
- Nickel–metal hydride battery (NiMH): First commercial types were available in 1989.[47] These are now a common consumer and industrial type. The battery has a hydrogen-absorbing alloy for the negative electrode instead of cadmium.
- Lithium-ion battery: The choice in many consumer electronics and have one of the best energy-to-mass ratios and a very slow self-discharge when not in use.
- Lithium-ion polymer battery: These batteries are light in weight and can be made in any shape desired.
- Aluminium-sulfur battery with rock salt crystals as electrolyte: aluminium and sulfur are Earth-abundant materials and are much more cheaper than traditional Lithium.[48]
Flow battery
A flow battery works by passing a solution over a membrane where ions are exchanged to charge or discharge the cell. Cell voltage is chemically determined by the Nernst equation and ranges, in practical applications, from 1.0 V to 2.2 V. Storage capacity depends on the volume of solution. A flow battery is technically akin both to a fuel cell and an electrochemical accumulator cell. Commercial applications are for long half-cycle storage such as backup grid power.
Supercapacitor
Supercapacitors, also called electric double-layer capacitors (EDLC) or ultracapacitors, are a family of electrochemical capacitors[49] that do not have conventional solid dielectrics. Capacitance is determined by two storage principles, double-layer capacitance and pseudocapacitance.[50][51]
Supercapacitors bridge the gap between conventional capacitors and rechargeable batteries. They store the most energy per unit volume or mass (energy density) among capacitors. They support up to 10,000 farads/1.2 Volt,[52] up to 10,000 times that of electrolytic capacitors, but deliver or accept less than half as much power per unit time (power density).[49]
While supercapacitors have specific energy and energy densities that are approximately 10% of batteries, their power density is generally 10 to 100 times greater. This results in much shorter charge/discharge cycles. Also, they tolerate many more charge-discharge cycles than batteries.
Supercapacitors have many applications, including:
- Low supply current for memory backup in static random-access memory (SRAM)
- Power for cars, buses, trains, cranes and elevators, including energy recovery from braking, short-term energy storage and burst-mode power delivery
Chemical
Power to gas
Power to gas is the conversion of electricity to a gaseous fuel such as hydrogen or methane. The three commercial methods use electricity to reduce water into hydrogen and oxygen by means of electrolysis.
In the first method, hydrogen is injected into the natural gas grid or is used for transportation. The second method is to combine the hydrogen with carbon dioxide to produce methane using a methanation reaction such as the Sabatier reaction, or biological methanation, resulting in an extra energy conversion loss of 8%. The methane may then be fed into the natural gas grid. The third method uses the output gas of a wood gas generator or a biogas plant, after the biogas upgrader is mixed with the hydrogen from the electrolyzer, to upgrade the quality of the biogas.
Hydrogen
The element hydrogen can be a form of stored energy. Hydrogen can produce electricity via a hydrogen fuel cell. Green hydrogen, from electrolysis of water, is a more economical means of long-term renewable energy storage in terms of capital expenditures than pumped-storage hydroelectricity or batteries.[2][3]
At penetrations below 20% of the grid demand, renewables do not severely change the economics; but beyond about 20% of the total demand,[53] external storage becomes important. If these sources are used to make ionic hydrogen, they can be freely expanded. A 5-year community-based pilot program using wind turbines and hydrogen generators began in 2007 in the remote community of Ramea, Newfoundland and Labrador.[54] A similar project began in 2004 on Utsira, a small Norwegian island.
Energy losses involved in the hydrogen storage cycle come from the electrolysis of water, liquification or compression of the hydrogen and conversion to electricity.[55]
About 50 kW·h (180 MJ) of solar energy is required to produce a kilogram of hydrogen, so the cost of the electricity is crucial. At $0.03/kWh, a common off-peak high-voltage line rate in the United States, hydrogen costs $1.50 per kilogram for the electricity, equivalent to $1.50/gallon for gasoline. Other costs include the electrolyzer plant, hydrogen compressors or liquefaction, storage and transportation.[citation needed]
Hydrogen can also be produced from aluminum and water by stripping aluminum's naturally-occurring aluminum oxide barrier and introducing it to water. This method is beneficial because recycled aluminum cans can be used to generate hydrogen, however systems to harness this option have not been commercially developed and are much more complex than electrolysis systems.[56] Common methods to strip the oxide layer include caustic catalysts such as sodium hydroxide and alloys with gallium, mercury and other metals.[57]
Underground hydrogen storage is the practice of hydrogen storage in caverns, salt domes and depleted oil and gas fields.[58][59] Large quantities of gaseous hydrogen have been stored in caverns by Imperial Chemical Industries for many years without any difficulties.[60] The European Hyunder project indicated in 2013 that storage of wind and solar energy using underground hydrogen would require 85 caverns.[61]
Powerpaste is a magnesium and hydrogen -based fluid gel that releases hydrogen when reacting with water. It was invented, patented and is being developed by the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) of the Fraunhofer-Gesellschaft. Powerpaste is made by combining magnesium powder with hydrogen to form magnesium hydride in a process conducted at 350 °C and five to six times atmospheric pressure. An ester and a metal salt are then added to make the finished product. Fraunhofer states that they are building a production plant slated to start production in 2021, which will produce 4 tons of Powerpaste annually.[62] Fraunhofer has patented their invention in the United States and EU.[63] Fraunhofer claims that Powerpaste is able to store hydrogen energy at 10 times the energy density of a lithium battery of a similar dimension and is safe and convenient for automotive situations.[62]
Methane
Methane is the simplest hydrocarbon with the molecular formula CH4. Methane is more easily stored and transported than hydrogen. Storage and combustion infrastructure (pipelines, gasometers, power plants) are mature.
Synthetic natural gas (syngas or SNG) can be created in a multi-step process, starting with hydrogen and oxygen. Hydrogen is then reacted with carbon dioxide in a Sabatier process, producing methane and water. Methane can be stored and later used to produce electricity. The resulting water is recycled, reducing the need for water. In the electrolysis stage, oxygen is stored for methane combustion in a pure oxygen environment at an adjacent power plant, eliminating nitrogen oxides.
Methane combustion produces carbon dioxide (CO2) and water. The carbon dioxide can be recycled to boost the Sabatier process and water can be recycled for further electrolysis. Methane production, storage and combustion recycles the reaction products.
The CO2 has economic value as a component of an energy storage vector, not a cost as in carbon capture and storage.
Power to liquid
Power to liquid is similar to power to gas except that the hydrogen is converted into liquids such as methanol or ammonia. These are easier to handle than gases, and requires fewer safety precautions than hydrogen. They can be used for transportation, including aircraft, but also for industrial purposes or in the power sector.[64]
Biofuels
Various biofuels such as biodiesel, vegetable oil, alcohol fuels, or biomass can replace fossil fuels. Various chemical processes can convert the carbon and hydrogen in coal, natural gas, plant and animal biomass and organic wastes into short hydrocarbons suitable as replacements for existing hydrocarbon fuels. Examples are Fischer–Tropsch diesel, methanol, dimethyl ether and syngas. This diesel source was used extensively in World War II in Germany, which faced limited access to crude oil supplies. South Africa produces most of the country's diesel from coal for similar reasons.[65] A long term oil price above US$35/bbl may make such large scale synthetic liquid fuels economical.
Aluminum
Aluminum has been proposed as an energy store by a number of researchers. Its electrochemical equivalent (8.04 Ah/cm3) is nearly four times greater than that of lithium (2.06 Ah/cm3).[66] Energy can be extracted from aluminum by reacting it with water to generate hydrogen.[67] However, it must first be stripped of its natural oxide layer, a process which requires pulverization,[68] chemical reactions with caustic substances, or alloys.[57] The byproduct of the reaction to create hydrogen is aluminum oxide, which can be recycled into aluminum with the Hall–Héroult process, making the reaction theoretically renewable.[57] If the Hall-Heroult Process is run using solar or wind power, aluminum could be used to store the energy produced at higher efficiency than direct solar electrolysis.[69]
Boron, silicon, and zinc
Boron,[70] silicon,[71] and zinc[72] have been proposed as energy storage solutions.
Other chemical
The organic compound norbornadiene converts to quadricyclane upon exposure to light, storing solar energy as the energy of chemical bonds. A working system has been developed in Sweden as a molecular solar thermal system.[73]
Electrical methods
Capacitor
A capacitor (originally known as a 'condenser') is a passive two-terminal electrical component used to store energy electrostatically. Practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e., insulator). A capacitor can store electric energy when disconnected from its charging circuit, so it can be used like a temporary battery, or like other types of rechargeable energy storage system.[74] Capacitors are commonly used in electronic devices to maintain power supply while batteries change. (This prevents loss of information in volatile memory.) Conventional capacitors provide less than 360 joules per kilogram, while a conventional alkaline battery has a density of 590 kJ/kg.
Capacitors store energy in an electrostatic field between their plates. Given a potential difference across the conductors (e.g., when a capacitor is attached across a battery), an electric field develops across the dielectric, causing positive charge (+Q) to collect on one plate and negative charge (-Q) to collect on the other plate. If a battery is attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if an accelerating or alternating voltage is applied across the leads of the capacitor, a displacement current can flow. Besides capacitor plates, charge can also be stored in a dielectric layer.[75]
Capacitance is greater given a narrower separation between conductors and when the conductors have a larger surface area. In practice, the dielectric between the plates emits a small amount of leakage current and has an electric field strength limit, known as the breakdown voltage. However, the effect of recovery of a dielectric after a high-voltage breakdown holds promise for a new generation of self-healing capacitors.[76][77] The conductors and leads introduce undesired inductance and resistance.
Research is assessing the quantum effects of nanoscale capacitors[78] for digital quantum batteries.[79][80]
Superconducting magnetics
Superconducting magnetic energy storage (SMES) systems store energy in a magnetic field created by the flow of direct current in a superconducting coil that has been cooled to a temperature below its superconducting critical temperature. A typical SMES system includes a superconducting coil, power conditioning system and refrigerator. Once the superconducting coil is charged, the current does not decay and the magnetic energy can be stored indefinitely.[81]
The stored energy can be released to the network by discharging the coil. The associated inverter/rectifier accounts for about 2–3% energy loss in each direction. SMES loses the least amount of electricity in the energy storage process compared to other methods of storing energy. SMES systems offer round-trip efficiency greater than 95%.[82]
Due to the energy requirements of refrigeration and the cost of superconducting wire, SMES is used for short duration storage such as improving power quality. It also has applications in grid balancing.[81]
Applications
Mills
The classic application before the industrial revolution was the control of waterways to drive water mills for processing grain or powering machinery. Complex systems of reservoirs and dams were constructed to store and release water (and the potential energy it contained) when required.[83]
Homes
Home energy storage is expected to become increasingly common given the growing importance of distributed generation of renewable energies (especially photovoltaics) and the important share of energy consumption in buildings.[84] To exceed a self-sufficiency of 40% in a household equipped with photovoltaics, energy storage is needed.[84] Multiple manufacturers produce rechargeable battery systems for storing energy, generally to hold surplus energy from home solar or wind generation. Today, for home energy storage, Li-ion batteries are preferable to lead-acid ones given their similar cost but much better performance.[85]
Tesla Motors produces two models of the Tesla Powerwall. One is a 10 kWh weekly cycle version for backup applications and the other is a 7 kWh version for daily cycle applications.[86] In 2016, a limited version of the Tesla Powerpack 2 cost $398(US)/kWh to store electricity worth 12.5 cents/kWh (US average grid price) making a positive return on investment doubtful unless electricity prices are higher than 30 cents/kWh.[87]
RoseWater Energy produces two models of the "Energy & Storage System", the HUB 120[88] and SB20.[89] Both versions provide 28.8 kWh of output, enabling it to run larger houses or light commercial premises, and protecting custom installations. The system provides five key elements into one system, including providing a clean 60 Hz Sine wave, zero transfer time, industrial-grade surge protection, renewable energy grid sell-back (optional), and battery backup.[90][91]
Enphase Energy announced an integrated system that allows home users to store, monitor and manage electricity. The system stores 1.2 kWh of energy and 275W/500W power output.[92]
Storing wind or solar energy using thermal energy storage though less flexible, is considerably cheaper than batteries. A simple 52-gallon electric water heater can store roughly 12 kWh of energy for supplementing hot water or space heating.[93]
For purely financial purposes in areas where net metering is available, home generated electricity may be sold to the grid through a grid-tie inverter without the use of batteries for storage.
Grid electricity and power stations
Renewable energy
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The largest source and the greatest store of renewable energy is provided by hydroelectric dams. A large reservoir behind a dam can store enough water to average the annual flow of a river between dry and wet seasons. A very large reservoir can store enough water to average the flow of a river between dry and wet years. While a hydroelectric dam does not directly store energy from intermittent sources, it does balance the grid by lowering its output and retaining its water when power is generated by solar or wind. If wind or solar generation exceeds the region's hydroelectric capacity, then some additional source of energy is needed.
Many renewable energy sources (notably solar and wind) produce variable power.[98] Storage systems can level out the imbalances between supply and demand that this causes. Electricity must be used as it is generated or converted immediately into storable forms.[99]
The main method of electrical grid storage is pumped-storage hydroelectricity. Areas of the world such as Norway, Wales, Japan and the US have used elevated geographic features for reservoirs, using electrically powered pumps to fill them. When needed, the water passes through generators and converts the gravitational potential of the falling water into electricity.[98] Pumped storage in Norway, which gets almost all its electricity from hydro, has currently a capacity of 1.4 GW but since the total installed capacity is nearly 32 GW and 75% of that is regulable, it can be expanded significantly.[100]
Some forms of storage that produce electricity include pumped-storage hydroelectric dams, rechargeable batteries, thermal storage including molten salts which can efficiently store and release very large quantities of heat energy,[101] and compressed air energy storage, flywheels, cryogenic systems and superconducting magnetic coils.
Surplus power can also be converted into methane (sabatier process) with stockage in the natural gas network.[102][103]
In 2011, the Bonneville Power Administration in Northwestern United States created an experimental program to absorb excess wind and hydro power generated at night or during stormy periods that are accompanied by high winds. Under central control, home appliances absorb surplus energy by heating ceramic bricks in special space heaters to hundreds of degrees and by boosting the temperature of modified hot water heater tanks. After charging, the appliances provide home heating and hot water as needed. The experimental system was created as a result of a severe 2010 storm that overproduced renewable energy to the extent that all conventional power sources were shut down, or in the case of a nuclear power plant, reduced to its lowest possible operating level, leaving a large area running almost completely on renewable energy.[104][105]
Another advanced method used at the former Solar Two project in the United States and the Solar Tres Power Tower in Spain uses molten salt to store thermal energy captured from the sun and then convert it and dispatch it as electrical power. The system pumps molten salt through a tower or other special conduits to be heated by the sun. Insulated tanks store the solution. Electricity is produced by turning water to steam that is fed to turbines.
Since the early 21st century batteries have been applied to utility scale load-leveling and frequency regulation capabilities.[98]
In vehicle-to-grid storage, electric vehicles that are plugged into the energy grid can deliver stored electrical energy from their batteries into the grid when needed.
Air conditioning
Thermal energy storage (TES) can be used for air conditioning.[106] It is most widely used for cooling single large buildings and/or groups of smaller buildings. Commercial air conditioning systems are the biggest contributors to peak electrical loads. In 2009, thermal storage was used in over 3,300 buildings in over 35 countries. It works by chilling material at night and using the chilled material for cooling during the hotter daytime periods.[101]
The most popular technique is ice storage, which requires less space than water and is cheaper than fuel cells or flywheels. In this application, a standard chiller runs at night to produce an ice pile. Water circulates through the pile during the day to chill water that would normally be the chiller's daytime output.
A partial storage system minimizes capital investment by running the chillers nearly 24 hours a day. At night, they produce ice for storage and during the day they chill water. Water circulating through the melting ice augments the production of chilled water. Such a system makes ice for 16 to 18 hours a day and melts ice for six hours a day. Capital expenditures are reduced because the chillers can be just 40% - 50% of the size needed for a conventional, no-storage design. Storage sufficient to store half a day's available heat is usually adequate.
A full storage system shuts off the chillers during peak load hours. Capital costs are higher, as such a system requires larger chillers and a larger ice storage system.
This ice is produced when electrical utility rates are lower.[107] Off-peak cooling systems can lower energy costs. The U.S. Green Building Council has developed the Leadership in Energy and Environmental Design (LEED) program to encourage the design of reduced-environmental impact buildings. Off-peak cooling may help toward LEED Certification.[108]
Thermal storage for heating is less common than for cooling. An example of thermal storage is storing solar heat to be used for heating at night.
Latent heat can also be stored in technical phase change materials (PCMs). These can be encapsulated in wall and ceiling panels, to moderate room temperatures.
Transport
Liquid hydrocarbon fuels are the most commonly used forms of energy storage for use in transportation, followed by a growing use of Battery Electric Vehicles and Hybrid Electric Vehicles. Other energy carriers such as hydrogen can be used to avoid producing greenhouse gases.
Public transport systems like trams and trolleybuses require electricity, but due to their variability in movement, a steady supply of electricity via renewable energy is challenging. Photovoltaic systems installed on the roofs of buildings can be used to power public transportation systems during periods in which there is increased demand for electricity and access to other forms of energy are not readily available.[109] Upcoming transitions in the transportation system also include e.g. ferries and airplanes, where electric power supply is investigated as an interesting alternative.[110]
Electronics
Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies. In resonant circuits they tune radios to particular frequencies. In electric power transmission systems they stabilize voltage and power flow.[111]
Use cases
The United States Department of Energy International Energy Storage Database (IESDB), is a free-access database of energy storage projects and policies funded by the United States Department of Energy Office of Electricity and Sandia National Labs.[112]
Capacity
Storage capacity is the amount of energy extracted from an energy storage device or system; usually measured in joules or kilowatt-hours and their multiples, it may be given in number of hours of electricity production at power plant nameplate capacity; when storage is of primary type (i.e., thermal or pumped-water), output is sourced only with the power plant embedded storage system.[113][114]
Economics
The economics of energy storage strictly depends on the reserve service requested, and several uncertainty factors affect the profitability of energy storage. Therefore, not every storage method is technically and economically suitable for the storage of several MWh, and the optimal size of the energy storage is market and location dependent.[115]
Moreover, ESS are affected by several risks, e.g.:[116]
- Techno-economic risks, which are related to the specific technology;
- Market risks, which are the factors that affect the electricity supply system;
- Regulation and policy risks.
Therefore, traditional techniques based on deterministic Discounted Cash Flow (DCF) for the investment appraisal are not fully adequate to evaluate these risks and uncertainties and the investor's flexibility to deal with them. Hence, the literature recommends to assess the value of risks and uncertainties through the Real Option Analysis (ROA), which is a valuable method in uncertain contexts.[116]
The economic valuation of large-scale applications (including pumped hydro storage and compressed air) considers benefits including: curtailment avoidance, grid congestion avoidance, price arbitrage and carbon-free energy delivery.[101][117][118] In one technical assessment by the Carnegie Mellon Electricity Industry Centre, economic goals could be met using batteries if their capital cost was $30 to $50 per kilowatt-hour.[101]
A metric of energy efficiency of storage is energy storage on energy invested (ESOI), which is the amount of energy that can be stored by a technology, divided by the amount of energy required to build that technology. The higher the ESOI, the better the storage technology is energetically. For lithium-ion batteries this is around 10, and for lead acid batteries it is about 2. Other forms of storage such as pumped hydroelectric storage generally have higher ESOI, such as 210.[119]
Pumped-storage hydroelectricity is by far the largest storage technology used globally.[120] However, the usage of conventional pumped-hydro storage is limited because it requires terrain with elevation differences and also has a very high land use for relatively small power.[121] In locations without suitable natural geography, underground pumped-hydro storage could also be used.[122] High costs and limited life still make batteries a "weak substitute" for dispatchable power sources, and are unable to cover for variable renewable power gaps lasting for days, weeks or months. In grid models with high VRE share, the excessive cost of storage tends to dominate the costs of the whole grid — for example, in California alone 80% share of VRE would require 9.6 TWh of storage but 100% would require 36.3 TWh. As of 2018 the state only had 150 GWh of storage, primarily in pumped storage and a small fraction in batteries. According to another study, supplying 80% of US demand from VRE would require a smart grid covering the whole country or battery storage capable to supply the whole system for 12 hours, both at cost estimated at $2.5 trillion.[123][124] Similarly, several studies have found that relying only on VRE and energy storage would cost about 30-50% more than a comparable system that combines VRE with nuclear plants or plants with carbon capture and storage instead of energy storage.[125][126]
Research
Germany
In 2013, the German Federal government allocated €200M (approximately US$270M) for research, and another €50M to subsidize battery storage in residential rooftop solar panels, according to a representative of the German Energy Storage Association.[127]
Siemens AG commissioned a production-research plant to open in 2015 at the Zentrum für Sonnenenergie und Wasserstoff (ZSW, the German Center for Solar Energy and Hydrogen Research in the State of Baden-Württemberg), a university/industry collaboration in Stuttgart, Ulm and Widderstall, staffed by approximately 350 scientists, researchers, engineers, and technicians. The plant develops new near-production manufacturing materials and processes (NPMM&P) using a computerized Supervisory Control and Data Acquisition (SCADA) system. It aims to enable the expansion of rechargeable battery production with increased quality and lower cost.[128][129]
United States
In 2014, research and test centers opened to evaluate energy storage technologies. Among them was the Advanced Systems Test Laboratory at the University of Wisconsin at Madison in Wisconsin State, which partnered with battery manufacturer Johnson Controls.[130] The laboratory was created as part of the university's newly opened Wisconsin Energy Institute. Their goals include the evaluation of state-of-the-art and next generation electric vehicle batteries, including their use as grid supplements.[130]
The State of New York unveiled its New York Battery and Energy Storage Technology (NY-BEST) Test and Commercialization Center at Eastman Business Park in Rochester, New York, at a cost of $23 million for its almost 1,700 m2 laboratory. The center includes the Center for Future Energy Systems, a collaboration between Cornell University of Ithaca, New York and the Rensselaer Polytechnic Institute in Troy, New York. NY-BEST tests, validates and independently certifies diverse forms of energy storage intended for commercial use.[131]
On September 27, 2017, Senators Al Franken of Minnesota and Martin Heinrich of New Mexico introduced Advancing Grid Storage Act (AGSA), which would devote more than $1 billion in research, technical assistance and grants to encourage energy storage in the United States.[132]
In grid models with high VRE share, the excessive cost of storage tends to dominate the costs of the whole grid — for example, in California alone 80% share of VRE would require 9.6 TWh of storage but 100% would require 36.3 TWh. According to another study, supplying 80% of US demand from VRE would require a smart grid covering the whole country or battery storage capable to supply the whole system for 12 hours, both at cost estimated at $2.5 trillion.[123][124]
United Kingdom
In the United Kingdom, some 14 industry and government agencies allied with seven British universities in May 2014 to create the SUPERGEN Energy Storage Hub in order to assist in the coordination of energy storage technology research and development.[133][134]
See also
References
Simple waterwheels were used in the Balkans of Europe in 100 B.C.E for powering flour mills. Elaborate Irrigation systems had been built In Egypt and Mesopotamia a thousand years before that, and it is very likely that these systems contained simple waterwheels. Waterwheels powered by a stream running underneath were common in the Roman Empire during the third and fourth centuries C.E. After the fall of the Western Roman Empire, water technology advanced further in the Middle East than in Europe, but waterwheels were commonly used to harness water as a source of power in Europe during the Middle Ages. The Doomsday Book of 1086 C.E. lists 5624 water powered mills in the southern half of England. The designs of more efficient waterwheels were brought back to Europe from the Middle East by the Crusaders and were used for grinding grain and for powering furnace bellows.
- New SUPERGEN Hub to set UK's energy storage course Archived May 8, 2014, at the Wayback Machine, ECNMag.com website, May 2, 2014.
Further reading
Journals and papers
- Chen, Haisheng; Thang Ngoc Cong; Wei Yang; Chunqing Tan; Yongliang Li; Yulong Ding. Progress in electrical energy storage system: A critical review, Progress in Natural Science, accepted July 2, 2008, published in Vol. 19, 2009, pp. 291–312, doi: 10.1016/j.pnsc.2008.07.014. Sourced from the National Natural Science Foundation of China and the Chinese Academy of Sciences. Published by Elsevier and Science in China Press. Synopsis: a review of electrical energy storage technologies for stationary applications. Retrieved from ac.els-cdn.com on May 13, 2014. (PDF)
- Corum, Lyn. The New Core Technology: Energy storage is part of the smart grid evolution, The Journal of Energy Efficiency and Reliability, December 31, 2009. Discusses: Anaheim Public Utilities Department, lithium ion energy storage, iCel Systems, Beacon Power, Electric Power Research Institute (EPRI), ICEL, Self Generation Incentive Program, ICE Energy, vanadium redox flow, lithium Ion, regenerative fuel cell, ZBB, VRB, lead acid, CAES, and Thermal Energy Storage. (PDF)
- de Oliveira e Silva, G.; Hendrick, P. (2016). "Lead-acid batteries coupled with photovoltaics for increased electricity self-sufficiency in households". Applied Energy. 178: 856–867. doi:10.1016/j.apenergy.2016.06.003.
- Whittingham, M. Stanley. History, Evolution, and Future Status of Energy Storage, Proceedings of the IEEE, manuscript accepted February 20, 2012, date of publication April 16, 2012; date of current version May 10, 2012, published in Proceedings of the IEEE, Vol. 100, May 13, 2012, 0018–9219, pp. 1518–1534, doi: 10.1109/JPROC.2012.219017. Retrieved from ieeexplore.ieee.org May 13, 2014. Synopsis: A discussion of the important aspects of energy storage including emerging battery technologies and the importance of storage systems in key application areas, including electronic devices, transportation, and the utility grid. (PDF)
Books
- GA Mansoori, N Enayati, LB Agyarko (2016), Energy: Sources, Utilization, Legislation, Sustainability, Illinois as Model State, World Sci. Pub. Co., ISBN 978-981-4704-00-7
- Díaz-González, Franscisco (2016). Energy storage in power systems. United Kingdom: John Wiley & Sons. ISBN 9781118971321.
External links
- U.S. Dept of Energy - Energy Storage Systems Government research center on energy storage technology.
- U.S. Dept of Energy - International Energy Storage Database Archived November 13, 2013, at the Wayback Machine The DOE International Energy Storage Database provides free, up-to-date information on grid-connected energy storage projects and relevant state and federal policies.
- IEEE Special Issue on Massive Energy Storage
- IEA-ECES - International Energy Agency - Energy Conservation through Energy Conservation programme.
- Energy Information Administration Glossary
- Energy Storage Project Regeneration.
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https://en.wikipedia.org/wiki/Energy_storage
In an electrical power distribution system, a ring main unit (RMU) is a factory assembled, metal enclosed set of switchgear used at the load connection points of a ring-type distribution network. It includes in one unit two switches that can connect the load to either or both main conductors, and a fusible switch or circuit breaker and switch that feed a distribution transformer. [1] The metal enclosed unit connects to the transformer either through a bus throat of standardized dimensions, or else through cables and is usually installed outdoors. Ring main cables enter and leave the cabinet. This type of switchgear is used for medium-voltage power distribution, from 7200 volts to about 36000 volts.
The ring main unit was introduced in the United Kingdom and is now widely used in other countries. In North American distribution practice, often the equivalent of a ring main unit is built into a pad-mounted transformer which integrates switches and transformer into a single cabinet.
Categories
Ring main units can be characterized by their type of insulation: air, oil or gas. The switch used to isolate the transformer can be a fusible switch, or may be a circuit breaker using vacuum or gas-insulated interrupters. The unit may also include protective relays to operate the circuit breaker on a fault.
See also
https://en.wikipedia.org/wiki/Ring_main_unit
https://en.wikipedia.org/wiki/Flywheel_energy_storage
https://en.wikipedia.org/wiki/Storage_heater
https://en.wikipedia.org/wiki/Molten_salt_heat_storage
https://en.wikipedia.org/wiki/Steam_accumulator
https://en.wikipedia.org/wiki/Power-to-gas
https://en.wikipedia.org/wiki/Reversible_solid_oxide_cell
Open-circuit voltage (abbreviated as OCV or VOC) is the difference of electrical potential between two terminals of an electronic device when disconnected from any circuit.[1] There is no external load connected. No external electric current flows between the terminals. Alternatively, the open-circuit voltage may be thought of as the voltage that must be applied to a solar cell or a battery to stop the current. It is sometimes given the symbol Voc. In network analysis this voltage is also known as the Thévenin voltage.
The open-circuit voltages of batteries and solar cells are often quoted under particular conditions (state-of-charge, illumination, temperature, etc.).
The potential difference mentioned for batteries and cells is usually the open-circuit voltage.
The value of the open-circuit voltage of a transducer equals its electromotive force (emf), which is the maximum potential difference it can produce when not providing current.
https://en.wikipedia.org/wiki/Open-circuit_voltage
https://en.wikipedia.org/wiki/Overpotential
https://en.wikipedia.org/wiki/Short_circuit
https://en.wikipedia.org/wiki/Electromotive_force
The reactions taking place on the oxygen electrode are the same considered for the hydrogen/steam case. Even if characterized by much slower kinetics with respect to the one involving hydrogen and steam, the direct electro-oxidation of carbon monoxide (forward reaction) or the direct electro-reduction of carbon dioxide (backward reaction) can be considered as well:
The thermoneutral voltage of the electrolysis is equal to 1.48 V.
One useful way to depict the cycling between SOFC and SOEC mode of the rSOC operation with carbonaceous reactants is the C-H-O ternary diagram.[6] Each point in the diagram represents a gas mixture with a different number of carbon, hydrogen or oxygen atoms. When dealing with the operation on reversible solid oxide cells, three distinct regions can be distinguished in the graph. For different operating conditions (i.e., different temperature and pressure), distinct boundary lines between these regions can be drawn. The three regions are:
- the carbon deposition region: gas mixtures lying in this region are characterized by compositions that are prone to carbon deposition on the fuel electrode;
- the fully oxidized region: this region is characterized by gas mixtures that are fully oxidized, hence they cannot be used as fuels in the rSOC;
- the operating region: this region is characterized by gas mixtures that are suitable for the rSOC operation.
In the operating region, the fuel mixture and the exhaust mixture can be depicted. These two points are connected by a line which runs through points characterized by a constant H/C ratio. In fact, during the rSOC operation in both modalities, the gases on the fuel electrode exchange with the oxygen electrode only oxygen atoms, while hydrogen and carbon are confined inside the fuel electrode. During the SOFC operation, the composition of the gas in the fuel electrode moves towards the boundary line of the fully oxidized region, increasing its oxygen content. During SOEC operation, on the other hand, the gas mixture evolves away from the fully oxidized region towards the carbon deposition region, while reducing its oxygen content.
https://en.wikipedia.org/wiki/Reversible_solid_oxide_cell
The gas may be used as chemical feedstock, or converted back into electricity using conventional generators such as gas turbines.[6] Power-to-gas allows energy from electricity to be stored and transported in the form of compressed gas, often using existing infrastructure for long-term transport and storage of natural gas. P2G is often considered the most promising technology for seasonal renewable energy storage.[7][8]
https://en.wikipedia.org/wiki/Power-to-gas
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
https://en.wikipedia.org/wiki/LNG_carrier
https://en.wikipedia.org/wiki/Pipeline_transport#Oil_and_natural_gas
https://en.wikipedia.org/wiki/Pipeline_transport#Oil_and_natural_gas
Construction and operation
Oil pipelines are made from steel or plastic tubes with inner diameter typically from 4 to 48 inches (100 to 1,220 mm). Most pipelines are typically buried at a depth of about 3 to 6 feet (0.91 to 1.83 m). To protect pipes from impact, abrasion, and corrosion, a variety of methods are used. These can include wood lagging (wood slats), concrete coating, rockshield, high-density polyethylene, imported sand padding, sacrificial cathodes and padding machines.[13]
Crude oil contains varying amounts of paraffin wax and in colder climates wax buildup may occur within a pipeline. Often these pipelines are inspected and cleaned using pigging, the practice of using devices known as "pigs" to perform various maintenance operations on a pipeline. The devices are also known as "scrapers" or "Go-devils". "Smart pigs" (also known as "intelligent" or "intelligence" pigs) are used to detect anomalies in the pipe such as dents, metal loss caused by corrosion, cracking or other mechanical damage.[14] These devices are launched from pig-launcher stations and travel through the pipeline to be received at any other station down-stream, either cleaning wax deposits and material that may have accumulated inside the line or inspecting and recording the condition of the line.
For natural gas, pipelines are constructed of carbon steel and vary in size from 2 to 60 inches (51 to 1,524 mm) in diameter, depending on the type of pipeline. The gas is pressurized by compressor stations and is odorless unless mixed with a mercaptan odorant where required by a regulating authority.
Ammonia
A major ammonia pipeline is the Ukrainian Transammiak line connecting the TogliattiAzot facility in Russia to the exporting Black Sea-port of Odesa.
Alcohol fuels
Pipelines have been used for transportation of ethanol in Brazil, and there are several ethanol pipeline projects in Brazil and the United States.[15] The main problems related to the transport of ethanol by pipeline are its corrosive nature and tendency to absorb water and impurities in pipelines, which are not problems with oil and natural gas.[15][16] Insufficient volumes and cost-effectiveness are other considerations limiting construction of ethanol pipelines.[16][17] In the US minimal amounts of ethanol are transported by pipeline. Most ethanol is shipped by rail, the main alternatives being truck and barge. Delivering ethanol by pipeline is the most desirable option, but ethanol's affinity for water and solvent properties require the use of a dedicated pipeline, or significant cleanup of existing pipelines.
Coal and ore
Slurry pipelines are sometimes used to transport coal or ore from mines. The material to be transported is closely mixed with water before being introduced to the pipeline; at the far end, the material must be dried. One example is a 525-kilometre (326 mi) slurry pipeline which is planned to transport iron ore from the Minas-Rio mine (producing 26.5 million tonnes per year) to the Port of Açu in Brazil.[18] An existing example is the 85-kilometre (53 mi) Savage River Slurry pipeline in Tasmania, Australia, possibly the world's first when it was built in 1967. It includes a 366-metre (1,201 ft) bridge span at 167 metres (548 ft) above the Savage River.[19][20]
Hydrogen
Hydrogen pipeline transport is a transportation of hydrogen through a pipe as part of the hydrogen infrastructure. Hydrogen pipeline transport is used to connect the point of hydrogen production or delivery of hydrogen with the point of demand, with transport costs similar to CNG,[21] the technology is proven.[22] Most hydrogen is produced at the place of demand with every 50 to 100 miles (160 km) an industrial production facility.[23] The 1938 Rhine-Ruhr 240-kilometre (150 mi) hydrogen pipeline is still in operation.[24] As of 2004, there are 900 miles (1,400 km) of low pressure hydrogen pipelines in the US and 930 miles (1,500 km) in Europe.
Water
Two millennia ago, the ancient Romans made use of large aqueducts to transport water from higher elevations by building the aqueducts in graduated segments that allowed gravity to push the water along until it reached its destination. Hundreds of these were built throughout Europe and elsewhere, and along with flour mills were considered the lifeline of the Roman Empire. The ancient Chinese also made use of channels and pipe systems for public works. The famous Han Dynasty court eunuch Zhang Rang (d. 189 AD) once ordered the engineer Bi Lan to construct a series of square-pallet chain pumps outside the capital city of Luoyang.[25] These chain pumps serviced the imperial palaces and living quarters of the capital city as the water lifted by the chain pumps was brought in by a stoneware pipe system.[25][26]
Pipelines are useful for transporting water for drinking or irrigation over long distances when it needs to move over hills, or where canals or channels are poor choices due to considerations of evaporation, pollution, or environmental impact.
The 530 km (330 mi) Goldfields Water Supply Scheme in Western Australia using 750 mm (30 inch) pipe and completed in 1903 was the largest water supply scheme of its time.[27][28]
Examples of significant water pipelines in South Australia are the Morgan-Whyalla pipeline (completed 1944) and Mannum-Adelaide pipeline (completed 1955) pipelines, both part of the larger Snowy Mountains scheme.[29]
There are two Los Angeles, California aqueducts, the Owens Valley aqueduct (completed 1913) and the Second Los Angeles Aqueduct (completed 1970) which also include extensive use of pipelines.
The Great Manmade River of Libya supplies 3,680,000 cubic metres (4,810,000 cu yd) of water each day to Tripoli, Benghazi, Sirte, and several other cities in Libya. The pipeline is over 2,800 kilometres (1,700 mi) long, and is connected to wells tapping an aquifer over 500 metres (1,600 ft) underground.[30]
Other systems
District heating
District heating or teleheating systems consist of a network of insulated feed and return pipes which transport heated water, pressurized hot water, or sometimes steam to the customer. While steam is hottest and may be used in industrial processes due to its higher temperature, it is less efficient to produce and transport due to greater heat losses. Heat transfer oils are generally not used for economic and ecological reasons. The typical annual loss of thermal energy through distribution is around 10%, as seen in Norway's district heating network.[32]
District heating pipelines are normally installed underground, with some exceptions. Within the system, heat storage may be installed to even out peak load demands. Heat is transferred into the central heating of the dwellings through heat exchangers at heat substations, without mixing of the fluids in either system.
Beer
Bars in the Veltins-Arena, a major football ground in Gelsenkirchen, Germany, are interconnected by a 5-kilometre (3.1 mi) long beer pipeline. In Randers city in Denmark, the so-called Thor Beer pipeline was operated. Originally, copper pipes ran directly from the brewery, but when the brewery moved out of the city in the 1990s, Thor Beer replaced it with a giant tank.
A three-kilometer beer pipeline was completed in Bruges, Belgium in September 2016 to reduce truck traffic on the city streets.[33]
Brine
The village of Hallstatt in Austria, which is known for its long history of salt mining, claims to contain "the oldest industrial pipeline in the world", dating back to 1595.[34] It was constructed from 13,000 hollowed-out tree trunks to transport brine 40 kilometres (25 mi) from Hallstatt to Ebensee.[35]
https://en.wikipedia.org/wiki/Pipeline_transport#Oil_and_natural_gas
Marine pipelines
In places, a pipeline may have to cross water expanses, such as small seas, straits and rivers.[37] In many instances, they lie entirely on the seabed. These pipelines are referred to as "marine" pipelines (also, "submarine" or "offshore" pipelines). They are used primarily to carry oil or gas, but transportation of water is also important.[37] In offshore projects, a distinction is made between a "flowline" and a pipeline.[37][38][39] The former is an intrafield pipeline, in the sense that it is used to connect subsea wellheads, manifolds and the platform within a particular development field. The latter, sometimes referred to as an "export pipeline", is used to bring the resource to shore.[38] The construction and maintenance of marine pipelines imply logistical challenges that are different from those onland, mainly because of wave and current dynamics, along with other geohazards. In Nigeria oil pipelines get bored by thieves, in 2022, during the Russian-Ukrainian war, the submarine natural gas pipelines Nord Stream I and II got blasted.
Functions
In general, pipelines can be classified in three categories depending on purpose:
- Gathering pipelines
- Group of smaller interconnected pipelines forming complex networks with the purpose of bringing crude oil or natural gas from several nearby wells to a treatment plant or processing facility. In this group, pipelines are usually short- a couple hundred metres- and with small diameters. Sub-sea pipelines for collecting product from deep water production platforms are also considered gathering systems.
- Transportation pipelines
- Mainly long pipes with large diameters, moving products (oil, gas, refined products) between cities, countries and even continents. These transportation networks include several compressor stations in gas lines or pump stations for crude and multi-products pipelines.
- Distribution pipelines
- Composed of several interconnected pipelines with small diameters, used to take the products to the final consumer. Feeder lines to distribute gas to homes and businesses downstream. Pipelines at terminals for distributing products to tanks and storage facilities are included in this groups.
https://en.wikipedia.org/wiki/Pipeline_transport#Oil_and_natural_gas
Operation
Field devices are instrumentation, data gathering units and communication systems. The field instrumentation includes flow, pressure, and temperature gauges/transmitters, and other devices to measure the relevant data required. These instruments are installed along the pipeline on some specific locations, such as injection or delivery stations, pump stations (liquid pipelines) or compressor stations (gas pipelines), and block valve stations.
The information measured by these field instruments is then gathered in local remote terminal units (RTU) that transfer the field data to a central location in real time using communication systems, such as satellite channels, microwave links, or cellular phone connections.
Pipelines are controlled and operated remotely, from what is usually known as the "Main Control Room". In this center, all the data related to field measurement is consolidated in one central database. The data is received from multiple RTUs along the pipeline. It is common to find RTUs installed at every station along the pipeline.
The SCADA system at the Main Control Room receives all the field data and presents it to the pipeline operator through a set of screens or Human Machine Interface, showing the operational conditions of the pipeline. The operator can monitor the hydraulic conditions of the line, as well as send operational commands (open/close valves, turn on/off compressors or pumps, change setpoints, etc.) through the SCADA system to the field.
To optimize and secure the operation of these assets, some pipeline companies are using what is called "Advanced Pipeline Applications", which are software tools installed on top of the SCADA system, that provide extended functionality to perform leak detection, leak location, batch tracking (liquid lines), pig tracking, composition tracking, predictive modeling, look ahead modeling, and operator training.
https://en.wikipedia.org/wiki/Pipeline_transport#Oil_and_natural_gas
Supervisory control and data acquisition (SCADA) is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and other devices, such as programmable logic controllers, which interface with process plant or machinery.
https://en.wikipedia.org/wiki/SCADA#Human_Machine_Interface
A geologic hazard or geohazard is an adverse geologic condition capable of causing widespread damage or loss of property and life.[1] These hazards are geological and environmental conditions and involve long-term or short-term geological processes. Geohazards can be relatively small features, but they can also attain huge dimensions (e.g., submarine or surface landslide) and affect local and regional socio-economics to a large extent (e.g., tsunamis).
Sometimes the hazard is instigated by the careless location of developments or construction in which the conditions were not taken into account. Human activities, such as drilling through overpressured zones, could result in significant risk, and as such mitigation and prevention are paramount, through improved understanding of geohazards, their preconditions, causes and implications. In other cases, particularly in montane regions, natural processes can cause catalytic events of a complex nature, such as an avalanche hitting a lake and causing a debris flow, with consequences potentially hundreds of miles away, or creating a lahar by volcanism.
Marine geohazards in particular constitute a fast-growing sector of research as they involve seismic, tectonic, volcanic processes now occurring at higher frequency, and often resulting in coastal sub-marine avalanches or devastating tsunamis in some of the most densely populated areas of the world [2] [3]
Such impacts on vulnerable coastal populations, coastal infrastructures, offshore exploration platforms, obviously call for a higher level of preparedness and mitigation. [4][5]
Speed of development
Sudden phenomena
Sudden phenomena include:
- avalanches (snow or rock) and its runout
- earthquakes and earthquake-triggered phenomena such as tsunamis
- forest fires (espec. in Mediterranean areas) leading to deforestation
- geomagnetic storms[6]
- gulls (chasms) associated with cambering of valley sides
- ice jams (Eisstoß) on rivers or glacial lake outburst floods below a glacier
- landslide (displacement of earth materials on a slope or hillside)
- mudflows (avalanche-like muddy flow of soft/wet soil and sediment materials, narrow landslides)
- pyroclastic flows
- rockfalls, rock slides, (rock avalanche) and debris flows
- torrents (flash floods, rapid floods or heavy current creeks with irregular course)
- liquefaction (settlement of the ground in areas underlain by loose saturated sand/silt during an earthquake event)
- volcanic eruptions, lahars and ash falls.
Slow phenomena
Gradual or slow phenomena include:
- alluvial fans (e.g. at the exit of canyons or side valleys)
- caldera development (volcanoes)
- geyser deposits
- ground settlement due to consolidation of compressible soils or due to collapseable soils (see also compaction)
- ground subsidence, sags and sinkholes
- sand dune migration
- shoreline and stream erosion
- thermal springs
Evaluation and mitigation
Geologic hazards are typically evaluated by engineering geologists who are educated and trained in interpretation of landforms and earth process, earth-structure interaction, and in geologic hazard mitigation. The engineering geologist provides recommendations and designs to mitigate for geologic hazards. Trained hazard mitigation planners also assist local communities to identify strategies for mitigating the effects of such hazards and developing plans to implement these measures. Mitigation can include a variety of measures:
- Geologic hazards may be avoided by relocation. Publicly available databases, via searchable platforms,[7] can help people evaluate hazards in locations of interest.
- The stability of sloping earth can be improved by the construction of retaining walls, which may use techniques such as slurry walls, shear pins, tiebacks, soil nails or soil anchors. Larger projects may use gabions and other forms of earth buttress.
- Shorelines and streams are protected against scour and erosion using revetments and riprap.
- The soil or rock itself may be improved by means such as dynamic compaction, injection of grout or concrete, and mechanically stabilized earth.
- Additional mitigation methods include deep foundations, tunnels, surface and subdrain systems, and other measures.
- Planning measures include regulations prohibiting development near hazard-prone areas and adoption of building codes.
In paleohistory
Eleven distinct flood basalt episodes occurred in the past 250 million years, resulting in large volcanic provinces, creating lava plateaus and mountain ranges on Earth.[8] Large igneous provinces have been connected to five mass extinction events. The timing of six out of eleven known provinces coincide with periods of global warming and marine anoxia/dysoxia. Thus, suggesting that volcanic CO2 emissions can force an important effect on the climate system.[9]
Known hazards
- 2004 Indian Ocean earthquake and tsunami
- 2008 Sichuan earthquake
- 2011 Tōhoku earthquake and tsunami
- The Barrier (located in Garibaldi Provincial Park)
- Usoi Dam a natural landslide dam
Eisstoß Feb.2006 Vienna, Austria (Donauinsel)
Glacier just above Grindelwald, Switzerland
Soil liquefaction during the 1964 Niigata earthquake
See also
References
- P.B. Wignall (2001). "Large igneous provinces and mass extinctions". Earth-Science Reviews. 53 (1–2): 1–33. Bibcode:2001ESRv...53....1W. doi:10.1016/S0012-8252(00)00037-4.
External links
Media related to Geological hazards at Wikimedia Commons- International Centre for Geohazards (ICG)
https://en.wikipedia.org/wiki/Geological_hazard
A wellhead is the component at the surface of an oil or gas well that provides the structural and pressure-containing interface for the drilling and production equipment.
The primary purpose of a wellhead is to provide the suspension point and pressure seals for the casing strings that run from the bottom of the hole sections to the surface pressure control equipment.[1]
While drilling the oil well, surface pressure control is provided by a blowout preventer (BOP). If the pressure is not contained during drilling operations by the column of drilling fluid, casings, wellhead, and BOP, a well blowout could occur.
When the well has been drilled, it is completed to provide an interface with the reservoir rock and a tubular conduit for the well fluids. The surface pressure control is provided by a Christmas tree, which is installed on top of the wellhead, with isolation valves and choke equipment to control the flow of well fluids during production.
Wellheads are typically welded onto the first string of casing, which has been cemented in place during drilling operations, to form an integral structure of the well. In exploration wells that are later abandoned, the wellhead may be recovered for refurbishment and re-use.
Offshore, where a wellhead is located on the production platform it is called a surface wellhead, and if located beneath the water then it is referred to as a subsea wellhead or mudline wellhead.[2][3][4][5]
Components
The primary components of a wellhead system are:
- casing head
- casing spools
- casing hangers
- choke manifold
- packoffs (isolation) seals
- test plugs
- mudline suspension systems
- tubing heads
- tubing hangers
- tubing head adapter
Functions
A wellhead serves numerous functions, some of which are:
- Provide a means of casing suspension. (Casing is the permanently installed pipe used to line the well hole for pressure containment and collapse prevention during the drilling phase).
- Provides a means of tubing suspension. (Tubing is removable pipe installed in the well through which well fluids pass).
- Provides a means of pressure sealing and isolation between casing at surface when many casing strings are used.
- Provides pressure monitoring and pumping access to annuli between the different casing/tubing strings.
- Provides a means of attaching a blowout preventer during drilling.
- Provides a means of attaching a Christmas tree for production operations.
- Provides a reliable means of well access.
- Provides a means of attaching a well pump,
Design specification
The oil industry specifications for wellhead systems (materials, dimensions, test procedures and pressure ratings etc.) are :
- API 6A, 20th Edition, October 2010; Specification for Wellhead and Christmas Tree Equipment
- ISO 10423:2009 Wellhead and Christmas Tree Equipment
In general well heads are five nominal ratings of wellheads: 2, 3, 5, 10 and 15 (x1000) psi working pressure. They have an operating temperature range of -50 to +250 degrees Fahrenheit. They are used in conjunction with ring type seal gaskets.
In general the yield strength of the materials range from 36000 to 75000 psi.
See also
- Puteal — Water well head
- Pumpjack
- American Petroleum Institute
- Drilling rig (petroleum)
References
External links
https://en.wikipedia.org/wiki/Wellhead
A puteal (Latin: from puteus (well) — plural: putealia[1]) is a classical wellhead built around a water well's access opening.
Description
The enclosure keeps people from falling down a well otherwise open at grade level.[2] When equipped with a cast iron lid, as traditionally in the public squares, or campos, of Venice, Italy, the citizens and water supply were protected.[1]
Putealia were used as an accessible point of water distribution, and as an aesthetic architectural element. Locations included public town squares and private courtyards.[1] They were often found in atriums, where they gave access to the water cistern fed by the impluvium.
Classical putealia
The classical puteal is made of carved stone, often marble in Europe. They are frequently decorated with bas-reliefs of classical Greek and Roman themes around their outer faces. An Ancient Roman one was in the Puteal Scribonianum structure in the Roman Forum, nothing remains.
The term is also used for circular classical remains (spolia) recycled after antiquity into wellheads, such as the Guildford Puteal at the British Museum.
See also
- Bidental
- Fontus (Fons) — the ancient Roman god of fountains and wellheads
- Wishing well
References
- John Weale, Rudimentary Dictionary of Terms Used in Architecture, Civil, Architecture, Naval, Building and Construction, Early and Ecclesiastical Art, Engineering, Civil, Engineering, Mechanical, Fine Art, Mining, Sur-veying, Etc., to Which Are Added Explanatory Observations on Numerous Subjects Connected with Practical Art and Science. (London: J. Weale, 1849), pg. 364.
 | This Ancient Rome–related article is a stub. You can help Wikipedia by expanding it. |
https://en.wikipedia.org/wiki/Puteal
A pumpjack is the overground drive for a reciprocating piston pump in an oil well.[1]
https://en.wikipedia.org/wiki/Pumpjack
A beam engine is a type of steam engine where a pivoted overhead beam is used to apply the force from a vertical piston to a vertical connecting rod. This configuration, with the engine directly driving a pump, was first used by Thomas Newcomen around 1705 to remove water from mines in Cornwall. The efficiency of the engines was improved by engineers including James Watt, who added a separate condenser; Jonathan Hornblower and Arthur Woolf, who compounded the cylinders; and William McNaught, who devised a method of compounding an existing engine. Beam engines were first used to pump water out of mines or into canals but could be used to pump water to supplement the flow for a waterwheel powering a mill.
The rotative beam engine is a later design of beam engine where the connecting rod drives a flywheel by means of a crank (or, historically, by means of a sun and planet gear). These beam engines could be used to directly power the line-shafting in a mill. They also could be used to power steam ships.
History
The first beam engines were water-powered and used to pump water from mines. A preserved example may be seen at the Straitsteps Lead Mine in Wanlockhead in Scotland.
Beam engines were extensively used to power pumps on the English canal system when it was expanded by means of locks early in the Industrial Revolution, and also to drain water from mines in the same period, and as winding engines.
The first steam-related beam engine was developed by Thomas Newcomen. This was not, strictly speaking, steam powered, as the steam introduced below the piston was condensed to create a partial vacuum thus allowing atmospheric pressure to push down the piston. It was therefore called an Atmospheric Engine. The Newcomen atmospheric engine was adopted by many mines in Cornwall and elsewhere, but it was relatively inefficient and consumed a large quantity of fuel. The engine was improved by John Smeaton but James Watt resolved the main inefficiencies of the Newcomen engine in his Watt steam engine by the addition of a separate condenser, thus allowing the cylinder to remain hot. Technically this was still an atmospheric engine until (under subsequent patents) he enclosed the upper part of the cylinder, introducing steam to also push the piston down. This made it a true steam engine and arguably confirms him as the inventor of the steam engine. He also patented the centrifugal governor and the parallel motion. the latter allowed the replacement of chains round an arch head and thus allowed its use as a rotative engine.
His patents remained in place until the start of the 19th Century and some say that this held back development. However, in reality development had been ongoing by others and at the end of the patent period there was an explosion of new ideas and improvements. Watt's beam engines were used commercially in much larger numbers and many continued to run for 100 years or more.
Watt held patents on key aspects of his engine's design, but his rotative engine was equally restricted by James Pickard's patent of the simple crank. The beam engine went on to be considerably improved and enlarged in the tin- and copper-rich areas of south west England, which enabled the draining of the deep mines that existed there. Consequently, the Cornish beam engines became world-famous, as they remain among the most massive beam engines ever constructed.
Because of the number of patents on various parts of the engines and the consequences of patent infringements, examples exist of Beam Engines with no makers name on any of the parts (Hollycombe Steam Collection).
Rotative beam engines
In a rotative beam engine, the piston is mounted vertically, and the piston rod drives the beam as before. A connecting rod from the other end of the beam, rather than driving a pump rod, now drives a flywheel.
Early Watt engines used Watt's patent sun and planet gear, rather than a simple crank, as use of the latter was protected by a patent owned by James Pickard. Once the patent had expired, the simple crank was employed universally. Once rotary motion had been achieved a drive belt could be attached beside the flywheel. This transmitted the power to other drive shafts and from these other belts could then be attached to power a variety of static machinery e.g. threshing, grinding or milling machines.
Marine beam engines
The first steam-powered ships used variants of the rotative beam engine. These marine steam engines – known as side-lever, grasshopper, crosshead, or 'walking beam', among others – all varied from the original land-based machines by locating the beam or beams in different positions to take up less room on board ship.
Compounding
Compounding involves two or more cylinders; low-pressure steam from the first, high-pressure, cylinder is passed to the second cylinder where it expands further and provides more drive. This is the compound effect; the waste steam from this can produce further work if it is then passed into a condenser in the normal way. The first experiment with compounding was conducted by Jonathan Hornblower, who took out a patent in 1781. His first engine was installed at Tincroft Mine, Cornwall. It had two cylinders – one 21-inch (0.53 m) diameter with 6-foot (1.8 m) stroke and one 27-inch (0.69 m) diameter with 8-foot (2.4 m) stroke – placed alongside each other at one end of the beam. The early engines showed little performance gain: the steam pressure was too low, interconnecting pipes were of small diameter and the condenser ineffective.[1]
At this time the laws of thermodynamics were not adequately understood, particularly the concept of absolute zero. Engineers such as Arthur Woolf were trying to tackle an engineering problem with an imperfect understanding of the physics. In particular, their valve gear was cutting-in at the wrong position in the stroke, not allowing for expansive working in the cylinder. Successful Woolf compound engines were produced in 1814, for the Wheal Abraham copper mine and the Wheal Vor tin mine.[2]
McNaught engines
William McNaught patented a compound beam engine in 1845. On a beam engine of the standard Boulton & Watt design he placed a high-pressure cylinder, on the opposite side of the beam to the existing single cylinder, where the water pump was normally fitted. This had two important effects: it massively reduced the pressure on the beam, and the connecting steam pipe, being long, acted as an expansive receiver – the element missing in the Woolf design.[3] This modification could be made retrospectively, and engines so modified were said to be "McNaughted". The advantages of a compound engine were not significant at pressures under 60 pounds per square inch (410 kPa), but showed at over 100 psi (690 kPa).[citation needed]
Preserved beam engines
- Abbey Pumping Station (Leicester, England) - houses four Woolf compound rotative beam engines built by Gimson and Company, Leicester.[4]
- Bolton Steam Museum (Bolton, England) – includes several rotative beam engines originally used to drive mills
- Claymills Pumping Station (Burton upon Trent, England) - four Woolf compound, rotative, beam pumping engines; five Lancashire boilers; over thirty auxiliary engines on the site, including the oldest working steam driven dynamo in the country.
- Coldharbour Mill (Uffculme, Devon) - 1867 Kittoe and Brotherhood beam engine plus Pollit & Wigzell 300 hp cross compound engine. In steam most Bank Holidays driving the rope race, together with other smaller machines.
- Coultershaw Beam Pump (West Sussex, England) – preserved water-powered beam engine from 1782.
- Crofton Pumping Station (Great Bedwyn, England) – two engines, including the oldest working 'Cornish' engine, in its original location, in the world (1812).
- Crossness Pumping Station (Abbey Wood, England) – set of four rotative beam engines: the largest surviving working examples.
- Dogdyke Engine (Tattershall, England) – drainage engine and scoop wheel, steamed summer weekends.
- Eastney Beam Engine House (Portsmouth, England) – contains two rotative beam engines for sewage-pumping, dating from 1887.
- Elsecar Heritage Centre (Elsecar, England) – the only surviving Newcomen engine (in the world) to have remained in its original location (1795).
- Goulburn Waterworks (Goulburn, Australia) - Appleby Bros Beam Engine (1883) 120 hp in working order still in the original pump house building.
- Grazebrook beam engine- A large pumping Boulton & Watt designed with a 42-inch (1.1 m) bore on static display on the Dartmouth roundabout on the A38(M) in Birmingham, England.
- Hollycombe Steam Collection (Liphook, England) - A small (approx 5 horse power) working rotative bean engine dating from approx 1850, used to power farm machinery, with a water wheel attached to supplement the power.
- Levant Mine and Beam Engine (Trewellard, England) – a working beam engine on a National Trust property in West Cornwall, England
- Markfield Beam Engine (Tottenham, England) – a compound, rotative engine.
- Museum De Cruquius (Cruquius, The Netherlands) – the eight-beamed engine at Cruquius is thought to be the largest steam engine ever built
- Newcomen Memorial Engine (Dartmouth, England) - dating from about 1725. Hydraulic mechanism added for demonstration purposes.
- Nottingham Industrial Museum (Nottingham, England) - The Steam Gallery contains an impressive Basford Beam Engine, one of a pair of engines built in 1858 by R&W Hawthorn in Newcastle upon Tyne. It was installed at Basford Pumping Station to lift water 110 ft (34 m) from the sandstone below to supply fresh water to the City of Nottingham. The engine was replaced in 1965 and was removed to the purpose-built Steam Gallery where it was first fired in 1975.
- Pinchbeck Engine (Spalding, England) – statically preserved 'A'-frame engine.
- Poldark Mine (Trenear, England) - Harvey's of Hayle Cornish Beam Engine from Bunny Tin Mine and later Greensplat China Clay Pit dating from about 1850. Hydraulic mechanism added for demonstration purposes. Last to have worked commercially in Cornwall to December 1959, moved to Poldark in 1972.[5]
- Ryhope Engines Museum (Ryhope, England) – twin rotative beam engines; built 1868.
- Smethwick Engine (Smethwick, England) – oldest working steam engine in the world (1779).
- Stretham Old Engine (Stretham, England) – Statically preserved engine and scoop wheel.
- Strumpshaw Steam Museum (Strumpshaw, England) - Features a now Compressed Air powered former beam engine from Addington.
- Tees Cottage Pumping Station (Darlington, England) - a working rotative, two-cylinder Woolf compound engine, designed by Glenfield and Kennedy of Kilmarnock and built by Teasdale Bros, under T&C Hawksley, Civil Engineers, London.
- The Boulton and Watt rotative beam engine (sun and planet type) at the National Museum of Scotland (1786).[6][7] Occasional working by pneumatics
- The Caprington Colliery Newcomen engine at the National Museum of Scotland. Occasional working on pneumatics.
- The Henry Ford Museum (Dearborn, Michigan, US) - Fairbottom Bobs, a Newcomen engine of the 1760s.
- London Museum of Water & Steam (Brentford, England) – five 'Cornish' engines (in original location) of which four are operational, together with two operational rotative beam engines (in museum), including the largest working 'Cornish' engine in the world with a 90-inch (2,286 mm) Cylinder.
- Western Springs Water Works (Auckland, New Zealand) – 1877 double Woolf compound engine. In original location, restored in working order with Transport and Technology Museum built around it. The restoration of the Pumphouse and original Engineers cottage was awarded with the 2009 Award of Merit from UNESCO's Asia-Pacific Heritage Awards for Culture Heritage Conservation programme.
See also
References
Bibliography
Further reading
- Crowley, T.E. (1982). The Beam Engine. Senecio Publishing. ISBN 0-906831-02-4.
External links
- Animation of a Watt beam engine.
- The oldest surviving mine engine in Cornwall.
- Archive footage of the engines at Addington Pumping Station in July 1973, a year prior to decommissioning.
- Working model beam engine
https://en.wikipedia.org/wiki/Beam_engine
A blowing engine is a large stationary steam engine or internal combustion engine directly coupled to air pumping cylinders. They deliver a very large quantity of air at a pressure lower than an air compressor, but greater than a centrifugal fan.
Blowing engines are majorly used to provide the air blast for furnaces, blast furnaces and other forms of smelter.
Waterwheel engines
The very first blowing engines were the blowing houses: bellows, driven by waterwheels.
Smelters are most economically located near the source of their ore, which may not have suitable water power available nearby. There is also the risk of drought interrupting the water supply, or of expanding demand for the furnace outstripping the available water capacity.
These restrictions led to the very earliest form of steam engine used for power generation rather than pumping, the water-returning engine. With this engine, a steam pump was used to raise water that in turn drove a waterwheel and thus the machinery. Water from the wheel was then returned by the pump. These early steam engines were only suitable for pumping water, and could not be connected directly to the machinery.
The first practical examples of these engines were installed in 1742 at Coalbrookdale[1] and as improvements to the Carron Ironworks on the Clyde in 1765.[2]
Beam blowing engines
Early steam prime movers were beam engines, firstly of the non-rotative (i.e. solely reciprocating) and later the rotative type (i.e. driving a flywheel). Both of these were used as blowing engines, usually by coupling an air cylinder to the far end of the beam from the steam cylinder. Joshua Field describes an 1821 trip to Foster, Rastrick & Co. of Stourbridge,[3] where he observed eight large beam engines, one of 30 hp working a blowing cylinder of 5 feet diameter and 6 feet stroke.
Where the later beam engines drove flywheels, this was useful for providing a more even action to the engine. The air cylinder was still driven by the beam alone and the flywheel was used solely as a flywheel, not driving an output shaft. A well-known surviving example of this type are the paired beam engines "David & Sampson", now preserved at Blists Hill open-air museum, Ironbridge Gorge.[4][5] These are a pair of single-cylinder condensing beam engines, each driving an air cylinder by their own beam, but sharing a single flywheel between them. They are notable for their decorative Doric arches.[6] The engines had a long working life: 50 years of primary service from 1851 providing the blast for the Priors Lee furnaces of the Lilleshall Company,[7][8] then a further 50 years until the plant's closure as reserve engines, still being worked occasionally.[9]
Semi-rotative blowing engines
The large vertical blowing engine illustrated at the top was built in the 1890s by E. P. Allis Co. of Milwaukee (later to form part of Allis-Chalmers). The steam cylinder (lower) is 42 inches (1.1 m) diameter, the air cylinder (upper) 84 inches (2.1 m) and both with a stroke of 60 inches (1.5 m).
The steam cylinder has Reynolds-Corliss valve gear, driven via a bevel-driven auxiliary shaft beneath, at right-angles to the crankshaft.[10] This also means that the Corliss' wrist plate is at right-angles to the flywheel, rather than parallel as is usual. Edwin Reynolds was the designer of the Allis company and in 1876 had developed an improved version of the Corliss valvegear, with improved trip gear capable of working at higher speeds.[11] The air valves are also driven by eccentrics from this same shaft.
Like the beam engines, the main force of the piston is transmitted to the air cylinder by a purely reciprocating action and the flywheels exist to smooth the action of the engine. To permit adjustment, the steam piston rod only goes as far as the crosshead. Above this are twinned rods to the air piston. The flywheel shaft is mounted below the steam piston, the paired connecting rods driving downwards and backwards to make this a return connecting rod engine.
Internal combustion blowing engines
In the late 1800s, internal combustion gas engines were developed to burn gasses produced from blast furnaces, eliminating the need for fuel for steam boilers and increasing efficiency. Bethlehem Steel was one such company to employ this technology.[12] Huge, usually single-cylinder horizontal engines burned blast furnace gas. SA John Cockerill of Belgium and Körting of Hannover were both noted makers of such engines.
There are some efforts underway to restore a few of these engines.[13] A few firms still manufacture and install multi cylinder internal combustion engines to burn waste gasses today.[14]
Replacement by rotary blowers
As blast furnaces re-equipped after World War II, the favoured power source was either the diesel engine or the electric motor. These both had a rotary output, which worked well with contemporary developments in centrifugal fans capable of handling the huge volumes of air. Although the reciprocating steam blowing engine continued where it was already in use, they were rarely installed after the war. These older plants began to close in the 1950s and numbers were drastically reduced throughout the West during the 1970s. Blowing engines of this form are now rare.
Surviving examples today
Examples of both a beam blowing engine[4][5] and a vertical engine[5] may be seen at the Blists Hill open-air museum, Ironbridge Gorge. The beam engines "David & Sampson" are scheduled monuments.[4]
An 1817 beam blowing engine by Boulton & Watt, formerly used at the Netherton ironworks of M W Grazebrook, now decorates Dartmouth Circus, a traffic island at the start of the A38(M) motorway in Birmingham (see picture above, location: 52.492537°N 1.888189°W).
References
Blowing engines.
The third engine is very handsome a 6 column engine [a beam engine with a horizontal frame raised on columns] of 30 H Power working a blowing cylinder of 5 feet, 6 feet stroke"
https://en.wikipedia.org/wiki/Blowing_engine
Musgrave's non-dead-centre engine was a stationary steam engine of unusual design, intended to solve the problem of stopping on dead centre. It was designed in 1887 to serve as a marine engine. It used a pair of linked cylinders to prevent the engine from stopping in a position where no turning force can be applied. At least one engine is known to survive.
Dead centres
The 'dead centre' of a piston engine with cranks is when the piston is at the exact top or bottom of the stroke and so the piston cannot exert any torque on the crankshaft. If a steam engine stops on dead centre, it will be unable to restart from that position.
Several solutions to this have been applied. One of the simplest is to try not to stop in this position, the crudest to apply a strong arm with a crowbar to turn the engine over a little. Small steam barring engines were also used to move the engine away from dead centre before starting. If the engine has multiple cylinders, most geometries for these are arranged so that all cylinders are never at dead centre together and so one may always be used for starting.
Musgrave's solution was more complex: using two cylinders, additional connecting rod linkages, and geometry to avoid the problem.
Dead centre is rarely a problem for internal combustion engines, as these usually require cranking over to provide cylinder compression and so do not attempt to self-start from stationary. Some large stationary diesel engines, where these used a compressed air starting mechanism, have suffered from the problem of dead centres and so used a small manual barring gear.
Geometry
In appearance, the engine resembles a 'parallel twin' with two vertical cylinders and a single crankshaft between them, but set perpendicular to the line of the cylinders and sharing a single crankpin.
A parallel twin with this many cylinders would be self-starting from dead centre anyway (assuming the usual crankshaft with cranks at 90°).
The geometry in operation is more like that of a vee-twin engine. The two cylinders work together, but with one leading the other by approx. 30°. The difference in this case is that the cylinders are no longer directly in line with the crankshaft and so use the connecting rod as a form of bellcrank. If one cylinder is at dead centre, the other will be away from it by the amount of this angle.
A vee-twin would offer all the advantages of the Musgrave engine, but would only need two simple connecting rods. The cylinders would no longer be parallel, but that is far from impractical to manufacture, as demonstrated by the even earlier diagonal engine.
Connecting rod
The two cylinders are connected to the single crankpin through a complex connecting rod of four separate links, and a rigid mounting point to the frame and cylinders.[1]
The main connecting rod is a large triangular frame, driven by both cylinders and driving the crankpin. Owing to the phase difference between the cylinders, this frame tilts back and forth as the engine rotates and so the cylinder crossheads drive it through two short connecting rods, allowing for some movement side-to-side.[2] A large rocking lever attached to the engine's frame holds the connecting rod roughly central. On the Bolton engine, this lever is extended past the frame and used to drive the condenser air pump.
Similarities to the Ross yoke
A similar mechanism appears to have been invented independently, much later on. This is the Ross yoke, invented by Andy Ross for use with Stirling engines.[3] A pair of parallel cylinders, one for the piston (driving), one containing the (driven) displacer, are connecting so that they drive back and forth with a suitable phase shift between them.
History
Marine engines
The design of the engine originated with W.Y. Fleming and P.Ferguson, marine engineers of Glasgow, in 1887.[1] It was intended for use as a marine engine, and at least 23 were supplied to ship builders requiring compact engines suitable for restricted space in engine rooms.[4]
Stationary engines
John Musgrave & Sons of the Globe Ironworks, Bolton was a mill engine builder, supplying the local cotton mills. He licensed the design in 1892, then patented further improvements to it in 1893.[1][5]
Musgrave built up to 50 of these engines, the largest offering 1,500 ihp with quadruple expansion working. Ten of these quadruple expansion, four cylinder engines were built, the remainder mostly being two-cylinder compound engines, as the Park Street Mill engine.[1] The larger engines used Corliss valves.[6]
The non-dead-centre mechanism also evened-out power as the crank rotated, making it suitable for driving dynamos for electricity generation. The engine also had relative high speed for its day, making it possible to drive dynamos directly. A 500 hp Corliss valve engine was installed for electricity generation in Southport.[7]
A poster in the Science Museum advertises engines to "Fleming, Ferguson, & Dixon's patent". These are twin-cylinder compound engines with a single semi-rotary valve per cylinder (as for Park Street Mill) and are offered in a range from 8 to 250 ihp and with speeds from 160 to 250 rpm.[5][8] Their working pressure is not specified, but the same poster also offers Lancashire boilers of up to 200 psi.
All of these engines are of robust construction, with large cast iron frames that have the cylinders cast integrally with them. The Park Street Mill engine is made from two large castings bolted together along a central plane and with the steam passages cored directly into the castings.
The crossheads are of the slipper pattern. This design has asymmetric bearing surfaces and so supports the forces better when the engine rotating in one direction than the other. They are commonly found on stationary engines that do not need to be reversed. However, in the Musgrave design, the two slideways face each other and so one of them will always be working "in reverse" to usual practice.
Patents
Surviving examples
Park Street Mill
Only one Musgrave non-dead-centre engine is known to survive, now preserved at the Bolton Steam Museum as part of the Northern Mill Engine Society collection.[11][12][13] On steam days these engines (or at least some) may be seen in action. The collection also includes two other engines built by Musgrave's, which are not non-dead-centre engines but much smaller barring engines.
Models
- A small model of a twin-cylinder compound engine is on display.[5]
- In 2009 the Model Engineer serialized the construction of a Musgrave engine, from castings supplied by the German firm of Lothar Matrian.[5]
References
- Pilling, Philip W. (1990). "Northern Mill Engine Society" (PDF). Archived from the original (PDF) on 2011-07-18. Retrieved 2009-07-04.
https://en.wikipedia.org/wiki/Musgrave_non-dead-centre_engine
ld Bess is an early beam engine built by the partnership of Boulton and Watt. The engine was constructed in 1777 and worked until 1848.[1]
The engine is most obviously known simply for being an early example of an engine built by Boulton and Watt. However it also played a far more important role in the development of steam engines for being the first engine designed to work with an early cutoff, and so to use the expansion of the steam for greater efficiency.
It is now preserved in the Power Gallery of the Science Museum, London.[2][3][4] It is the oldest surviving Watt engine, and the third-oldest surviving beam engine.[i]
Watt's previous Kinneil Engine
Watt's first engine at Kinneil in Scotland[5][6] had been unsuccessful,[7] and the parts were taken down and re-used at Boulton's Soho Manufactory in Birmingham.[1] The reworked engine was more successful there, and encouraged Boulton to invest further in this developing steam technology and in Watt's inventions.
The Manufactory had been built to use a water wheel to drive its machinery, and the site had been chosen on that basis, but there were concerns over seasonal lack of water to power the wheel.[8] Similar problems in the iron industry had inspired the development of the water-returning engine: a steam pump that could raise water to drive the wheel, in times of low water on the river. The Kinneil Engine had been built as a pump, for use in a coal mine, and so was suitable for this new task. Watt's rotative beam engine had not yet been considered and so the only way to produce rotary work to drive machinery in the Manufactory was by water power.
In 1777 Boulton and Watt decided to build a second engine for use at Soho, either to supplement the Kinneil Engine[8] or primarily to experiment with Watt's new idea of expansive working of the steam.[1] The new engine was also to be a water-returning engine[2] Like the earlier Newcomen engines, it was only capable of pumping water rather than driving machinery directly.
Working life
Construction
As early as 1769, Watt was considering the possibility of working steam expansively, as recorded in a letter of 28 May to Dr. Small.[9] Early engines were incapable of this, as they used a single valve for both inlet and exhaust. As Watt had already begun to use separate valves for each function,[1] it would now be possible to control their timing independently, i.e. to apply lead to the timing of the inlet valve. Watt decided to construct a new engine to demonstrate this principle and was confident of the substantial savings in coal consumption to be offered.[10]
Construction began in 1777 with the ordering of a 33-inch[ii] cylinder (84 cm).[1] The engine was erected and working at Soho by August, although still incomplete.
The engine always worked as a water pump and was equipped with two cast iron cylinders at opposite ends of the beam, one for the working cylinder and one for the pump. The pump cylinder was taller and thinner, of 24 inches (61 cm) diameter and 8 feet 3 inches (2.5 m) tall, designed for a working stroke 7 feet (2.1 m) within this, although only 6 feet 1 inch (1.9 m) was used in practice. The pumped water was delivered at a head of 24 feet (7.3 m).[1] The engine was later described as being of 30 hp in power.[11]
The beam was typical for early single-acting beam engines, pulling through wrought iron chains running over a curved arch-head at each end of the beam. At some later point, possibly when reconstructed after the fire, this beam was strengthened by being strutted and bridled with the additional timber and iron triangular trusses that are seen above the beam today.[7]
Beelzebub
Initial operation of the engine was unsatisfactory. Watt was away in Cornwall and Boulton wrote to him, describing the engine's actions as "very fierce".[12] His opinion was that the engine's cylinder was too large for the work expected of it. This led to it being worked at a pressure of around 5.7 psi, whereas if it were operating at 8 psi, it would be less jerky and violent. This action was so remarkable as to give the engine its initial nickname of Beelzebub.[1]
Neither Watt nor Boulton had a solution to the engine's behaviour. Watt's experience with the Chacewater engine, a rebuilt Smeaton engine, at Wheal Busy, suggested that cutoff led to a violent action. In September he recommended throttling the steam supply to the engine.[13] Boulton favoured further experimentation with cutoff (i.e. valve timing) and in 1779 suggested that a series of more scientific measurements be tried. With hindsight, Boulton's approach was the more thermodynamically efficient, although this lesson was not fully appreciated by locomotive drivers right to the end of steam power.
Fire and reconstruction
One morning in July 1778 the engine house was discovered to be on fire. The fire spread rapidly and within half an hour the roof was burned to the ground. The timberwork and soldered copper piping of the engine were also destroyed or damaged. Even the beam itself, a substantial timber construction, was "rendered unfit" by the fire. Fortunately the most important part of the engine, its cylinder, survived the fire relatively intact. Within three weeks the engine had been reconstructed and was expected to be working again shortly.[1]
While the engine had been damaged, Watt, who was once again away in Cornwall, had advised that "no repair farther that the roof ought to be gone about at present", with his intention being to reconstruct the engine in some improved manner.[1] The nature of these reconstructions, and their effectiveness, remains unclear.
By 1781, the engine had been working in its reconstructed form for some years. Whatever the improvements had been, they left Watt and Boulton still agreeing that this was, "one of the worst engines they had".[1][14]
Closure of the Mint and preservation
The engine operated at the Soho Mint in Handsworth, West Midlands, until the mint's closure in 1848. It was sold for £48, then re-sold for £58 and placed on display on an island in Derrington Pool, outside the metal-rolling works of its new owner, a Mr. Walker.[1] Although much of the Mint's coining machinery had been re-sold for further use at the new Birmingham Mint, this aged and thoroughly obsolete engine appears to have been one of the first artefacts of industrial archaeology to be deliberately preserved.
The engine was later re-sold and then presented to the Commissioners of Patents for their Patent Office Museum, which would in turn become the Science Museum in London.[1] The engine is thus not only one of the Museum's oldest exhibits, but also one of the first to enter its collection. When first displayed, the engine was erected in an open-fronted representation of a brick-built engine house.[15] It is now displayed on free-standing timberwork, allowing a closer inspection of the cylinders.
For an engine that had been described as "one of the worst engines they had" when almost new, it had a relatively long working life of over 70 years. Its name had also shifted from the violent Beelzebub to the rather more friendly Old Bess, indicating a more satisfactory performance.[16] Reports by both Joseph Harrison, Artificer of the Soho Mint[11] and William Buckle support this.[1]
In 2009 it was awarded an Engineering Heritage Award by the IMechE.[17]
Confusion between engines
Several confusions exist about this engine, and have been widely repeated.
The first of these confusions is that this was Watt's second engine (after the Kinneil engine) and the first by the Boulton and Watt partnership.[7] In fact several engines were built between 1773 (the return of the Kinneil engine to Birmingham) and the construction of Beelzebub in 1777.[18] These include such well-known engines as the 1775 38-inch blowing engine for John Wilkinson's blast furnaces at New Willey, near Broseley in Shropshire, and the 50-inch pumping engine for Bloomfield Colliery near Tipton in the West Midlands.[8][18]
The identity of Beelzebub is also confused. Some sources describe this as referring to the rebuilt Kinneil engine at Birmingham.[7] There are two pieces of evidence to support the view that Old Bess and Beelzebub are the same engine.[8] Firstly the name Beelzebub derives from its violent action when used experimentally for expansive working, an experiment applied to the engine built new in 1777.[1] Secondly Beelzebub is described as a 33-inch engine, as is Old Bess on display today. There is no record of Boulton & Watt ever building another engine of this dimension.[1]
See also
- Smethwick Engine – the oldest working Watt steam engine
References
- Engines were characterised by and often named after the diameter of their cylinder. This dimension (amongst other factors) determined their power output; whilst the working pressure and precise piston stroke length could be altered, the cylinder was fixed at manufacture.
immediately to the southwest of Kinneil House ... James Watt (1736–1819) devised his improved steam engine in 1765.
The grounds contain the ruins of James Watt's cottage
admit steam until one-fourth of the distance between it and the next valve is filled with steam, shut the valve and the steam will continue to expand and to press round the wheel with diminishing power
- Dickinson & Jenkins 1927, Chap. IX, The Single Acting Pumping Engine, pp. 111–119
- Preserved beam engines
- Stationary steam engines
- Steam engines in the Science Museum, London
- History of the steam engine
- Industrial Revolution
- James Watt
https://en.wikipedia.org/wiki/Old_Bess_(beam_engine)
A cataract was a speed governing device used for early single-acting beam engines, particularly atmospheric engines and Cornish engines. It was a kind of water clock.
The cataract is distinctly different from the centrifugal governor, in that it does not control the speed of the engine's stroke, but rather the timing between strokes.
Operation
.jpg)
The typical installation of a house-built beam engine spanned four floors. The cylinder and the engine driver's usual working position were located in the 'bottom chamber', approximately at ground level. Above this were the 'middle chamber', with the cylinder top cover and 'top nozzle' (the upper valve chest), and above that the 'top chamber' or beam chamber.[3] The cataracts were located in the lowest part of the engine house, in a chamber below the bottom chamber, along with the exhaust pipe. This space was awkward to access and not visited in normal operation.
The valve gear (or 'working gear') of a Newcomen or Cornish engine is based on the plug rod. This is a vertical rod, hung from the beam, and moving in parallel to the piston. Adjustable tappets are attached to this rod. These tappets strike long curved iron levers or 'horns' that are carried on three horizontal shafts or 'arbors'.[i] Each arbor works one of the engine's valves. For the Cornish cycles, these valves are the upper steam inlet to the top of the cylinder, the equilibrium valve that links upper and lower portions of the cylinder, and the lower exhaust and condensing water injection valves, which share an arbor.[4] Unlike most other steam engines, these engines could be run intermittently: making a single stroke before stopping and waiting for the valves to be restarted again.[5] The speed of each power stroke or 'coming indoors' was a feature of the engine and was not easily varied, but there was no need for the engines to run continuously, stroke after stroke.[4][6] This was a direct contrast to the rotative beam engine, and the rotary nature of almost all other steam engines. With the original Newcomen cycle, the speed of the return stroke varied according to the boiler pressure, although this still did not affect the strength or speed of the power stroke.[7]
Use of a cataract could allow an engine to be operated at only a third of its ungoverned speed.[8] When pumping load was variable, cataracts could also be connected and disconnected as required, allowing the engine to work at full speed for a period and then stopped in between.[9]
The cataract itself resembled a small plunger pump.[2] It was an iron box in a cistern filled with water, with a plunger or piston set in the top and pressed downwards by a weight. The water within the pump could only escape through a small tap or valve.[10][11] As the plunger gradually fell, its motion was passed upwards by a rocking lever and a rod to the valvegear in the middle chamber. Once the rod had risen sufficiently, this opened the first valve to admit steam into the upper part of the cylinder, beginning a new stroke.[ii]
Once the stroke had begun, the cataract's rocking lever was pushed downwards by the engine. This lifted the plunger, which acted as a suction pump within the cataract to refill the plunger box, through a flap valve from its surrounding cistern.[13] The cistern was kept filled with water by the pump that the engine itself was working.
The water outlet valve was controlled by a rod from the bottom chamber. This was used by the engine's driver to control the working speed, according to the work required.[13]
The cataract's actuating rod also had a screw adjuster, which acted to vary the water injection time (Newcomen) or the phasing between the inlet and exhaust valves (Cornish).[13] This could be used to give a longer and more effective condensation time, if the condensing water supply was warm, as in the Summer. This adjustment appears to have been poorly understood though, and little used by the engine drivers.[10]
Development
Early cataracts
The cataract first appeared on Newcomen engines in Cornwall, although their inventor is unknown. They were known in Smeaton's time, and they may be another of the developments to Newcomen's engine for which he was responsible.[6] James Watt encountered these on his trip to Cornwall in 1777.[14] They were of a simpler type, these early cataracts or 'jack in the box' were a simple tumbling box: a wooden box on a pivot was filled with water through an adjustable cock.[6] When the box was filled sufficiently to overbalance, the engine's injection valve would be triggered.
Watt
Boulton and Watt used the simple tumbling box design of cataract for some years afterwards, to around 1779.[15][16] After this other designs were used, including a water cataract where the same water was used and recycled continuously and also an air cataract using a circular bellows. An air cataract of this type was supplied for the Ale and Cakes Mine. The plunger pump design of cataract had appeared in Cornwall by 1785, but was not Watt's invention.[15]
Later cataracts
The term 'cataract' became a synonym for dashpot, at least where this was associated with steam engines and their governors. They were used as a damping device to avoid over-sensitivity with centrifugal governors.[17]
Cataracts were also used as an over-speed safety device for direct-acting water pumps.[iii] A seesaw or 'differential' lever was placed between the pump's piston rod and a cataract adjusted for the pump's normal working speed. If the pump suddenly accelerated, owing to the pump bursting or similar, the piston would overtake the cataract and the action of the differential lever would then close the pump's steam inlet valve and stop the pump, limiting possible damage.[18]
Open loop control
The cataract, like most regulators, is an example of a servomechanism. However unlike the better-known Watt centrifugal governor, this is an open-loop, rather than closed-loop control. The cataract runs at its own speed, but does not measure the resultant speed of the engine. The cataract has also been described as a 'water clock'.[15] This assumes that the relationship between the cataract's operation and the engine's speed is fixed, which is a valid assumption for a beam engine as the cataract controls the timing of the engine's stroke, rather than a variable power or throttle valve. Where a governor controls such a throttle valve, as for the Watt governor, the speed of the engine depends on a complex and unpredictable relation between the engine load, the valve position and the varying efficiency of the engine. Such governors must use a closed-loop control if they are to maintain an effective and precise regulation.
Synchronisation
One advantage of the independent and open loop nature of the cataract's control was that two engines could be adjusted to run in synchronisation, but in antiphase. With pumping engines, this gave a more even output to their pumping.[19]
Centrifugal governor
Although the centrifugal governor was already known from its use for water- and windmills, it was not until 1788 when Watt was the first to apply it to a steam engine.[20] This was the 'Lap Engine', an early rotative engine now preserved in the Science Museum, London.
With a rotative engine, it was necessary to control the rate at which an engine moved throughout its stroke, not merely to vary the timing between strokes. This required the use of a throttle valve in the steam supply, controlled by the governor. As the load on mill engines and similar uses could vary, closed-loop control such as the engine speed-based centrifugal governor was also needed.[20] The cataract was thus not used on rotative engines, not even where single-acting Cornish winding engines were still used in Cornwall.[21]
Cornish engines were not amenable to control by a throttle valve, as their operating cycle depended on the condensation time more than a throttled steam supply. Non-rotative beam engines also had no easy means to drive a centrifugal governor. For these reasons the cataract remained in service for as long as the Cornish engine did.[22]
Notes
- These were the type of small reciprocating pump commonly used as boiler feedwater pumps and often described as the 'Weir' type.
References
- 'Victoria' Pumping Engine, East London Waterworks, (Clark 1892, pp. 275–276)
https://en.wikipedia.org/wiki/Cataract_(beam_engine)
A centrifugal governor is a specific type of governor with a feedback system that controls the speed of an engine by regulating the flow of fuel or working fluid, so as to maintain a near-constant speed. It uses the principle of proportional control.
Centrifugal governors, also known as "centrifugal regulators" and "fly-ball governors", were invented by Christiaan Huygens and used to regulate the distance and pressure between millstones in windmills in the 17th century.[1][2] In 1788, James Watt adapted one to control his steam engine where it regulates the admission of steam into the cylinder(s),[3] a development that proved so important he is sometimes called the inventor. Centrifugal governors' widest use was on steam engines during the Steam Age in the 19th century. They are also found on stationary internal combustion engines and variously fueled turbines, and in some modern striking clocks.
A simple governor does not maintain an exact speed but a speed range, since under increasing load the governor opens the throttle as the speed (RPM) decreases.
Operation
.jpg)
The devices shown are on steam engines. Power is supplied to the governor from the engine's output shaft by a belt or chain connected to the lower belt wheel. The governor is connected to a throttle valve that regulates the flow of working fluid (steam) supplying the prime mover. As the speed of the prime mover increases, the central spindle of the governor rotates at a faster rate, and the kinetic energy of the balls increases. This allows the two masses on lever arms to move outwards and upwards against gravity. If the motion goes far enough, this motion causes the lever arms to pull down on a thrust bearing, which moves a beam linkage, which reduces the aperture of a throttle valve. The rate of working-fluid entering the cylinder is thus reduced and the speed of the prime mover is controlled, preventing over-speeding.
Mechanical stops may be used to limit the range of throttle motion, as seen near the masses in the image at right.
Non-gravitational regulation
A limitation of the two-arm, two-ball governor is its reliance on gravity, and that the governor must stay upright relative to the surface of the Earth for gravity to retract the balls when the governor slows down.
Governors can be built that do not use gravitational force, by using a single straight arm with weights on both ends, a center pivot attached to a spinning axle, and a spring that tries to force the weights towards the center of the spinning axle. The two weights on opposite ends of the pivot arm counterbalance any gravitational effects, but both weights use centrifugal force to work against the spring and attempt to rotate the pivot arm towards a perpendicular axis relative to the spinning axle.
Spring-retracted non-gravitational governors are commonly used in single-phase alternating current (AC) induction motors to turn off the starting field coil when the motor's rotational speed is high enough.
They are also commonly used in snowmobile and all-terrain vehicle (ATV) continuously variable transmissions (CVT), both to engage/disengage vehicle motion and to vary the transmission's pulley diameter ratio in relation to the engine revolutions per minute.
History
James Watt designed his first governor in 1788 following a suggestion from his business partner Matthew Boulton. It was a conical pendulum governor and one of the final series of innovations Watt had employed for steam engines. James Watt never claimed the centrifugal governor to be an invention of his own. A giant statue of Watt's governor stands at Smethwick in the English West Midlands.
Centrifugal governors are also used in many modern repeating watches to limit the speed of the striking train, so the repeater does not run too quickly.
Another kind of centrifugal governor consists of a pair of masses on a spindle inside a cylinder, the masses or the cylinder being coated with pads, somewhat like a centrifugal clutch or a drum brake. This is used in a spring-loaded record player and a spring-loaded telephone dial to limit the speed.
Dynamic systems
The centrifugal governor is often used in the cognitive sciences as an example of a dynamic system, in which the representation of information cannot be clearly separated from the operations being applied to the representation. And, because the governor is a servomechanism, its analysis in a dynamic system is not trivial. In 1868, James Clerk Maxwell wrote a famous paper "On Governors"[4] that is widely considered a classic in feedback control theory. Maxwell distinguishes moderators (a centrifugal brake) and governors which control motive power input. He considers devices by James Watt, Professor James Thomson, Fleeming Jenkin, William Thomson, Léon Foucault and Carl Wilhelm Siemens (a liquid governor).
Natural selection
In his famous 1858 paper to the Linnean Society, which led Darwin to publish On the Origin of Species, Alfred Russel Wallace used governors as a metaphor for the evolutionary principle:
The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure soon to follow.[5]
Bateson revisited the topic in his 1979 book Mind and Nature: A Necessary Unity, and other scholars have continued to explore the connection between natural selection and systems theory.[6]
Culture
A centrifugal governor is part of the city seal of Manchester, New Hampshire in the U.S. and is also used on the city flag. A 2017 effort to change the design was rejected by voters.[7]
See also
References
External links
- Media related to Centrifugal governors at Wikimedia Commons
https://en.wikipedia.org/wiki/Centrifugal_governor
Category:Rotating machines
Subcategories
This category has the following 11 subcategories, out of 11 total.
C
- Centrifuges (24 P)
E
- Rotary engines (3 C, 2 P)
F
- Flywheels (7 P)
G
- Gyroscopes (1 C, 18 P)
L
- Lathes (1 C, 20 P)
P
- Propellers (1 C, 39 P)
T
- Turrets (2 C, 4 P)
W
- Wheels (11 C, 37 P)
Pages in category "Rotating machines"
The following 10 pages are in this category, out of 10 total. This list may not reflect recent changes.
https://en.wikipedia.org/wiki/Category:Rotating_machines
A rotary union is a union that allows for rotation of the united parts. It is thus a device that provides a seal between a stationary supply passage (such as pipe or tubing) and a rotating part (such as a drum, cylinder, or spindle) to permit the flow of a fluid into and/or out of the rotating part. Fluids typically used with rotary joints and rotating unions include various heat transfer media and fluid power media such as steam, water, thermal oil, hydraulic fluid, and coolants.[2] A rotary union is sometimes referred to as a rotating union, rotary valve, swivel union, rotorseal,[3] rotary couplings, rotary joint, rotating joints, hydraulic coupling, pneumatic rotary union, through bore rotary union, air rotary union, electrical rotary union, or vacuum rotary union[4]
Function
A rotary union will lock onto an input valve while rotating to meet an outlet. During this time the liquid and/or gas will flow into the rotary union from its source and will be held within the device during its movement. This liquid and/or gas will leave the union when the valve openings meet during rotation, and more liquid and/or gas will flow into the union again for the next rotation. Often functioning under high pressure and constant movement, a rotary union is designed to rotate around an axis. A rotary union's design can be altered to change this or to increase the psi or rpm it needs to withstand as well as the number of valves required.
Composition
While rotary unions come in many shapes, sizes, and configurations, they always have the same four basic components: a housing unit, a shaft, a bearing (mechanical) (or bearings), and a seal. Rotary unions typically are constructed from stainless steel to resist rust and corrosion, but many other metals can be involved, like aluminum.
Housing
The housing is the component that holds all of the other elements of the rotary union together. The housing has an inlet port, which is a threaded port to which the hose supplying the medium will be attached. The rotary union may also have an outlet port, if the same joint is being used both to supply fluid to a roll and to remove fluid from the roll. In smaller rotary unions the housing is stationary. In larger rotary unions the housing is usually bolted to the drum or roll using a flange. In these cases the housing rotates at the same speed as the drum[5]
Shaft
The shaft is the component that carries the medium through the rotary union into the drum or roll. In many cases the shaft will turn with the drum or roll. In some cases, like in larger flanged rotary unions, the shaft may be stationary while the housing rotates. The bearings and seal are typically assembled around the shaft.
Bearing
The second most important part of the rotary union is the bearing. A rotary union may have only one bearing, but multiple bearing are much more common. Roller bearings; such as ball bearings and tapered roller bearings; or non-roller bearings, like graphite bearings and bronze bushings, may be used in a rotary union. The bearings are always used to allow a part of the joint, either the shaft or the housing, to rotate
Mechanical seal
The heart of the rotary union is the seal. The seal prevents the medium from leaking outside the rotary union while in operation. Seal types can vary from pusher-type end face mechanical seal, non-pusher type end face mechanical seal, lip seals, and o-ring seals. Most rotary unions have more than one seal.[6]
Types of rotary unions
Many rotary unions incorporate multiple ports, some of which are designed to handle different types of material simultaneously. A rotary union with a straight port transfers the substance directly through the rotary union. Other designs include an elbow port, which causes the material to flow out at an angle, and multiple ports. A multiple port rotary union looks like a perforated cylinder. At the end of the cylinder is a threaded screw with a seal or seals that lock on to it. The material being transferred flows into the cylinder and out of the input holes. In the case of a rotary union with multiple inputs, chambers separated by seals keep the materials from inadvertently mixing. This type of rotary union is often used in the manufacture of plastics and other petroleum products, for which multiple inputs may need to be streamlined, but kept separate.[citation needed]
Uses
Many assembly lines incorporate multiple rotary unions, because they are highly versatile and take up less space than other devices designed for a similar purpose. Rotary unions also appear in automobiles and other machines that require constant supplies of lubrication, air, or other liquids in order for moving parts to run smoothly. Brakes, for example, use rotary unions to maintain a constant supply of pressurized brake fluid. Rotary unions are also heavily used in crude oil processing, the chemical industry, commercial food production, and pharmaceutical applications.
Agriculture
Equipment used in grain harvesting including combines, tractors, grain carts and threshers employ rotary unions. Once harvested, many crops will be processed with equipment that uses rotary unions. Food processing equipment that use rotary unions include cooling conveyors, flaking mills, shredders, steam cookers, starch dryers, rotary cutters and roll-forming.
Automotive
Auto manufacturing is a diverse user of rotary unions for a broad range of parts or components and materials, whether machined steel, iron or aluminum, stampings, plastics, glass or paperboard. Rotary unions are used for operations that require coolant, lubricant or hydraulics.
Car washes
There are two kinds of car wash facilities that use unions: the automatic and the hand operated. Most manufacturers of automatic systems have several revolving brushes which use 55 series to introduce low pressure detergent water through the supporting shaft to the brushes. In addition, automatic car washes have spinners that require rotary unions to transmit high-pressure water into the spinning mechanisms.
Converting
Downstream processing of paper, plastic film, foil and related substrate materials into finished, printed packaging such as bags, pouches, labels, tags, folding cartons and corrugated shipping cases is called converting. Rotary unions are used in all types of converting for water, steam, thermal oil, air or hydraulics.
Machine tools
Rotary unions may be used to transmit coolant, cutting oil, MQL, pressurized air in a bearingless or bearing supported configuration. Besides coolant delivery, rotary unions are used for chucking, tool sensing, rotary index table and other machine tool applications.
Mining
Electro-hydraulic equipment used in mining operations employ rotary unions including shuttle cars and coal cars, drill heads, backhoes, clam shell cranes and drag lines. In addition, boom hoists, retrieving drums and bucket drum clutches each require rotary unions.
Oil and gas
Drilling rigs (oil or gas) use air clutches and brakes that require rotary unions. Water unions are used to flush mud from the drill tip, and must withstand shock and vibration in this severe application. Oil and petrochemical refineries use batch mixers, flaking mills, blenders and drying rolls that each require rotary unions. The development of subsea oil and gas fields requires specialized equipment. Subsea swivels, manufactured by Dynamic Sealing Technologies, Inc., are designed for deepwater oil production systems that provide equipment operations added flexibility when lowering flowlines in harsh waters down to depths reaching 3,500 meters.
Paper
Paper applications span the supply chain from the raw pulp and paper mills, to the downstream paper converters. Mills use steam joint and siphon systems and water unions for heating and cooling. Converters use rotary unions for heating and cooling rolls, as well as winders with air clutches and brakes.
Plastics
The manufacturing of plastic materials encompasses a wide variety of applications including cast film, blown film, foam, flexible and rigid sheet extrusion, single and multi-layer co-extrusion, blow molding, thermoforming, pelletizing, wire and cable, injection molding and winding. Rotary unions are used for heating or cooling the many processing rolls throughout the wide variety of applications. In addition, rotary unions for air and hydraulic service are used in winding and injection molding applications. Many of today's modern winding applications will also utilize electrical slip rings.
Printing
Printing on flexible rolls of paper or plastic films requires rotary unions for air or hydraulics, as well as chill rolls for temperature control. Web offset and sheet printing equipment use many rotary unions on the ink vibrator and chill rolls.
Rubber
Rubber is compounded on big industrial mixers which use rotary unions for water cooled rolls. Rubber extrusion is similar to plastic extrusion, with rotary unions used to cool the extruder screw.
Steel
The steel industry is one of the largest users of rotary unions primarily for continuous casting machines (CCM) which use rotary unions to cool the numerous rolls that support molten slabs as it moves by gravity through various segments onto a run-out table to downstream annealing and heat treating. The slab is formed into coil or sheet. Coil is further converted in processing centers that require hydraulic unions for actuation of mandrels.
Textiles
The textile industry is a large user of water, steam and hot oil unions. Weaving, dyeing and finishing processes are the largest users of rotary unions.
Tires
Rubber tire plants use industrial mixers, extruders, calendar train cooling stacks and rayon slashers to make tire cord. Rotary unions are used in every process for temperature control.[7]
References
- "Industries". Deublin Company. Retrieved 5 November 2013.
https://www.rix-us.com/rocky-rotary-joints/
External links
https://en.wikipedia.org/wiki/Rotary_union
The Archimedes screw, also known as the Archimedean screw, hydrodynamic screw,[1] water screw or Egyptian screw,[2] is one of the earliest hydraulic machines. Using Archimedes screws as water pumps (Archimedes screw pump (ASP)[3] or screw pump[2]) dates back many centuries.[1] As a machine used for transferring water from a low-lying body of water into irrigation ditches, water is pumped by turning a screw-shaped surface inside a pipe. In the modern world, Archimedes screw pumps are widely used in wastewater treatment plants and for dewatering low-lying regions.[1] Archimedes Screws Turbines (ASTs) are a new form of small hydroelectric powerplant that can be applied even in low head sites.[4] Archimedes screw generators operate in a wide range of flows (0.01 to 14.5 ) and heads (0.1 m to 10 m),[5][6] including low heads and moderate flow rates that is not ideal for traditional turbines and not occupied by high performance technologies.[5] The Archimedes screw is a reversible hydraulic machine, and there are several examples of Archimedes screw installations where the screw can operate at different times as either pump or generator, depending on needs for power and watercourse flow.[1]
Archimedes screw is named after Greek mathematician Archimedes who first described it around 234 BC, although there is evidence that the device had been used in Ancient Egypt long before his time.[7] A screw conveyor is a similar device which transports bulk materials such as powders and grains.
History
The screw pump is the oldest positive displacement pump.[2] The first records of a water screw, or screw pump, date back to Hellenistic Egypt before the 3rd century BC.[2][8] The Egyptian screw, used to lift water from the Nile, was composed of tubes wound round a cylinder; as the entire unit rotates, water is lifted within the spiral tube to the higher elevation. A later screw pump design from Egypt had a spiral groove cut on the outside of a solid wooden cylinder and then the cylinder was covered by boards or sheets of metal closely covering the surfaces between the grooves.[2]
Some researchers have proposed this device was used to irrigate the Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World. A cuneiform inscription of Assyrian King Sennacherib (704–681 BC) has been interpreted by Stephanie Dalley[9] to describe casting water screws in bronze some 350 years earlier. This is consistent with classical author Strabo, who describes the Hanging Gardens as irrigated by screws.[10]
The screw pump was later introduced from Egypt to Greece.[2] It was described by Archimedes,[11] on the occasion of his visit to Egypt, circa 234 BC.[12] This tradition may reflect only that the apparatus was unknown to the Greeks before Hellenistic times.[11] Archimedes never claimed credit for its invention, but it was attributed to him 200 years later by Diodorus, who believed that Archimedes invented the screw pump in Egypt.[2] Depictions of Greek and Roman water screws show them being powered by a human treading on the outer casing to turn the entire apparatus as one piece, which would require that the casing be rigidly attached to the screw.
German engineer Konrad Kyeser equipped the Archimedes screw with a crank mechanism in his Bellifortis (1405). This mechanism quickly replaced the ancient practice of working the pipe by treading.[13]
Design
The Archimedes screw consists of a screw (a helical surface surrounding a central cylindrical shaft) inside a hollow pipe. The screw is usually turned by windmill, manual labor, cattle, or by modern means, such as a motor. As the shaft turns, the bottom end scoops up a volume of water. This water is then pushed up the tube by the rotating helicoid until it pours out from the top of the tube.
It is important to note that the screw volume must not be completely filled with water; there must be a fair amount of air "scooped up" together with each scoop of water. For this reason, the pump ceases to function if the bottom of the pipe is completely submerged, so that no air can be sucked in. This is because the individual pockets of water need to be separated from each other by pockets of air, or else there would be no difference between an Archimedean screw and a (curled up) pipe, which would let the water back-flow from the top basin to the bottom basin, just like a siphon.
The contact surface between the screw and the pipe does not need to be perfectly watertight, as long as the amount of water being scooped with each turn is large compared to the amount of water leaking out of each section of the screw per turn. If water from one section leaks into the next lower one, it will be transferred upwards by the next segment of the screw.
In some designs, the screw is fused to the casing and they both rotate together, instead of the screw turning within a stationary casing. The screw could be sealed to the casing with pitch resin or other adhesive, or the screw and casing could be cast together as a single piece in bronze.
The design of the everyday Greek and Roman water screw, in contrast to the heavy bronze device of Sennacherib, with its problematic drive chains, has a powerful simplicity. A double or triple helix was built of wood strips (or occasionally bronze sheeting) around a heavy wooden pole. A cylinder was built around the helices using long, narrow boards fastened to their periphery and waterproofed with pitch.[10]
Studies shows that the volume of flow passes through Archimedes screws is a function of inlet depth, diameter and rotation speed of the screw.[6] Therefore, the following analytical equation could be used to design Archimedes screws:[1]
![{\displaystyle D_{O}={\sqrt[{3}]{\frac {16\pi Q}{\sigma \omega (2\theta _{O}-sin2\theta _{O}-\delta ^{2}(2\theta _{i}-sin(2\theta _{i}))}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/0944d6dd956206bbc71fc80861d6db2f3f7214c1)
where is in and:
: Rotation speed of the Archimedes screw (rad/s)
: Volumetric flow rate
Based on the common standards that the Archimedes screw designers use this analytical equation could be simplified as:[3]
The value of η could simply determinate using the graph[1] or graph.[3] By determination of , other design parameters of Archimedes screws can be calculated using a step-by-step analytical method.[1]
Uses
 |
The screw was used predominantly for the transport of water to irrigation systems and for dewatering mines or other low-lying areas. It was used for draining land that was underneath the sea in the Netherlands and other places in the creation of polders.
Archimedes screws are used in sewage treatment plants because they cope well with varying rates of flow and with suspended solids. An auger in a snow blower or grain elevator is essentially an Archimedes screw. Concrete mixer trucks use Archimedes screws on the inside of their drum to mix or unload material.
The principle is also found in escalators, which are Archimedes screws designed to lift fish safely from ponds and transport them to another location. This technology is used primarily at fish hatcheries, where it is desirable to minimize the physical handling of fish.
An Archimedes screw was used in the successful 2001 stabilization of the Leaning Tower of Pisa. Small amounts of subsoil saturated by groundwater were removed from far below the north side of the tower, and the weight of the tower itself corrected the lean. Archimedes screws are also used in chocolate fountains.
Archimedes Screws Turbines (ASTs) are a new form of generator for small hydroelectric powerplants that could be applied even in low-head sites. The low rotation speed of ASTs reduces negative impacts on aquatic life and fish.[4]
Variants
A screw conveyor is an Archimedes screw contained within a tube and turned by a motor so as to deliver material from one end of the conveyor to the other. It is particularly suitable for transport of granular materials such as plastic granules used in injection moulding, and cereal grains. It may also be used to transport liquids. In industrial control applications the conveyor may be used as a rotary feeder or variable rate feeder to deliver a measured rate or quantity of material into a process.
A variant of the Archimedes screw can also be found in some injection moulding machines, die casting machines and extrusion of plastics, which employ a screw of decreasing pitch to compress and melt the material. It is also used in a rotary-screw air compressor. On a much larger scale, Archimedes's screws of decreasing pitch are used for the compaction of waste material.
Reverse action
If water is fed into the top of an Archimedes screw, it will force the screw to rotate. The rotating shaft can then be used to drive an electric generator. Such an installation has the same benefits as using the screw for pumping: the ability to handle very dirty water and widely varying rates of flow at high efficiency. Settle Hydro and Torrs Hydro are two reverse screw micro hydro schemes operating in England. The screw works well as a generator at low heads, commonly found in English rivers, including the Thames, powering Windsor Castle.[14]
In 2017, the first reverse screw hydropower in the United States opened in Meriden, Connecticut.[15][16] The Meriden project was built and is operated by New England Hydropower having a nameplate capacity of 193 kW and a capacity factor of approximately 55% over a 5-year running period.
See also
- Archimedean spiral
- Screw-propelled vehicle
- SS Archimedes – the first steamship driven by a screw propeller.
- Screw (simple machine)
- Screw turbine
- Spiral pump
- Toroidal propeller
- Vitruvius
Notes
The Archimedes' screw was developed in ancient Egypt and was subsequently used by Archimedes (287–212 b.c.)
- "Meriden power plant uses Archimedes Screw Turbine". Retrieved 2017-08-01.
Sources
- YoosefDoost, A, W.-D. Lubitz: Archimedes Screw Design: An Analytical Model for Rapid Estimation of Archimedes Screw Geometry, Energies 2021. doi:10.3390/en14227812
- YoosefDoost, A, W.-D. Lubitz: Design Guideline for Hydropower Plants Using One or Multiple Archimedes Screws, Processes, 2021. doi:10.3390/pr9122128
- YoosefDoost, A, W.-D. Lubitz: Archimedes Screw Turbines: A Sustainable Development Solution for Green and Renewable Energy Generation—A Review of Potential and Design Procedures, Sustainability, 2020. doi:10.3390/su12187352.
- Yoosefdoost, A.: Archimedes Screw Generators and Hydropower Plants: A Design Guideline and Analytical Models, University of Guelph, 2022, PhD Thesis, Guelph, ON, Canada (2022).
- P. J. Kantert: "Manual for Archimedean Screw Pump", Hirthammer Verlag 2008, ISBN 978-3-88721-896-6.
- P. J. Kantert: "Praxishandbuch Schneckenpumpe", Hirthammer Verlag 2008, ISBN 978-3-88721-202-5.
- P. J. Kantert: "Praxishandbuch Schneckenpumpe" - 2nd edition 2020, DWA, ISBN 978-3-88721-888-1.
- Oleson, John Peter (1984), Greek and Roman mechanical water-lifting devices. The History of a Technology, Dordrecht: D. Reidel, ISBN 90-277-1693-5
- Oleson, John Peter (2000), "Water-Lifting", in Wikander, Örjan (ed.), Handbook of Ancient Water Technology, Technology and Change in History, vol. 2, Leiden, pp. 217–302 (242–251), ISBN 90-04-11123-9
- Nuernbergk, D. and Rorres C.: „An Analytical Model for the Water Inflow of an Archimedes Screw Used in Hydropower Generation", ASCE Journal of Hydraulic Engineering, Published: 23 July 2012
- Nuernbergk D. M.: "Wasserkraftschnecken – Berechnung und optimaler Entwurf von archimedischen Schnecken als Wasserkraftmaschine", Verlag Moritz Schäfer, Detmold, 1. Edition. 2012, 272 papes, ISBN 978-3-87696-136-1
- Rorres C.: "The turn of the Screw: Optimum design of an Archimedes Screw", ASCE Journal of Hydraulic Engineering, Volume 126, Number 1, Jan.2000, pp. 72–80
- Nagel, G.; Radlik, K.: Wasserförderschnecken – Planung, Bau und Betrieb von Wasserhebeanlagen; Udo Pfriemer Buchverlag in der Bauverlag GmbH, Wiesbaden, Berlin (1988)
- White, Lynn Jr. (1962), Medieval Technology and Social Change, Oxford: At the Clarendon Press
External links
- The Turn of the Screw: Optimal Design of an Archimedes Screw, by Chris Rorres, PhD.
- "Archimedean Screw" by Sándor Kabai, Wolfram Demonstrations Project, 2007.
- "Archimedes Screw Examples Various sources, 2021
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https://en.wikipedia.org/wiki/Archimedes%27_screw
Salamanca was the first commercially successful steam locomotive, built in 1812 by Matthew Murray of Holbeck, for the edge-railed Middleton Railway between Middleton and Leeds, England[1] and it predated Stephenson's Rocket by 17 years.[2] It was the first to have two cylinders. It was named after the Duke of Wellington's victory at the battle of Salamanca which was fought that same year.
Salamanca was also the first rack and pinion locomotive, using John Blenkinsop's patented design for rack propulsion. A single rack ran outside the narrow gauge tracks and was engaged by a large cog wheel on the left side of the locomotive. The cog wheel was driven by twin cylinders embedded into the top of the centre-flue boiler. The class was described as having two 8"×20" cylinders, driving the wheels through cranks. The piston crossheads slid in guides, rather than being controlled by a parallel motion linkage like the majority of early locomotives. The engines saw up to twenty years of service.[3]
It appears in a watercolour by George Walker (1781–1856), the first painting of a steam locomotive.[4] Four such locomotives were built for the railway. Salamanca was destroyed six years later, when its boiler exploded. According to George Stephenson, giving evidence to a committee of Parliament, the driver had tampered with the boiler's safety valve.[5]
Salamanca is probably the locomotive referred to in the September 1814 edition of Annals of Philosophy: "Some time ago a steam-engine was mounted upon wheels at Leeds, and made to move along a rail road by means of a rack wheel, dragging after it a number of waggons loaded with coals." The item continues to mention a rack locomotive about a mile north of Newcastle (Blücher at Killingworth) and one without a rack wheel (probably Puffing Billy at Wylam).[6]
A model of the locomotive, built by Murray in 1811, is part of the collection held at Leeds Industrial Museum. It is the world's oldest model locomotive.[7]
References
- "Pictures of the Day: Prince William supports Aston Villa as they play Chelsea". The Telegraph. 22 September 2021. ISSN 0307-1235. Retrieved 24 September 2021.
https://en.wikipedia.org/wiki/Salamanca_(locomotive)
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A surface condenser is a water-cooled shell and tube heat exchanger installed to condense exhaust steam from a steam turbine in thermal power stations.[1][2][3] These condensers are heat exchangers which convert steam from its gaseous to its liquid state at a pressure below atmospheric pressure. Where cooling water is in short supply, an air-cooled condenser is often used. An air-cooled condenser is however, significantly more expensive and cannot achieve as low a steam turbine exhaust pressure (and temperature) as a water-cooled surface condenser. Surface condensers are also used in applications and industries other than the condensing of steam turbine exhaust in power plants. PurposeIn thermal power plants, the purpose of a surface condenser is to condense the exhaust steam from a steam turbine to obtain maximum efficiency, and also to convert the turbine exhaust steam into pure water (referred to as steam condensate) so that it may be reused in the steam generator or boiler as boiler feed water. The steam turbine itself is a device to convert the heat in steam to mechanical power. The difference between the heat of steam per unit mass at the inlet to the turbine and the heat of steam per unit mass at the outlet from the turbine represents the heat which is converted to mechanical power. Therefore, the more the conversion of heat per pound or kilogram of steam to mechanical power in the turbine, the better is its efficiency. By condensing the exhaust steam of a turbine at a pressure below atmospheric pressure, the steam pressure drop between the inlet and exhaust of the turbine is increased, which increases the amount of heat available for conversion to mechanical power. Most of the heat liberated due to condensation of the exhaust steam is carried away by the cooling medium (water or air) used by the surface condenser. Diagram of water-cooled surface condenser Diagram of a typical water-cooled surface condenser The adjacent diagram depicts a typical water-cooled surface condenser as used in power stations to condense the exhaust steam from a steam turbine driving an electrical generator as well in other applications.[2][3][4][5] There are many fabrication design variations depending on the manufacturer, the size of the steam turbine, and other site-specific conditions. ShellThe shell is the condenser's outermost body and contains the heat exchanger tubes. The shell is fabricated from carbon steel plates and is stiffened as needed to provide rigidity for the shell. When required by the selected design, intermediate plates are installed to serve as baffle plates that provide the desired flow path of the condensing steam. The plates also provide support that help prevent sagging of long tube lengths. At the bottom of the shell, where the condensate collects, an outlet is installed. In some designs, a sump (often referred to as the hotwell) is provided. Condensate is pumped from the outlet or the hotwell for reuse as boiler feedwater. For most water-cooled surface condensers, the shell is under [partial] vacuum during normal operating conditions. Vacuum system Diagram of a typical modern injector or ejector. For a steam ejector, the motive fluid is steam. For water-cooled surface condensers, the shell's internal vacuum is most commonly supplied by and maintained by an external steam jet ejector system. Such an ejector system uses steam as the motive fluid to remove any non-condensible gases that may be present in the surface condenser. The Venturi effect, which is a particular case of Bernoulli's principle, applies to the operation of steam jet ejectors. Motor driven mechanical vacuum pumps, such as the liquid ring type, are also popular for this service. Tube sheetsAt each end of the shell, a sheet of sufficient thickness usually made of stainless steel is provided, with holes for the tubes to be inserted and rolled. The inlet end of each tube is also bellmouthed for streamlined entry of water. This is to avoid eddies at the inlet of each tube giving rise to erosion, and to reduce flow friction. Some makers also recommend plastic inserts at the entry of tubes to avoid eddies eroding the inlet end. In smaller units some manufacturers use ferrules to seal the tube ends instead of rolling. To take care of length wise expansion of tubes some designs have expansion joint between the shell and the tube sheet allowing the latter to move longitudinally. In smaller units some sag is given to the tubes to take care of tube expansion with both end water boxes fixed rigidly to the shell. TubesGenerally the tubes are made of stainless steel, copper alloys such as brass or bronze, cupro nickel, or titanium depending on several selection criteria. The use of copper bearing alloys such as brass or cupro nickel is rare in new plants, due to environmental concerns of toxic copper alloys. Also depending on the steam cycle water treatment for the boiler, it may be desirable to avoid tube materials containing copper. Titanium condenser tubes are usually the best technical choice, however the use of titanium condenser tubes has been virtually eliminated by the sharp increases in the costs for this material. The tube lengths range to about 85 ft (26 m) for modern power plants, depending on the size of the condenser. The size chosen is based on transportability from the manufacturers’ site and ease of erection at the installation site. The outer diameter of condenser tubes typically ranges from 3/4 inch to 1-1/4 inch, based on condenser cooling water friction considerations and overall condenser size. WaterboxesThe tube sheet at each end with tube ends rolled, for each end of the condenser is closed by a fabricated box cover known as a waterbox, with flanged connection to the tube sheet or condenser shell. The waterbox is usually provided with man holes on hinged covers to allow inspection and cleaning. These waterboxes on inlet side will also have flanged connections for cooling water inlet butterfly valves, small vent pipe with hand valve for air venting at higher level, and hand-operated drain valve at bottom to drain the waterbox for maintenance. Similarly on the outlet waterbox the cooling water connection will have large flanges, butterfly valves, vent connection also at higher level and drain connections at lower level. Similarly thermometer pockets are located at inlet and outlet pipes for local measurements of cooling water temperature. In smaller units, some manufacturers make the condenser shell as well as waterboxes of cast iron. CorrosionOn the cooling water side of the condenser: The tubes, the tube sheets and the water boxes may be made up of materials having different compositions and are always in contact with circulating water. This water, depending on its chemical composition, will act as an electrolyte between the metallic composition of tubes and water boxes. This will give rise to electrolytic corrosion which will start from more anodic materials first. Sea water based condensers, in particular when sea water has added chemical pollutants, have the worst corrosion characteristics. River water with pollutants are also undesirable for condenser cooling water. The corrosive effect of sea or river water has to be tolerated and remedial methods have to be adopted. One method is the use of sodium hypochlorite, or chlorine, to ensure there is no marine growth on the pipes or the tubes. This practice must be strictly regulated to make sure the circulating water returning to the sea or river source is not affected. On the steam (shell) side of the condenser: The concentration of undissolved gases is high over air zone tubes. Therefore, these tubes are exposed to higher corrosion rates. Some times these tubes are affected by stress corrosion cracking, if original stress is not fully relieved during manufacture. To overcome these effects of corrosion some manufacturers provide higher corrosive resistant tubes in this area. Effects of corrosionAs the tube ends get corroded there is the possibility of cooling water leakage to the steam side contaminating the condensed steam or condensate, which is harmful to steam generators. The other parts of water boxes may also get affected in the long run requiring repairs or replacements involving long duration shut-downs. Protection from corrosionCathodic protection is typically employed to overcome this problem. Sacrificial anodes of zinc (being cheapest) plates are mounted at suitable places inside the water boxes. These zinc plates will get corroded first being in the lowest range of anodes. Hence these zinc anodes require periodic inspection and replacement. This involves comparatively less down time. The water boxes made of steel plates are also protected inside by epoxy paint. Effects of tube side foulingAs one might expect, with millions of gallons of circulating water flowing through the condenser tubing from seawater or fresh water, anything that is contained within the water flowing through the tubes can ultimately end up on either the condenser tubesheet (discussed previously) or within the tubing itself. Tube-side fouling for surface condensers falls into five main categories; particulate fouling like silt and sediment, biofouling like slime and biofilms, scaling and crystallization such as calcium carbonate, macrofouling which can include anything from zebra mussels that can grow on the tubesheet, to wood or other debris that blocks the tubing, and finally, corrosion products (discussed previously). Depending on the extent of the fouling, the impact can be quite severe on the condenser's ability to condense the exhaust steam coming from the turbine. As fouling builds up within the tubing, an insulating effect is created and the heat-transfer characteristics of the tubes are diminished, often requiring the turbine to be slowed to a point where the condenser can handle the exhaust steam produced. Typically, this can be quite costly to power plants in the form of reduced output, increase fuel consumption and increased CO2 emissions. This "derating" of the turbine to accommodate the condenser's fouled or blocked tubing is an indication that the plant needs to clean the tubing in order to return to the turbine's nameplate capacity. A variety of methods for cleaning are available, including online and offline options, depending on the plant's site-specific conditions. Other applications of surface condensers
TestingNational and international test codes are used to standardize the procedures and definitions used in testing large condensers. In the U.S., ASME publishes several performance test codes on condensers and heat exchangers. These include ASME PTC 12.2-2010, Steam Surface Condensers, and PTC 30.1-2007, Air cooled Steam Condensers. See alsoReferencesWikimedia Commons has media related to Condensers. {{cite book}}: |author= has generic name (help)
Categories: https://en.wikipedia.org/wiki/Surface_condenser
A blowback (also blow back or blow-back) is a failure of a steam locomotive, which can be catastrophic. One type of blowback is caused when atmospheric air blows down the locomotive's chimney, causing the flow of hot gases through the boiler tubes to be reversed, with the fire itself being blown through the firehole onto the footplate, with potentially serious consequences for the crew. The risk of backdraught is higher when the locomotive enters a tunnel because of the pressure shock. Such blowbacks can be prevented by opening the blower before closing the regulator. Similar blowback can be caused by debris or other obstructions in the smokebox.[1] In the days when steam-hauled trains were common in the United Kingdom, blowbacks occurred fairly frequently. In a 1955 report on an accident near Dunstable, the Inspector wrote:[2]
He also recommended that the British Transport Commission carry out an investigation into the causes of blowbacks.[2] Blowbacks can also occur when a steam tube (or pipe) bursts in the boiler, allowing high-pressure steam to enter the firebox and thus egress onto the footplate.[1] Other potential causes are unused mining explosives in the coal used to fuel the engine, and unburnt gases collecting in the firebox and then igniting.[2] ExamplesThe 1965 Winsford railway accident was caused by a blowback.[1] Driver Wallace Oakes died as a result, and his fireman Gwilym Roberts was severely injured.[3] References
https://en.wikipedia.org/wiki/Blowback_(steam_engine) The first recorded rudimentary steam engine was the aeolipile mentioned by Vitruvius between 30 and 15 BC and, described by Heron of Alexandria in 1st-century Roman Egypt.[1] Several steam-powered devices were later experimented with or proposed, such as Taqi al-Din's steam jack, a steam turbine in 16th-century Ottoman Egypt, and Thomas Savery's steam pump in 17th-century England. In 1712, Thomas Newcomen's atmospheric engine became the first commercially successful engine using the principle of the piston and cylinder, which was the fundamental type of steam engine used until the early 20th century. The steam engine was used to pump water out of coal mines. During the Industrial Revolution, steam engines started to replace water and wind power, and eventually became the dominant source of power in the late 19th century and remaining so into the early decades of the 20th century, when the more efficient steam turbine and the internal combustion engine resulted in the rapid replacement of the steam engines. The steam turbine has become the most common method by which electrical power generators are driven.[2] Investigations are being made into the practicalities of reviving the reciprocating steam engine as the basis for the new wave of advanced steam technology. PrecursorsEarly uses of steam power The earliest known rudimentary steam engine and reaction steam turbine, the aeolipile, is described by a mathematician and engineer named Heron of Alexandria in 1st century Roman Egypt, as recorded in his manuscript Spiritalia seu Pneumatica.[3][4] The same device was also mentioned by Vitruvius in De Architectura about 100 years earlier. Steam ejected tangentially from nozzles caused a pivoted ball to rotate. Its thermal efficiency was low. This suggests that the conversion of steam pressure into mechanical movement was known in Roman Egypt in the 1st century. Heron also devised a machine that used air heated in an altar fire to displace a quantity of water from a closed vessel. The weight of the water was made to pull a hidden rope to operate temple doors.[4][5] Some historians have conflated the two inventions to assert, incorrectly, that the aeolipile was capable of useful work.[citation needed] According to William of Malmesbury, in 1125, Reims was home to a church that had an organ powered by air escaping from compression "by heated water", apparently designed and constructed by professor Gerbertus.[4][6] Among the papers of Leonardo da Vinci dating to the late 15th century is the design for a steam-powered cannon called the Architonnerre, which works by the sudden influx of hot water into a sealed, red-hot cannon.[7] A rudimentary impact steam turbine was described in 1551 by Taqi al-Din, a philosopher, astronomer and engineer in 16th century Ottoman Egypt, who described a method for rotating a spit by means of a jet of steam playing on rotary vanes around the periphery of a wheel. A similar device for rotating a spit was also later described by John Wilkins in 1648.[8] These devices were then called "mills" but are now known as steam jacks. Another similar rudimentary steam turbine is shown by Giovanni Branca, an Italian engineer, in 1629 for turning a cylindrical escapement device that alternately lifted and let fall a pair of pestles working in mortars.[9] The steam flow of these early steam turbines, however, was not concentrated and most of its energy was dissipated in all directions. This would have led to a great waste of energy and so they were never seriously considered for industrial use. In 1605, French mathematician Florence Rivault in his treatise on artillery wrote on his discovery that water, if confined in a bombshell and heated, would explode the shells.[10] In 1606, the Spaniard Jerónimo de Ayanz y Beaumont demonstrated and was granted a patent for a steam-powered water pump. The pump was successfully used to drain the inundated mines of Guadalcanal, Spain.[11] Development of the commercial steam engine"The discoveries that, when brought together by Thomas Newcomen in 1712, resulted in the steam engine were:"[12]
In 1643, Evangelista Torricelli conducted experiments on suction lift water pumps to test their limits, which was about 32 feet. (Atmospheric pressure is 32.9 feet or 10.03 meters. Vapor pressure of water lowers theoretical lift height.) He devised an experiment using a tube filled with mercury and inverted in a bowl of mercury (a barometer) and observed an empty space above the column of mercury, which he theorized contained nothing, that is, a vacuum.[13] Influenced by Torricelli, Otto von Guericke invented a vacuum pump by modifying an air pump used for pressurizing an air gun. Guericke put on a demonstration in 1654 in Magdeburg, Germany, where he was mayor. Two copper hemispheres were fitted together and air was pumped out. Weights strapped to the hemispheres could not pull them apart until the air valve was opened. The experiment was repeated in 1656 using two teams of 8 horses each, which could not separate the Magdeburg hemispheres.[13] Gaspar Schott was the first to describe the hemisphere experiment in his Mechanica Hydraulico-Pneumatica (1657).[13] After reading Schott's book, Robert Boyle built an improved vacuum pump and conducted related experiments.[13] Denis Papin became interested in using a vacuum to generate motive power while working with Christiaan Huygens and Gottfried Leibniz in Paris in 1663. Papin worked for Robert Boyle from 1676 to 1679, publishing an account of his work in Continuation of New Experiments (1680) and gave a presentation to Royal Society in 1689. From 1690 on Papin began experimenting with a piston to produce power with steam, building model steam engines. He experimented with atmospheric and pressure steam engines, publishing his results in 1707.[13] In 1663, Edward Somerset, 2nd Marquess of Worcester published a book of 100 inventions which described a method for raising water between floors employing a similar principle to that of a coffee percolator. His system was the first to separate the boiler (a heated cannon barrel) from the pumping action. Water was admitted into a reinforced barrel from a cistern, and then a valve was opened to admit steam from a separate boiler. The pressure built over the top of the water, driving it up a pipe.[14] He installed his steam-powered device on the wall of the Great Tower at Raglan Castle to supply water through the tower. The grooves in the wall where the engine was installed were still to be seen in the 19th century. However, no one was prepared to risk money for such a revolutionary concept, and without backers the machine remained undeveloped.[13][15] Samuel Morland, a mathematician and inventor who worked on pumps, left notes at the Vauxhall Ordinance Office on a steam pump design that Thomas Savery read. In 1698 Savery built a steam pump called "The Miner's Friend." It employed both vacuum and pressure. These were used for low horsepower service for a number of years.[13] Thomas Newcomen was a merchant who dealt in cast iron goods. Newcomen's engine was based on the piston and cylinder design proposed by Papin. In Newcomen's engine steam was condensed by water sprayed inside the cylinder, causing atmospheric pressure to move the piston. Newcomen's first engine installed for pumping in a mine in 1712 at Dudley Castle in Staffordshire.[13] Cylinders Denis Papin's design for a piston-and-cylinder engine, 1680. Denis Papin (22 August 1647 – c. 1712) was a French physicist, mathematician and inventor, best known for his pioneering invention of the steam digester, the forerunner of the pressure cooker. In the mid-1670s Papin collaborated with the Dutch physicist Christiaan Huygens on an engine which drove out the air from a cylinder by exploding gunpowder inside it. Realising the incompleteness of the vacuum produced by this means and on moving to England in 1680, Papin devised a version of the same cylinder that obtained a more complete vacuum from boiling water and then allowing the steam to condense; in this way he was able to raise weights by attaching the end of the piston to a rope passing over a pulley. As a demonstration model, the system worked, but in order to repeat the process, the whole apparatus had to be dismantled and reassembled. Papin quickly saw that to make an automatic cycle the steam would have to be generated separately in a boiler; however, he did not take the project further. Papin also designed a paddle boat driven by a jet playing on a mill-wheel in a combination of Taqi al Din and Savery's conceptions and he is also credited with a number of significant devices such as the safety valve. Papin's years of research into the problems of harnessing steam was to play a key part in the development of the first successful industrial engines that soon followed his death. Savery steam pumpThe first steam engine to be applied industrially was the "fire-engine" or "Miner's Friend", designed by Thomas Savery in 1698. This was a pistonless steam pump, similar to the one developed by Worcester. Savery made two key contributions that greatly improved the practicality of the design. First, in order to allow the water supply to be placed below the engine, he used condensed steam to produce a partial vacuum in the pumping reservoir (the barrel in Worcester's example), and using that to pull the water upward. Secondly, in order to rapidly cool the steam to produce the vacuum, he ran cold water over the reservoir. Operation required several valves; at the start of a cycle, when the reservoir was empty, a valve would be opened to admit steam. This valve would be closed to seal the reservoir, and the cooling water valve would be opened to condense the steam and create a partial vacuum. A supply valve would then be opened, pulling water upward into the reservoir; the typical engine could pull water up to 20 feet.[16] This was then closed, and the steam valve reopened, building pressure over the water and pumping it upward, as in the Worcester design. This cycle essentially doubled the distance that water could be pumped for any given pressure of steam, and production examples raised water about 40 feet.[16] Savery's engine solved a problem that had only recently become a serious one; raising water out of the mines in southern England as they reached greater depths. Savery's engine was somewhat less efficient than Newcomen's, but this was compensated for by the fact that the separate pump used by the Newcomen engine was inefficient, giving the two engines roughly the same efficiency of 6 million foot pounds per bushel of coal (less than 1%).[17] Nor was the Savery engine very safe because part of its cycle required steam under pressure supplied by a boiler, and given the technology of the period the pressure vessel could not be made strong enough and so was prone to explosion.[18] The explosion of one of his pumps at Broad Waters (near Wednesbury), about 1705, probably marks the end of attempts to exploit his invention.[19] The Savery engine was less expensive than Newcomen's and was produced in smaller sizes.[20] Some builders were manufacturing improved versions of the Savery engine until late in the 18th century.[17] Bento de Moura Portugal, FRS, introduced an ingenious improvement of Savery's construction "to render it capable of working itself", as described by John Smeaton in the Philosophical Transactions published in 1751.[21] Atmospheric condensing enginesNewcomen "atmospheric" engine Engraving
of Newcomen engine. This appears to be copied from a drawing in
Desaguliers' 1744 work: "A course of experimental philosophy", itself
believed to have been a reversed copy of Henry Beighton's engraving
dated 1717, that may represent what is probably the second Newcomen
engine erected around 1714 at Griff colliery, Warwickshire.[22] It was Thomas Newcomen with his "atmospheric-engine" of 1712 who can be said to have brought together most of the essential elements established by Papin in order to develop the first practical steam engine for which there could be a commercial demand. This took the shape of a reciprocating beam engine installed at surface level driving a succession of pumps at one end of the beam. The engine, attached by chains from other end of the beam, worked on the atmospheric, or vacuum principle.[23] Newcomen's design used some elements of earlier concepts. Like the Savery design, Newcomen's engine used steam, cooled with water, to create a vacuum. Unlike Savery's pump, however, Newcomen used the vacuum to pull on a piston instead of pulling on water directly. The upper end of the cylinder was open to the atmospheric pressure, and when the vacuum formed, the atmospheric pressure above the piston pushed it down into the cylinder. The piston was lubricated and sealed by a trickle of water from the same cistern that supplied the cooling water. Further, to improve the cooling effect, he sprayed water directly into the cylinder.  The piston was attached by a chain to a large pivoted beam. When the piston pulled the beam, the other side of the beam was pulled upward. This end was attached to a rod that pulled on a series of conventional pump handles in the mine. At the end of this power stroke, the steam valve was reopened, and the weight of the pump rods pulled the beam down, lifting the piston and drawing steam into the cylinder again. Using the piston and beam allowed the Newcomen engine to power pumps at different levels throughout the mine, as well as eliminating the need for any high-pressure steam. The entire system was isolated to a single building on the surface. Although inefficient and extremely heavy on coal (compared to later engines), these engines raised far greater volumes of water and from greater depths than had previously been possible.[18] Over 100 Newcomen engines were installed around England by 1735, and it is estimated that as many as 2,000 were in operation by 1800 (including Watt versions). John Smeaton made numerous improvements to the Newcomen engine, notably the seals, and by improving these was able to almost triple their efficiency. He also preferred to use wheels instead of beams for transferring power from the cylinder, which made his engines more compact. Smeaton was the first to develop a rigorous theory of steam engine design of operation. He worked backward from the intended role to calculate the amount of power that would be needed for the task, the size and speed of a cylinder that would provide it, the size of boiler needed to feed it, and the amount of fuel it would consume. These were developed empirically after studying dozens of Newcomen engines in Cornwall and Newcastle, and building an experimental engine of his own at his home in Austhorpe in 1770. By the time the Watt engine was introduced only a few years later, Smeaton had built dozens of ever-larger engines into the 100 hp range.[24] Watt's separate condenser Early Watt pumping engine. While working at the University of Glasgow as an instrument maker and repairman in 1759, James Watt was introduced to the power of steam by Professor John Robison. Fascinated, Watt took to reading everything he could on the subject, and independently developed the concept of latent heat, only recently published by Joseph Black at the same university. When Watt learned that the University owned a small working model of a Newcomen engine, he pressed to have it returned from London where it was being unsuccessfully repaired. Watt repaired the machine, but found it was barely functional even when fully repaired. After working with the design, Watt concluded that 80% of the steam used by the engine was wasted. Instead of providing motive force, it was being used to heat the cylinder. In the Newcomen design, every power stroke was started with a spray of cold water, which not only condensed the steam, but also cooled the walls of the cylinder. This heat had to be replaced before the cylinder would accept steam again. In the Newcomen engine the heat was supplied only by the steam, so when the steam valve was opened again the vast majority condensed on the cold walls as soon as it was admitted to the cylinder. It took a considerable amount of time and steam before the cylinder warmed back up and the steam started to fill it up. Watt solved the problem of the water spray by removing the cold water to a different cylinder, placed beside the power cylinder. Once the induction stroke was complete a valve was opened between the two, and any steam that entered the cylinder would condense inside this cold cylinder. This would create a vacuum that would pull more of the steam into the cylinder, and so on until the steam was mostly condensed. The valve was then closed, and operation of the main cylinder continued as it would on a conventional Newcomen engine. As the power cylinder remained at operational temperature throughout, the system was ready for another stroke as soon as the piston was pulled back to the top. Maintaining the temperature was a jacket around the cylinder where steam was admitted. Watt produced a working model in 1765. Convinced that this was a great advance, Watt entered into partnerships to provide venture capital while he worked on the design. Not content with this single improvement, Watt worked tirelessly on a series of other improvements to practically every part of the engine. Watt further improved the system by adding a small vacuum pump to pull the steam out of the cylinder into the condenser, further improving cycle times. A more radical change from the Newcomen design was closing off the top of the cylinder and introducing low-pressure steam above the piston. Now the power was not due to the difference of atmospheric pressure and the vacuum, but the pressure of the steam and the vacuum, a somewhat higher value. On the upward return stroke, the steam on top was transferred through a pipe to the underside of the piston ready to be condensed for the downward stroke. Sealing of the piston on a Newcomen engine had been achieved by maintaining a small quantity of water on its upper side. This was no longer possible in Watt's engine due to the presence of the steam. Watt spent considerable effort to find a seal that worked, eventually obtained by using a mixture of tallow and oil. The piston rod also passed through a gland on the top cylinder cover sealed in a similar way.[25] The piston sealing problem was due to having no way to produce a sufficiently round cylinder. Watt tried having cylinders bored from cast iron, but they were too out of round. Watt was forced to use a hammered iron cylinder.[26] The following quotation is from Roe (1916):
Watt finally considered the design good enough to release in 1774, and the Watt engine was released to the market. As portions of the design could be easily fitted to existing Newcomen engines, there was no need to build an entirely new engine at the mines. Instead, Watt and his business partner Matthew Boulton licensed the improvements to engine operators, charging them a portion of the money they would save in reduced fuel costs. The design was wildly successful, and the Boulton and Watt company was formed to license the design and help new manufacturers build the engines. The two would later open the Soho Foundry to produce engines of their own. In 1774, John Wilkinson invented a boring machine with the shaft holding the boring tool supported on both ends, extending through the cylinder, unlike the then used cantilevered borers. With this machine he was able to successfully bore the cylinder for Boulton and Watt's first commercial engine in 1776.[26] Watt never ceased improving his designs. This further improved the operating cycle speed, introduced governors, automatic valves, double-acting pistons, a variety of rotary power takeoffs and many other improvements. Watt's technology enabled the widespread commercial use of stationary steam engines.[27] Humphrey Gainsborough produced a model condensing steam engine in the 1760s, which he showed to Richard Lovell Edgeworth, a member of the Lunar Society. Gainsborough believed that Watt had used his ideas for the invention;[28] however, James Watt was not a member of the Lunar Society at this period and his many accounts explaining the succession of thought processes leading to the final design would tend to belie this story. Power was still limited by the low pressure, the displacement of the cylinder, combustion and evaporation rates and condenser capacity. Maximum theoretical efficiency was limited by the relatively low temperature differential on either side of the piston; this meant that for a Watt engine to provide a usable amount of power, the first production engines had to be very large, and were thus expensive to build and install. Watt double-acting and rotative enginesWatt developed a double-acting engine in which steam drove the piston in both directions, thereby increasing the engine speed and efficiency. The double-acting principle also significantly increased the output of a given physical sized engine.[29][30] Boulton & Watt developed the reciprocating engine into the rotative type. Unlike the Newcomen engine, the Watt engine could operate smoothly enough to be connected to a drive shaft – via sun and planet gears – to provide rotary power along with double-acting condensing cylinders. The earliest example was built as a demonstrator and was installed in Boulton's factory to work machines for lapping (polishing) buttons or similar. For this reason it was always known as the Lap Engine.[31][32] In early steam engines the piston is usually connected by a rod to a balanced beam, rather than directly to a flywheel, and these engines are therefore known as beam engines. Early steam engines did not provide constant enough speed for critical operations such as cotton spinning. To control speed the engine was used to pump water for a water wheel, which powered the machinery.[33][34] High-pressure enginesAs the 18th century advanced, the call was for higher pressures; this was strongly resisted by Watt who used the monopoly his patent gave him to prevent others from building high-pressure engines and using them in vehicles. He mistrusted the boiler technology of the day, the way they were constructed and the strength of the materials used. The important advantages of high-pressure engines were:
The disadvantages were:
The main difference between how high-pressure and low-pressure steam engines work is the source of the force that moves the piston. In the engines of Newcomen and Watt, it is the condensation of the steam that creates most of the pressure difference, causing atmospheric pressure (Newcomen) and low-pressure steam, seldom more than 7 psi boiler pressure,[35] plus condenser vacuum[36] (Watt), to move the piston. In a high-pressure engine, most of the pressure difference is provided by the high-pressure steam from the boiler; the low-pressure side of the piston may be at atmospheric pressure or connected to the condenser pressure. Newcomen's indicator diagram, almost all below the atmospheric line, would see a revival nearly 200 years later with the low pressure cylinder of triple expansion engines contributing about 20% of the engine power, again almost completely below the atmospheric line.[37] The first known advocate of "strong steam" was Jacob Leupold in his scheme for an engine that appeared in encyclopaedic works from c. 1725. Various projects for steam propelled boats and vehicles also appeared throughout the century, one of the most promising being the construction of Nicolas-Joseph Cugnot, who demonstrated his "fardier" (steam wagon) in 1769. Whilst the working pressure used for this vehicle is unknown, the small size of the boiler gave insufficient steam production rate to allow the fardier to advance more than a few hundred metres at a time before having to stop to raise steam. Other projects and models were proposed, but as with William Murdoch's model of 1784, many were blocked by Boulton and Watt. This did not apply in the US, and in 1788 a steamboat built by John Fitch operated in regular commercial service along the Delaware River between Philadelphia, Pennsylvania, and Burlington, New Jersey, carrying as many as 30 passengers. This boat could typically make 7 to 8 miles per hour, and traveled more than 2,000 miles (3,200 km) during its short length of service. The Fitch steamboat was not a commercial success, as this route was adequately covered by relatively good wagon roads. In 1802, William Symington built a practical steamboat, and in 1807, Robert Fulton used a Watt steam engine to power the first commercially successful steamboat.[citation needed] Oliver Evans in his turn was in favour of "strong steam" which he applied to boat engines and to stationary uses. He was a pioneer of cylindrical boilers; however, Evans' boilers did suffer several serious boiler explosions, which tended to lend weight to Watt's qualms. He founded the Pittsburgh Steam Engine Company in 1811 in Pittsburgh, Pennsylvania.[38] The company introduced high-pressure steam engines to the riverboat trade in the Mississippi watershed. The first high-pressure steam engine was invented in 1800 by Richard Trevithick.[39] The importance of raising steam under pressure (from a thermodynamic standpoint) is that it attains a higher temperature. Thus, any engine using high-pressure steam operates at a higher temperature and pressure differential than is possible with a low-pressure vacuum engine. The high-pressure engine thus became the basis for most further development of reciprocating steam technology. Even so, around the year 1800, "high pressure" amounted to what today would be considered very low pressure, i.e. 40-50 psi (276-345 kPa), the point being that the high-pressure engine in question was non-condensing, driven solely by the expansive power of the steam, and once that steam had performed work it was usually exhausted at higher-than-atmospheric pressure. The blast of the exhausting steam into the chimney could be exploited to create induced draught through the fire grate and thus increase the rate of burning, hence creating more heat in a smaller furnace, at the expense of creating back pressure on the exhaust side of the piston. On 21 February 1804, at the Penydarren ironworks at Merthyr Tydfil in South Wales, the first self-propelled railway steam engine or steam locomotive, built by Richard Trevithick, was demonstrated.[40] Cornish engine and compounding Trevithick pumping engine (Cornish system). Around 1811, Richard Trevithick was required to update a Watt pumping engine in order to adapt it to one of his new large cylindrical Cornish boilers. When Trevithick left for South America in 1816, his improvements were continued by William Sims. In a parallel, Arthur Woolf developed a compound engine with two cylinders, so that steam expanded in a high-pressure cylinder before being released into a low-pressure one. Efficiency was further improved by Samuel Groase, who insulated the boiler, engine, and pipes.[41] Steam pressure above the piston was increased eventually reaching 40 psi (0.28 MPa) or even 50 psi (0.34 MPa) and now provided much of the power for the downward stroke; at the same time condensing was improved. This considerably raised efficiency and further pumping engines on the Cornish system (often known as Cornish engines) continued to be built new throughout the 19th century. Older Watt engines were updated to conform. The take-up of these Cornish improvements was slow in textile manufacturing areas where coal was cheap, due to the higher capital cost of the engines and the greater wear that they suffered. The change only began in the 1830s, usually by compounding through adding another (high-pressure) cylinder.[42] Another limitation of early steam engines was speed variability, which made them unsuitable for many textile applications, especially spinning. In order to obtain steady speeds, early steam powered textile mills used the steam engine to pump water to a water wheel, which drove the machinery.[43] Many of these engines were supplied worldwide and gave reliable and efficient service over a great many years with greatly reduced coal consumption. Some of them were very large and the type continued to be built right down to the 1890s. Corliss engine.jpg) "Gordon's
improved Corliss valvegear", detailed view. The wrist-plate is the
central plate from which rods radiate to each of the 4 valves. The Corliss steam engine (patented 1849) was called the greatest improvement since James Watt.[44] The Corliss engine had greatly improved speed control and better efficiency, making it suitable to all sorts of industrial applications, including spinning. Corliss used separate ports for steam supply and exhaust, which prevented the exhaust from cooling the passage used by the hot steam. Corliss also used partially rotating valves that provided quick action, helping to reduce pressure losses. The valves themselves were also a source of reduced friction, especially compared to the slide valve, which typically used 10% of an engine's power.[45] Corliss used automatic variable cut off. The valve gear controlled engine speed by using the governor to vary the timing of the cut off. This was partly responsible for the efficiency improvement in addition to the better speed control. Porter-Allen high speed steam engine.jpg) Porter-Allen high speed engine. Enlarge to see the Porter governor at left front of flywheel The Porter-Allen engine, introduced in 1862, used an advanced valve gear mechanism developed for Porter by Allen, a mechanic of exceptional ability, and was at first generally known as the Allen engine. The high speed engine was a precision machine that was well balanced, achievements made possible by advancements in machine tools and manufacturing technology.[45] The high speed engine ran at piston speeds from three to five times the speed of ordinary engines. It also had low speed variability. The high speed engine was widely used in sawmills to power circular saws. Later it was used for electrical generation. The engine had several advantages. It could, in some cases, be directly coupled. If gears or belts and drums were used, they could be much smaller sizes. The engine itself was also small for the amount of power it developed.[45] Porter greatly improved the fly-ball governor by reducing the rotating weight and adding a weight around the shaft. This significantly improved speed control. Porter's governor became the leading type by 1880.[citation needed] The efficiency of the Porter-Allen engine was good, but not equal to the Corliss engine.[8] Uniflow (or unaflow) engineThe uniflow engine was the most efficient type of high-pressure engine. It was invented in 1911 and was used in ships, but was displaced by steam turbines and later marine diesel engines.[45][46][47][12] References
Bibliography
Further readingWikimedia Commons has media related to History of the steam engine.
https://en.wikipedia.org/wiki/History_of_the_steam_engine#Porter-Allen_high_speed_steam_engine https://en.wikipedia.org/wiki/Steam_locomotive_components https://en.wikipedia.org/wiki/Stationary_steam_engine https://en.wikipedia.org/wiki/Murray%27s_Hypocycloidal_Engine https://en.wikipedia.org/wiki/Richard_Trevithick#London_Steam_Carriage https://en.wikipedia.org/wiki/Lap_Engine https://en.wikipedia.org/wiki/John_Wilkinson_(industrialist)#Boring_machine_for_steam_engines
https://en.wikipedia.org/wiki/Fairbottom_Bobs https://en.wikipedia.org/wiki/Watt_steam_engine#Separate_condenser https://en.wikipedia.org/wiki/Oscillating_cylinder_steam_engine https://en.wikipedia.org/wiki/Injector https://en.wikipedia.org/wiki/Feedwater_heater https://en.wikipedia.org/wiki/Three-drum_boiler https://en.wikipedia.org/wiki/Thimble_tube_boiler https://en.wikipedia.org/wiki/Launch-type_boiler https://en.wikipedia.org/wiki/Crank_(mechanism) https://en.wikipedia.org/wiki/Beam_engine#Rotative_beam_engines https://en.wikipedia.org/wiki/Chain https://en.wikipedia.org/wiki/Parallel_motion_linkage https://en.wikipedia.org/wiki/Roller_chain https://en.wikipedia.org/wiki/List_of_boiler_types_by_manufacturer#box_boiler https://en.wikipedia.org/wiki/Water-tube_boiler https://en.wikipedia.org/wiki/Fire-tube_boiler https://en.wikipedia.org/wiki/Centrifugal_governor
https://en.wikipedia.org/wiki/Reciprocating_engine https://en.wikipedia.org/wiki/Return_connecting_rod_engine https://en.wikipedia.org/wiki/Steeple_compound_engine https://en.wikipedia.org/wiki/Six-column_beam_engine https://en.wikipedia.org/wiki/Wheal_Busy https://en.wikipedia.org/wiki/Category:Inventions_by_Christiaan_Huygens https://en.wikipedia.org/wiki/Category:Mechanical_power_control https://en.wikipedia.org/wiki/Category:Cybernetics https://en.wikipedia.org/wiki/Category:Control_devices https://en.wikipedia.org/wiki/Category:Mechanisms_(engineering) https://en.wikipedia.org/wiki/Uniflow_steam_engine https://en.wikipedia.org/wiki/Newcomen_atmospheric_engine https://en.wikipedia.org/wiki/History_of_the_steam_engine#Precursors https://en.wikipedia.org/wiki/Beam_engine#Rotative_beam_engines https://en.wikipedia.org/wiki/Sun_and_planet_gear https://en.wikipedia.org/wiki/Connecting_rod https://en.wikipedia.org/wiki/Piston_rod https://en.wikipedia.org/wiki/Internal_combustion_engine
 Diagram of a cylinder as found in an overhead cam 4-stroke gasoline engine:
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons (piston engine), turbine blades (gas turbine), a rotor (Wankel engine), or a nozzle (jet engine). This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.
The first commercially successful internal combustion engine was created by Étienne Lenoir around 1860,[1] and the first modern internal combustion engine, known as the Otto engine, was created in 1876 by Nicolaus Otto. The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar two-stroke and four-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine. A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as previously described.[1][2] Firearms are also a form of internal combustion engine,[2] though of a type so specialized that they are commonly treated as a separate category, along with weaponry such as mortars and anti-aircraft cannons. In contrast, in external combustion engines, such as steam or Stirling engines, energy is delivered to a working fluid not consisting of, mixed with, or contaminated by combustion products. Working fluids for external combustion engines include air, hot water, pressurized water or even boiler-heated liquid sodium. While there are many stationary applications, most ICEs are used in mobile applications and are the primary power supply for vehicles such as cars, aircraft and boats. ICEs are typically powered by hydrocarbon-based fuels like natural gas, gasoline, diesel fuel, or ethanol. Renewable fuels like biodiesel are used in compression ignition (CI) engines and bioethanol or ETBE (ethyl tert-butyl ether) produced from bioethanol in spark ignition (SI) engines. As early as 1900 the inventor of the diesel engine, Rudolf Diesel, was using peanut oil to run his engines.[3] Renewable fuels are commonly blended with fossil fuels. Hydrogen, which is rarely used, can be obtained from either fossil fuels or renewable energy. HistoryVarious scientists and engineers contributed to the development of internal combustion engines. In 1791, John Barber developed the gas turbine. In 1794 Thomas Mead patented a gas engine. Also in 1794, Robert Street patented an internal combustion engine, which was also the first to use liquid fuel, and built an engine around that time. In 1798, John Stevens built the first American internal combustion engine. In 1807, French engineers Nicéphore Niépce (who went on to invent photography) and Claude Niépce ran a prototype internal combustion engine, using controlled dust explosions, the Pyréolophore, which was granted a patent by Napoleon Bonaparte. This engine powered a boat on the Saône river in France.[4][5] In the same year, Swiss engineer François Isaac de Rivaz invented a hydrogen-based internal combustion engine and powered the engine by electric spark. In 1808, De Rivaz fitted his invention to a primitive working vehicle – "the world's first internal combustion powered automobile".[6] In 1823, Samuel Brown patented the first internal combustion engine to be applied industrially. In 1854 in the UK, the Italian inventors Eugenio Barsanti and Felice Matteucci obtained the certification: "Obtaining Motive Power by the Explosion of Gases". In 1857 the Great Seal Patent Office conceded them patent No.1655 for the invention of an "Improved Apparatus for Obtaining Motive Power from Gases".[7][8][9][10] Barsanti and Matteucci obtained other patents for the same invention in France, Belgium and Piedmont between 1857 and 1859.[11][12] In 1860, Belgian engineer Jean Joseph Etienne Lenoir produced a gas-fired internal combustion engine.[13] In 1864, Nicolaus Otto patented the first atmospheric gas engine. In 1872, American George Brayton invented the first commercial liquid-fueled internal combustion engine. In 1876, Nicolaus Otto began working with Gottlieb Daimler and Wilhelm Maybach, patented the compressed charge, four-cycle engine. In 1879, Karl Benz patented a reliable two-stroke gasoline engine. Later, in 1886, Benz began the first commercial production of motor vehicles with an internal combustion engine, in which a three-wheeled, four-cycle engine and chassis formed a single unit.[14] In 1892, Rudolf Diesel developed the first compressed charge, compression ignition engine. In 1926, Robert Goddard launched the first liquid-fueled rocket. In 1939, the Heinkel He 178 became the world's first jet aircraft. EtymologyAt one time, the word engine (via Old French, from Latin ingenium, "ability") meant any piece of machinery—a sense that persists in expressions such as siege engine. A "motor" (from Latin motor, "mover") is any machine that produces mechanical power. Traditionally, electric motors are not referred to as "engines"; however, combustion engines are often referred to as "motors". (An electric engine refers to a locomotive operated by electricity.) In boating, an internal combustion engine that is installed in the hull is referred to as an engine, but the engines that sit on the transom are referred to as motors.[15] Applications Reciprocating engine of a car  Diesel generator for backup power Reciprocating piston engines are by far the most common power source for land and water vehicles, including automobiles, motorcycles, ships and to a lesser extent, locomotives (some are electrical but most use diesel engines[16][17]). Rotary engines of the Wankel design are used in some automobiles, aircraft and motorcycles. These are collectively known as internal-combustion-engine vehicles (ICEV).[18] Where high power-to-weight ratios are required, internal combustion engines appear in the form of combustion turbines, or sometimes Wankel engines. Powered aircraft typically use an ICE which may be a reciprocating engine. Airplanes can instead use jet engines and helicopters can instead employ turboshafts; both of which are types of turbines. In addition to providing propulsion, airliners may employ a separate ICE as an auxiliary power unit. Wankel engines are fitted to many unmanned aerial vehicles. ICEs drive large electric generators that power electrical grids. They are found in the form of combustion turbines with a typical electrical output in the range of some 100 MW. Combined cycle power plants use the high temperature exhaust to boil and superheat water steam to run a steam turbine. Thus, the efficiency is higher because more energy is extracted from the fuel than what could be extracted by the combustion engine alone. Combined cycle power plants achieve efficiencies in the range of 50–60%. In a smaller scale, stationary engines like gas engines or diesel generators are used for backup or for providing electrical power to areas not connected to an electric grid. Small engines (usually 2‐stroke gasoline/petrol engines) are a common power source for lawnmowers, string trimmers, chain saws, leafblowers, pressure washers, snowmobiles, jet skis, outboard motors, mopeds, and motorcycles. ClassificationThere are several possible ways to classify internal combustion engines. ReciprocatingBy number of strokes:
By type of ignition:
By mechanical/thermodynamic cycle (these cycles are infrequently used but are commonly found in hybrid vehicles, along with other vehicles manufactured for fuel efficiency[20]): RotaryContinuous combustion
Reciprocating enginesStructure Bare cylinder block of a V8 engine  Piston, piston ring, gudgeon pin and connecting rod The base of a reciprocating internal combustion engine is the engine block, which is typically made of cast iron (due to its good wear resistance and low cost)[22] or aluminum. In the latter case, the cylinder liners are made of cast iron or steel,[23] or a coating such as nikasil or alusil. The engine block contains the cylinders. In engines with more than one cylinder they are usually arranged either in 1 row (straight engine) or 2 rows (boxer engine or V engine); 3 rows are occasionally used (W engine) in contemporary engines, and other engine configurations are possible and have been used. Single cylinder engines (or thumpers) are common for motorcycles and other small engines found in light machinery. On the outer side of the cylinder, passages that contain cooling fluid are cast into the engine block whereas, in some heavy duty engines, the passages are the types of removable cylinder sleeves which can be replaceable.[22] Water-cooled engines contain passages in the engine block where cooling fluid circulates (the water jacket). Some small engines are air-cooled, and instead of having a water jacket the cylinder block has fins protruding away from it to cool the engine by directly transferring heat to the air. The cylinder walls are usually finished by honing to obtain a cross hatch, which is able to retain more oil. A too rough surface would quickly harm the engine by excessive wear on the piston. The pistons are short cylindrical parts which seal one end of the cylinder from the high pressure of the compressed air and combustion products and slide continuously within it while the engine is in operation. In smaller engines, the pistons are made of aluminum; while in larger applications, they are typically made of cast iron.[22] The top wall of the piston is termed its crown and is typically flat or concave. Some two-stroke engines use pistons with a deflector head. Pistons are open at the bottom and hollow except for an integral reinforcement structure (the piston web). When an engine is working, the gas pressure in the combustion chamber exerts a force on the piston crown which is transferred through its web to a gudgeon pin. Each piston has rings fitted around its circumference that mostly prevent the gases from leaking into the crankcase or the oil into the combustion chamber.[24] A ventilation system drives the small amount of gas that escapes past the pistons during normal operation (the blow-by gases) out of the crankcase so that it does not accumulate contaminating the oil and creating corrosion.[22] In two-stroke gasoline engines the crankcase is part of the air–fuel path and due to the continuous flow of it, two-stroke engines do not need a separate crankcase ventilation system.  Valve train above a Diesel engine cylinder head. This engine uses rocker arms but no pushrods. The cylinder head is attached to the engine block by numerous bolts or studs. It has several functions. The cylinder head seals the cylinders on the side opposite to the pistons; it contains short ducts (the ports) for intake and exhaust and the associated intake valves that open to let the cylinder be filled with fresh air and exhaust valves that open to allow the combustion gases to escape. However, 2-stroke crankcase scavenged engines connect the gas ports directly to the cylinder wall without poppet valves; the piston controls their opening and occlusion instead. The cylinder head also holds the spark plug in the case of spark ignition engines and the injector for engines that use direct injection. All CI (compression ignition) engines use fuel injection, usually direct injection but some engines instead use indirect injection. SI (spark ignition) engines can use a carburetor or fuel injection as port injection or direct injection. Most SI engines have a single spark plug per cylinder but some have 2. A head gasket prevents the gas from leaking between the cylinder head and the engine block. The opening and closing of the valves is controlled by one or several camshafts and springs—or in some engines—a desmodromic mechanism that uses no springs. The camshaft may press directly the stem of the valve or may act upon a rocker arm, again, either directly or through a pushrod.  Engine block seen from below. The cylinders, oil spray nozzle and half of the main bearings are clearly visible. The crankcase is sealed at the bottom with a sump that collects the falling oil during normal operation to be cycled again. The cavity created between the cylinder block and the sump houses a crankshaft that converts the reciprocating motion of the pistons to rotational motion. The crankshaft is held in place relative to the engine block by main bearings, which allow it to rotate. Bulkheads in the crankcase form a half of every main bearing; the other half is a detachable cap. In some cases a single main bearing deck is used rather than several smaller caps. A connecting rod is connected to offset sections of the crankshaft (the crankpins) in one end and to the piston in the other end through the gudgeon pin and thus transfers the force and translates the reciprocating motion of the pistons to the circular motion of the crankshaft. The end of the connecting rod attached to the gudgeon pin is called its small end, and the other end, where it is connected to the crankshaft, the big end. The big end has a detachable half to allow assembly around the crankshaft. It is kept together to the connecting rod by removable bolts. The cylinder head has an intake manifold and an exhaust manifold attached to the corresponding ports. The intake manifold connects to the air filter directly, or to a carburetor when one is present, which is then connected to the air filter. It distributes the air incoming from these devices to the individual cylinders. The exhaust manifold is the first component in the exhaust system. It collects the exhaust gases from the cylinders and drives it to the following component in the path. The exhaust system of an ICE may also include a catalytic converter and muffler. The final section in the path of the exhaust gases is the tailpipe. 4-stroke engines Diagram showing the operation of a 4-stroke SI engine. Labels: 1 ‐ Induction 2 ‐ Compression 3 ‐ Power 4 ‐ Exhaust The top dead center (TDC) of a piston is the position where it is nearest to the valves; bottom dead center (BDC) is the opposite position where it is furthest from them. A stroke is the movement of a piston from TDC to BDC or vice versa, together with the associated process. While an engine is in operation, the crankshaft rotates continuously at a nearly constant speed. In a 4-stroke ICE, each piston experiences 2 strokes per crankshaft revolution in the following order. Starting the description at TDC, these are:[25][26]
2-stroke enginesThe defining characteristic of this kind of engine is that each piston completes a cycle every crankshaft revolution. The 4 processes of intake, compression, power and exhaust take place in only 2 strokes so that it is not possible to dedicate a stroke exclusively for each of them. Starting at TDC the cycle consists of:
While a 4-stroke engine uses the piston as a positive displacement pump to accomplish scavenging taking 2 of the 4 strokes, a 2-stroke engine uses the last part of the power stroke and the first part of the compression stroke for combined intake and exhaust. The work required to displace the charge and exhaust gases comes from either the crankcase or a separate blower. For scavenging, expulsion of burned gas and entry of fresh mix, two main approaches are described: Loop scavenging, and Uniflow scavenging. SAE news published in the 2010s that 'Loop Scavenging' is better under any circumstance than Uniflow Scavenging.[19] Crankcase scavenged Diagram of a crankcase scavenged valveless 2-stroke engine in operation Some SI engines are crankcase scavenged and do not use poppet valves. Instead, the crankcase and the part of the cylinder below the piston is used as a pump. The intake port is connected to the crankcase through a reed valve or a rotary disk valve driven by the engine. For each cylinder, a transfer port connects in one end to the crankcase and in the other end to the cylinder wall. The exhaust port is connected directly to the cylinder wall. The transfer and exhaust port are opened and closed by the piston. The reed valve opens when the crankcase pressure is slightly below intake pressure, to let it be filled with a new charge; this happens when the piston is moving upwards. When the piston is moving downwards the pressure in the crankcase increases and the reed valve closes promptly, then the charge in the crankcase is compressed. When the piston is moving downwards, it also uncovers the exhaust port and the transfer port and the higher pressure of the charge in the crankcase makes it enter the cylinder through the transfer port, blowing the exhaust gases. Lubrication is accomplished by adding 2-stroke oil to the fuel in small ratios. Petroil refers to the mix of gasoline with the aforesaid oil. This kind of 2-stroke engine has a lower efficiency than comparable 4-strokes engines and releases more polluting exhaust gases for the following conditions:
The main advantage of 2-stroke engines of this type is mechanical simplicity and a higher power-to-weight ratio than their 4-stroke counterparts. Despite having twice as many power strokes per cycle, less than twice the power of a comparable 4-stroke engine is attainable in practice. In the US, 2-stroke engines were banned for road vehicles due to the pollution. Off-road only motorcycles are still often 2-stroke but are rarely road legal. However, many thousands of 2-stroke lawn maintenance engines are in use.[citation needed] Blower scavenged Diagram of uniflow scavenging Using a separate blower avoids many of the shortcomings of crankcase scavenging, at the expense of increased complexity which means a higher cost and an increase in maintenance requirement. An engine of this type uses ports or valves for intake and valves for exhaust, except opposed piston engines, which may also use ports for exhaust. The blower is usually of the Roots-type but other types have been used too. This design is commonplace in CI engines, and has been occasionally used in SI engines. CI engines that use a blower typically use uniflow scavenging. In this design the cylinder wall contains several intake ports placed uniformly spaced along the circumference just above the position that the piston crown reaches when at BDC. An exhaust valve or several like that of 4-stroke engines is used. The final part of the intake manifold is an air sleeve that feeds the intake ports. The intake ports are placed at a horizontal angle to the cylinder wall (I.e: they are in plane of the piston crown) to give a swirl to the incoming charge to improve combustion. The largest reciprocating IC are low speed CI engines of this type; they are used for marine propulsion (see marine diesel engine) or electric power generation and achieve the highest thermal efficiencies among internal combustion engines of any kind. Some Diesel-electric locomotive engines operate on the 2-stroke cycle. The most powerful of them have a brake power of around 4.5 MW or 6,000 HP. The EMD SD90MAC class of locomotives are an example of such. The comparable class GE AC6000CW whose prime mover has almost the same brake power uses a 4-stroke engine. An example of this type of engine is the Wärtsilä-Sulzer RT-flex96-C turbocharged 2-stroke Diesel, used in large container ships. It is the most efficient and powerful reciprocating internal combustion engine in the world with a thermal efficiency over 50%.[27][28][29] For comparison, the most efficient small four-stroke engines are around 43% thermally-efficient (SAE 900648);[citation needed] size is an advantage for efficiency due to the increase in the ratio of volume to surface area. See the external links for an in-cylinder combustion video in a 2-stroke, optically accessible motorcycle engine. Historical designDugald Clerk developed the first two-cycle engine in 1879. It used a separate cylinder which functioned as a pump in order to transfer the fuel mixture to the cylinder.[19] In 1899 John Day simplified Clerk's design into the type of 2 cycle engine that is very widely used today.[30] Day cycle engines are crankcase scavenged and port timed. The crankcase and the part of the cylinder below the exhaust port is used as a pump. The operation of the Day cycle engine begins when the crankshaft is turned so that the piston moves from BDC upward (toward the head) creating a vacuum in the crankcase/cylinder area. The carburetor then feeds the fuel mixture into the crankcase through a reed valve or a rotary disk valve (driven by the engine). There are cast in ducts from the crankcase to the port in the cylinder to provide for intake and another from the exhaust port to the exhaust pipe. The height of the port in relationship to the length of the cylinder is called the "port timing". On the first upstroke of the engine there would be no fuel inducted into the cylinder as the crankcase was empty. On the downstroke, the piston now compresses the fuel mix, which has lubricated the piston in the cylinder and the bearings due to the fuel mix having oil added to it. As the piston moves downward it first uncovers the exhaust, but on the first stroke there is no burnt fuel to exhaust. As the piston moves downward further, it uncovers the intake port which has a duct that runs to the crankcase. Since the fuel mix in the crankcase is under pressure, the mix moves through the duct and into the cylinder. Because there is no obstruction in the cylinder of the fuel to move directly out of the exhaust port prior to the piston rising far enough to close the port, early engines used a high domed piston to slow down the flow of fuel. Later the fuel was "resonated" back into the cylinder using an expansion chamber design. When the piston rose close to TDC, a spark ignited the fuel. As the piston is driven downward with power, it first uncovers the exhaust port where the burned fuel is expelled under high pressure and then the intake port where the process has been completed and will keep repeating. Later engines used a type of porting devised by the Deutz company to improve performance. It was called the Schnurle Reverse Flow system. DKW licensed this design for all their motorcycles. Their DKW RT 125 was one of the first motor vehicles to achieve over 100 mpg as a result.[31] IgnitionInternal combustion engines require ignition of the mixture, either by spark ignition (SI) or compression ignition (CI). Before the invention of reliable electrical methods, hot tube and flame methods were used. Experimental engines with laser ignition have been built.[32] Spark ignition process.jpg){kind=spacer} Bosch magneto  Points and coil ignition The spark-ignition engine was a refinement of the early engines which used Hot Tube ignition. When Bosch developed the magneto it became the primary system for producing electricity to energize a spark plug.[33] Many small engines still use magneto ignition. Small engines are started by hand cranking using a recoil starter or hand crank. Prior to Charles F. Kettering of Delco's development of the automotive starter all gasoline engined automobiles used a hand crank.[34] Larger engines typically power their starting motors and ignition systems using the electrical energy stored in a lead–acid battery. The battery's charged state is maintained by an automotive alternator or (previously) a generator which uses engine power to create electrical energy storage. The battery supplies electrical power for starting when the engine has a starting motor system, and supplies electrical power when the engine is off. The battery also supplies electrical power during rare run conditions where the alternator cannot maintain more than 13.8 volts (for a common 12V automotive electrical system). As alternator voltage falls below 13.8 volts, the lead-acid storage battery increasingly picks up electrical load. During virtually all running conditions, including normal idle conditions, the alternator supplies primary electrical power. Some systems disable alternator field (rotor) power during wide-open throttle conditions. Disabling the field reduces alternator pulley mechanical loading to nearly zero, maximizing crankshaft power. In this case, the battery supplies all primary electrical power. Gasoline engines take in a mixture of air and gasoline and compress it by the movement of the piston from bottom dead center to top dead center when the fuel is at maximum compression. The reduction in the size of the swept area of the cylinder and taking into account the volume of the combustion chamber is described by a ratio. Early engines had compression ratios of 6 to 1. As compression ratios were increased, the efficiency of the engine increased as well. With early induction and ignition systems the compression ratios had to be kept low. With advances in fuel technology and combustion management, high-performance engines can run reliably at 12:1 ratio. With low octane fuel, a problem would occur as the compression ratio increased as the fuel was igniting due to the rise in temperature that resulted. Charles Kettering developed a lead additive which allowed higher compression ratios, which was progressively abandoned for automotive use from the 1970s onward, partly due to lead poisoning concerns. The fuel mixture is ignited at different progressions of the piston in the cylinder. At low rpm, the spark is timed to occur close to the piston achieving top dead center. In order to produce more power, as rpm rises the spark is advanced sooner during piston movement. The spark occurs while the fuel is still being compressed progressively more as rpm rises.[35] The necessary high voltage, typically 10,000 volts, is supplied by an induction coil or transformer. The induction coil is a fly-back system, using interruption of electrical primary system current through some type of synchronized interrupter. The interrupter can be either contact points or a power transistor. The problem with this type of ignition is that as RPM increases the availability of electrical energy decreases. This is especially a problem, since the amount of energy needed to ignite a more dense fuel mixture is higher. The result was often a high RPM misfire. Capacitor discharge ignition was developed. It produces a rising voltage that is sent to the spark plug. CD system voltages can reach 60,000 volts.[36] CD ignitions use step-up transformers. The step-up transformer uses energy stored in a capacitance to generate electric spark. With either system, a mechanical or electrical control system provides a carefully timed high-voltage to the proper cylinder. This spark, via the spark plug, ignites the air-fuel mixture in the engine's cylinders. While gasoline internal combustion engines are much easier to start in cold weather than diesel engines, they can still have cold weather starting problems under extreme conditions. For years, the solution was to park the car in heated areas. In some parts of the world, the oil was actually drained and heated overnight and returned to the engine for cold starts. In the early 1950s, the gasoline Gasifier unit was developed, where, on cold weather starts, raw gasoline was diverted to the unit where part of the fuel was burned causing the other part to become a hot vapor sent directly to the intake valve manifold. This unit was quite popular until electric engine block heaters became standard on gasoline engines sold in cold climates.[37] Compression ignition processFor ignition, diesel, PPC and HCCI engines rely solely on the high temperature and pressure created by the engine in its compression process. The compression level that occurs is usually twice or more than a gasoline engine. Diesel engines take in air only, and shortly before peak compression, spray a small quantity of diesel fuel into the cylinder via a fuel injector that allows the fuel to instantly ignite. HCCI type engines take in both air and fuel, but continue to rely on an unaided auto-combustion process, due to higher pressures and temperature. This is also why diesel and HCCI engines are more susceptible to cold-starting issues, although they run just as well in cold weather once started. Light duty diesel engines with indirect injection in automobiles and light trucks employ glowplugs (or other pre-heating: see Cummins ISB#6BT) that pre-heat the combustion chamber just before starting to reduce no-start conditions in cold weather. Most diesels also have a battery and charging system; nevertheless, this system is secondary and is added by manufacturers as a luxury for the ease of starting, turning fuel on and off (which can also be done via a switch or mechanical apparatus), and for running auxiliary electrical components and accessories. Most new engines rely on electrical and electronic engine control units (ECU) that also adjust the combustion process to increase efficiency and reduce emissions. Lubrication.jpg) Diagram of an engine using pressurized lubrication Wikimedia Commons has media related to Internal combustion piston engine lubrication systems. Surfaces in contact and relative motion to other surfaces require lubrication to reduce wear, noise and increase efficiency by reducing the power wasting in overcoming friction, or to make the mechanism work at all. Also, the lubricant used can reduce excess heat and provide additional cooling to components. At the very least, an engine requires lubrication in the following parts:
In 2-stroke crankcase scavenged engines, the interior of the crankcase, and therefore the crankshaft, connecting rod and bottom of the pistons are sprayed by the 2-stroke oil in the air-fuel-oil mixture which is then burned along with the fuel. The valve train may be contained in a compartment flooded with lubricant so that no oil pump is required. In a splash lubrication system no oil pump is used. Instead the crankshaft dips into the oil in the sump and due to its high speed, it splashes the crankshaft, connecting rods and bottom of the pistons. The connecting rod big end caps may have an attached scoop to enhance this effect. The valve train may also be sealed in a flooded compartment, or open to the crankshaft in a way that it receives splashed oil and allows it to drain back to the sump. Splash lubrication is common for small 4-stroke engines. In a forced (also called pressurized) lubrication system, lubrication is accomplished in a closed-loop which carries motor oil to the surfaces serviced by the system and then returns the oil to a reservoir. The auxiliary equipment of an engine is typically not serviced by this loop; for instance, an alternator may use ball bearings sealed with their own lubricant. The reservoir for the oil is usually the sump, and when this is the case, it is called a wet sump system. When there is a different oil reservoir the crankcase still catches it, but it is continuously drained by a dedicated pump; this is called a dry sump system. On its bottom, the sump contains an oil intake covered by a mesh filter which is connected to an oil pump then to an oil filter outside the crankcase. From there it is diverted to the crankshaft main bearings and valve train. The crankcase contains at least one oil gallery (a conduit inside a crankcase wall) to which oil is introduced from the oil filter. The main bearings contain a groove through all or half its circumference; the oil enters these grooves from channels connected to the oil gallery. The crankshaft has drillings that take oil from these grooves and deliver it to the big end bearings. All big end bearings are lubricated this way. A single main bearing may provide oil for 0, 1 or 2 big end bearings. A similar system may be used to lubricate the piston, its gudgeon pin and the small end of its connecting rod; in this system, the connecting rod big end has a groove around the crankshaft and a drilling connected to the groove which distributes oil from there to the bottom of the piston and from then to the cylinder. Other systems are also used to lubricate the cylinder and piston. The connecting rod may have a nozzle to throw an oil jet to the cylinder and bottom of the piston. That nozzle is in movement relative to the cylinder it lubricates, but always pointed towards it or the corresponding piston. Typically forced lubrication systems have a lubricant flow higher than what is required to lubricate satisfactorily, in order to assist with cooling. Specifically, the lubricant system helps to move heat from the hot engine parts to the cooling liquid (in water-cooled engines) or fins (in air-cooled engines) which then transfer it to the environment. The lubricant must be designed to be chemically stable and maintain suitable viscosities within the temperature range it encounters in the engine. Cylinder configurationCommon cylinder configurations include the straight or inline configuration, the more compact V configuration, and the wider but smoother flat or boxer configuration. Aircraft engines can also adopt a radial configuration, which allows more effective cooling. More unusual configurations such as the H, U, X, and W have also been used.  Some popular cylinder configurations: a – straight b – V c – opposed d – W Multiple cylinder engines have their valve train and crankshaft configured so that pistons are at different parts of their cycle. It is desirable to have the pistons' cycles uniformly spaced (this is called even firing) especially in forced induction engines; this reduces torque pulsations[38] and makes inline engines with more than 3 cylinders statically balanced in its primary forces. However, some engine configurations require odd firing to achieve better balance than what is possible with even firing. For instance, a 4-stroke I2 engine has better balance when the angle between the crankpins is 180° because the pistons move in opposite directions and inertial forces partially cancel, but this gives an odd firing pattern where one cylinder fires 180° of crankshaft rotation after the other, then no cylinder fires for 540°. With an even firing pattern, the pistons would move in unison and the associated forces would add. Multiple crankshaft configurations do not necessarily need a cylinder head at all because they can instead have a piston at each end of the cylinder called an opposed piston design. Because fuel inlets and outlets are positioned at opposed ends of the cylinder, one can achieve uniflow scavenging, which, as in the four-stroke engine is efficient over a wide range of engine speeds. Thermal efficiency is improved because of a lack of cylinder heads. This design was used in the Junkers Jumo 205 diesel aircraft engine, using two crankshafts at either end of a single bank of cylinders, and most remarkably in the Napier Deltic diesel engines. These used three crankshafts to serve three banks of double-ended cylinders arranged in an equilateral triangle with the crankshafts at the corners. It was also used in single-bank locomotive engines, and is still used in marine propulsion engines and marine auxiliary generators. Diesel cycle P-V diagram for the ideal Diesel cycle. The cycle follows the numbers 1–4 in clockwise direction. Most truck and automotive diesel engines use a cycle reminiscent of a four-stroke cycle, but with temperature increase by compression causing ignition, rather than needing a separate ignition system. This variation is called the diesel cycle. In the diesel cycle, diesel fuel is injected directly into the cylinder so that combustion occurs at constant pressure, as the piston moves. Otto cycleThe Otto cycle is the most common cycle for most cars' internal combustion engines that use gasoline as a fuel. It consists of the same major steps as described for the four-stroke engine: Intake, compression, ignition, expansion and exhaust. Five-stroke engineIn 1879, Nicolaus Otto manufactured and sold a double expansion engine (the double and triple expansion principles had ample usage in steam engines), with two small cylinders at both sides of a low-pressure larger cylinder, where a second expansion of exhaust stroke gas took place; the owner returned it, alleging poor performance. In 1906, the concept was incorporated in a car built by EHV (Eisenhuth Horseless Vehicle Company);[39] and in the 21st century Ilmor designed and successfully tested a 5-stroke double expansion internal combustion engine, with high power output and low SFC (Specific Fuel Consumption).[40] Six-stroke engineThe six-stroke engine was invented in 1883. Four kinds of six-stroke engines use a regular piston in a regular cylinder (Griffin six-stroke, Bajulaz six-stroke, Velozeta six-stroke and Crower six-stroke), firing every three crankshaft revolutions. These systems capture the waste heat of the four-stroke Otto cycle with an injection of air or water. The Beare Head and "piston charger" engines operate as opposed-piston engines, two pistons in a single cylinder, firing every two revolutions rather than every four like a four-stroke engine. Other cyclesThe very first internal combustion engines did not compress the mixture. The first part of the piston downstroke drew in a fuel-air mixture, then the inlet valve closed and, in the remainder of the down-stroke, the fuel-air mixture fired. The exhaust valve opened for the piston upstroke. These attempts at imitating the principle of a steam engine were very inefficient. There are a number of variations of these cycles, most notably the Atkinson and Miller cycles. Split-cycle engines separate the four strokes of intake, compression, combustion and exhaust into two separate but paired cylinders. The first cylinder is used for intake and compression. The compressed air is then transferred through a crossover passage from the compression cylinder into the second cylinder, where combustion and exhaust occur. A split-cycle engine is really an air compressor on one side with a combustion chamber on the other. Previous split-cycle engines have had two major problems—poor breathing (volumetric efficiency) and low thermal efficiency. However, new designs are being introduced that seek to address these problems. The Scuderi Engine addresses the breathing problem by reducing the clearance between the piston and the cylinder head through various turbocharging techniques. The Scuderi design requires the use of outwardly opening valves that enable the piston to move very close to the cylinder head without the interference of the valves. Scuderi addresses the low thermal efficiency via firing after top dead center (ATDC). Firing ATDC can be accomplished by using high-pressure air in the transfer passage to create sonic flow and high turbulence in the power cylinder. Combustion turbinesJet engine Turbofan jet engine Jet engines use a number of rows of fan blades to compress air which then enters a combustor where it is mixed with fuel (typically JP fuel) and then ignited. The burning of the fuel raises the temperature of the air which is then exhausted out of the engine creating thrust. A modern turbofan engine can operate at as high as 48% efficiency.[41] There are six sections to a turbofan engine:
Gas turbines Turbine power plant A gas turbine compresses air and uses it to turn a turbine. It is essentially a jet engine which directs its output to a shaft. There are three stages to a turbine: 1) air is drawn through a compressor where the temperature rises due to compression, 2) fuel is added in the combuster, and 3) hot air is exhausted through turbine blades which rotate a shaft connected to the compressor. A gas turbine is a rotary machine similar in principle to a steam turbine and it consists of three main components: a compressor, a combustion chamber, and a turbine. The temperature of the air, after being compressed in the compressor, is increased by burning fuel in it. The heated air and the products of combustion expand in a turbine, producing work output. About 2⁄3 of the work drives the compressor: the rest (about 1⁄3) is available as useful work output.[43] Gas turbines are among the most efficient internal combustion engines. The General Electric 7HA and 9HA turbine combined cycle electrical plants are rated at over 61% efficiency.[44] Brayton cycle Brayton cycle A gas turbine is a rotary machine somewhat similar in principle to a steam turbine. It consists of three main components: compressor, combustion chamber, and turbine. The air is compressed by the compressor where a temperature rise occurs. The temperature of the compressed air is further increased by combustion of injected fuel in the combustion chamber which expands the air. This energy rotates the turbine which powers the compressor via a mechanical coupling. The hot gases are then exhausted to provide thrust. Gas turbine cycle engines employ a continuous combustion system where compression, combustion, and expansion occur simultaneously at different places in the engine—giving continuous power. Notably, the combustion takes place at constant pressure, rather than with the Otto cycle, constant volume. Wankel engines The Wankel rotary cycle. The shaft turns three times for each rotation of the rotor around the lobe and once for each orbital revolution around the eccentric shaft. The Wankel engine (rotary engine) does not have piston strokes. It operates with the same separation of phases as the four-stroke engine with the phases taking place in separate locations in the engine. In thermodynamic terms it follows the Otto engine cycle, so may be thought of as a "four-phase" engine. While it is true that three power strokes typically occur per rotor revolution, due to the 3:1 revolution ratio of the rotor to the eccentric shaft, only one power stroke per shaft revolution actually occurs. The drive (eccentric) shaft rotates once during every power stroke instead of twice (crankshaft), as in the Otto cycle, giving it a greater power-to-weight ratio than piston engines. This type of engine was most notably used in the Mazda RX-8, the earlier RX-7, and other vehicle models. The engine is also used in unmanned aerial vehicles, where the small size and weight and the high power-to-weight ratio are advantageous. Forced inductionForced induction is the process of delivering compressed air to the intake of an internal combustion engine. A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air. An engine without forced induction is considered a naturally aspirated engine. Forced induction is used in the automotive and aviation industry to increase engine power and efficiency. It particularly helps aviation engines, as they need to operate at high altitude. Forced induction is achieved by a supercharger, where the compressor is directly powered from the engine shaft or, in the turbocharger, from a turbine powered by the engine exhaust. Fuels and oxidizersAll internal combustion engines depend on combustion of a chemical fuel, typically with oxygen from the air (though it is possible to inject nitrous oxide to do more of the same thing and gain a power boost). The combustion process typically results in the production of a great quantity of thermal energy, as well as the production of steam and carbon dioxide and other chemicals at very high temperature; the temperature reached is determined by the chemical make up of the fuel and oxidizers (see stoichiometry), as well as by the compression and other factors. FuelsThe most common modern fuels are made up of hydrocarbons and are derived mostly from fossil fuels (petroleum). Fossil fuels include diesel fuel, gasoline and petroleum gas, and the rarer use of propane. Except for the fuel delivery components, most internal combustion engines that are designed for gasoline use can run on natural gas or liquefied petroleum gases without major modifications. Large diesels can run with air mixed with gases and a pilot diesel fuel ignition injection. Liquid and gaseous biofuels, such as ethanol and biodiesel (a form of diesel fuel that is produced from crops that yield triglycerides such as soybean oil), can also be used. Engines with appropriate modifications can also run on hydrogen gas, wood gas, or charcoal gas, as well as from so-called producer gas made from other convenient biomass. Experiments have also been conducted using powdered solid fuels, such as the magnesium injection cycle. Presently, fuels used include:
Even fluidized metal powders and explosives have seen some use. Engines that use gases for fuel are called gas engines and those that use liquid hydrocarbons are called oil engines; however, gasoline engines are also often colloquially referred to as "gas engines" ("petrol engines" outside North America). The main limitations on fuels are that it must be easily transportable through the fuel system to the combustion chamber, and that the fuel releases sufficient energy in the form of heat upon combustion to make practical use of the engine. Diesel engines are generally heavier, noisier, and more powerful at lower speeds than gasoline engines. They are also more fuel-efficient in most circumstances and are used in heavy road vehicles, some automobiles (increasingly so for their increased fuel efficiency over gasoline engines), ships, railway locomotives, and light aircraft. Gasoline engines are used in most other road vehicles including most cars, motorcycles, and mopeds. Note that in Europe, sophisticated diesel-engined cars have taken over about 45% of the market since the 1990s. There are also engines that run on hydrogen, methanol, ethanol, liquefied petroleum gas (LPG), biodiesel, paraffin and tractor vaporizing oil (TVO). HydrogenHydrogen could eventually replace conventional fossil fuels in traditional internal combustion engines. Alternatively fuel cell technology may come to deliver its promise and the use of the internal combustion engines could even be phased out. Although there are multiple ways of producing free hydrogen, those methods require converting combustible molecules into hydrogen or consuming electric energy. Unless that electricity is produced from a renewable source—and is not required for other purposes—hydrogen does not solve any energy crisis. In many situations the disadvantage of hydrogen, relative to carbon fuels, is its storage. Liquid hydrogen has extremely low density (14 times lower than water) and requires extensive insulation—whilst gaseous hydrogen requires heavy tankage. Even when liquefied, hydrogen has a higher specific energy but the volumetric energetic storage is still roughly five times lower than gasoline. However, the energy density of hydrogen is considerably higher than that of electric batteries, making it a serious contender as an energy carrier to replace fossil fuels. The 'Hydrogen on Demand' process (see direct borohydride fuel cell) creates hydrogen as needed, but has other issues, such as the high price of the sodium borohydride that is the raw material. Oxidizers One-cylinder gasoline engine, c. 1910 Since air is plentiful at the surface of the earth, the oxidizer is typically atmospheric oxygen, which has the advantage of not being stored within the vehicle. This increases the power-to-weight and power-to-volume ratios. Other materials are used for special purposes, often to increase power output or to allow operation under water or in space.
CoolingCooling is required to remove excessive heat—high temperature can cause engine failure, usually from wear (due to high-temperature-induced failure of lubrication), cracking or warping. Two most common forms of engine cooling are air-cooled and water-cooled. Most modern automotive engines are both water and air-cooled, as the water/liquid-coolant is carried to air-cooled fins and/or fans, whereas larger engines may be singularly water-cooled as they are stationary and have a constant supply of water through water-mains or fresh-water, while most power tool engines and other small engines are air-cooled. Some engines (air or water-cooled) also have an oil cooler. In some engines, especially for turbine engine blade cooling and liquid rocket engine cooling, fuel is used as a coolant, as it is simultaneously preheated before injecting it into a combustion chamber. Starting Electric starter as used in automobiles Internal combustion engines must have their cycles started. In reciprocating engines this is accomplished by turning the crankshaft (Wankel Rotor Shaft) which induces the cycles of intake, compression, combustion, and exhaust. The first engines were started with a turn of their flywheels, while the first vehicle (the Daimler Reitwagen) was started with a hand crank. All ICE engined automobiles were started with hand cranks until Charles Kettering developed the electric starter for automobiles.[47] This method is now the most widely used, even among non-automobiles. As diesel engines have become larger and their mechanisms heavier, air starters have come into use.[48] This is due to the lack of torque in electric starters. Air starters work by pumping compressed air into the cylinders of an engine to start it turning. Two-wheeled vehicles may have their engines started in one of four ways:
There are also starters where a spring is compressed by a crank motion and then used to start an engine. Some small engines use a pull-rope mechanism called "recoil starting", as the rope rewinds itself after it has been pulled out to start the engine. This method is commonly used in pushed lawn mowers and other settings where only a small amount of torque is needed to turn an engine over. Turbine engines are frequently started by an electric motor or by compressed air. Measures of engine performanceEngine types vary greatly in a number of different ways:
Energy efficiencyOnce ignited and burnt, the combustion products—hot gases—have more available thermal energy than the original compressed fuel-air mixture (which had higher chemical energy). This available energy is manifested as a higher temperature and pressure that can be converted into kinetic energy by the engine. In a reciprocating engine, the high-pressure gases inside the cylinders drive the engine's pistons. Once the available energy has been removed, the remaining hot gases are vented (often by opening a valve or exposing the exhaust outlet) and this allows the piston to return to its previous position (top dead center, or TDC). The piston can then proceed to the next phase of its cycle, which varies between engines. Any thermal energy that is not translated into work is normally considered a waste product and is removed from the engine either by an air or liquid cooling system. Internal combustion engines are considered heat engines (since the release of chemical energy in combustion has the same effect as heat transfer into the engine) and as such their theoretical efficiency can be approximated by idealized thermodynamic cycles. The thermal efficiency of a theoretical cycle cannot exceed that of the Carnot cycle, whose efficiency is determined by the difference between the lower and upper operating temperatures of the engine. The upper operating temperature of an engine is limited by two main factors; the thermal operating limits of the materials, and the auto-ignition resistance of the fuel. All metals and alloys have a thermal operating limit, and there is significant research into ceramic materials that can be made with greater thermal stability and desirable structural properties. Higher thermal stability allows for a greater temperature difference between the lower (ambient) and upper operating temperatures, hence greater thermodynamic efficiency. Also, as the cylinder temperature rises, the fuel becomes more prone to auto-ignition. This is caused when the cylinder temperature nears the flash point of the charge. At this point, ignition can spontaneously occur before the spark plug fires, causing excessive cylinder pressures. Auto-ignition can be mitigated by using fuels with high auto-ignition resistance (octane rating), however it still puts an upper bound on the allowable peak cylinder temperature. The thermodynamic limits assume that the engine is operating under ideal conditions: a frictionless world, ideal gases, perfect insulators, and operation for infinite time. Real world applications introduce complexities that reduce efficiency. For example, a real engine runs best at a specific load, termed its power band. The engine in a car cruising on a highway is usually operating significantly below its ideal load, because it is designed for the higher loads required for rapid acceleration.[citation needed] In addition, factors such as wind resistance reduce overall system efficiency. Vehicle fuel economy is measured in miles per gallon or in liters per 100 kilometers. The volume of hydrocarbon assumes a standard energy content. Even when aided with turbochargers and stock efficiency aids, most engines retain an average efficiency of about 18–20%.[49] However, the latest technologies in Formula One engines have seen a boost in thermal efficiency past 50%.[50] There are many inventions aimed at increasing the efficiency of IC engines. In general, practical engines are always compromised by trade-offs between different properties such as efficiency, weight, power, heat, response, exhaust emissions, or noise. Sometimes economy also plays a role in not only the cost of manufacturing the engine itself, but also manufacturing and distributing the fuel. Increasing the engine's efficiency brings better fuel economy but only if the fuel cost per energy content is the same. Measures of fuel efficiency and propellant efficiencyFor stationary and shaft engines including propeller engines, fuel consumption is measured by calculating the brake specific fuel consumption, which measures the mass flow rate of fuel consumption divided by the power produced. For internal combustion engines in the form of jet engines, the power output varies drastically with airspeed and a less variable measure is used: thrust specific fuel consumption (TSFC), which is the mass of propellant needed to generate impulses that is measured in either pound force-hour or the grams of propellant needed to generate an impulse that measures one kilonewton-second. For rockets, TSFC can be used, but typically other equivalent measures are traditionally used, such as specific impulse and effective exhaust velocity. Air and noise pollution
Air pollution
Internal combustion engines such as reciprocating internal combustion engines produce air pollution emissions, due to incomplete combustion of carbonaceous fuel. The main derivatives of the process are carbon dioxide CO Carbon dioxide emissions from internal combustion engines contribute to human-induced climate change. Increasing the engine's fuel efficiency can reduce, but not eliminate, the amount of CO Not all of the fuel is completely consumed by the combustion process. A small amount of fuel is present after combustion, and some of it reacts to form oxygenates, such as formaldehyde or acetaldehyde, or hydrocarbons not originally present in the input fuel mixture. Incomplete combustion usually results from insufficient oxygen to achieve the perfect stoichiometric ratio. The flame is "quenched" by the relatively cool cylinder walls, leaving behind unreacted fuel that is expelled with the exhaust. When running at lower speeds, quenching is commonly observed in diesel (compression ignition) engines that run on natural gas. Quenching reduces efficiency and increases knocking, sometimes causing the engine to stall. Incomplete combustion also leads to the production of carbon monoxide (CO). Further chemicals released are benzene and 1,3-butadiene that are also hazardous air pollutants. Increasing the amount of air in the engine reduces emissions of
incomplete combustion products, but also promotes reaction between
oxygen and nitrogen in the air to produce nitrogen oxides (NOx). NOx is hazardous to both plant and animal health, and leads to the production of ozone (O Carbon fuels containing sulfur produce sulfur monoxides (SO) and sulfur dioxide (SO In the United States, nitrogen oxides, PM, carbon monoxide, sulfur dioxide, and ozone, are regulated as criteria air pollutants under the Clean Air Act to levels where human health and welfare are protected. Other pollutants, such as benzene and 1,3-butadiene, are regulated as hazardous air pollutants whose emissions must be lowered as much as possible depending on technological and practical considerations. NOx, carbon monoxide and other pollutants are frequently controlled via exhaust gas recirculation which returns some of the exhaust back into the engine intake. Catalytic converters are used to convert exhaust chemicals to CO Non-road enginesThe emission standards used by many countries have special requirements for non-road engines which are used by equipment and vehicles that are not operated on the public roadways. The standards are separated from the road vehicles.[51] Noise pollutionSignificant contributions to noise pollution are made by internal combustion engines. Automobile and truck traffic operating on highways and street systems produce noise, as do aircraft flights due to jet noise, particularly supersonic-capable aircraft. Rocket engines create the most intense noise. IdlingInternal combustion engines continue to consume fuel and emit pollutants while idling. Idling is reduced by stop-start systems. Carbon dioxide formationA good way to estimate the mass of carbon dioxide that is released when one litre of diesel fuel (or gasoline) is combusted can be found as follows:[52] As a good approximation the chemical formula of diesel is C The reaction of diesel combustion is given by: 2C Carbon dioxide has a molar mass of 44 g/mol as it consists of 2 atoms of oxygen (16 g/mol) and 1 atom of carbon (12 g/mol). So 12 g of carbon yields 44 g of carbon dioxide. Diesel has a density of 0.838 kg per litre. Putting everything together the mass of carbon dioxide that is produced by burning 1 litre of diesel can be calculated as:
The figure obtained with this estimation is close to the values found in the literature. For gasoline, with a density of 0.75 kg/L and a ratio of carbon to hydrogen atoms of about 6 to 14, the estimated value of carbon dioxide emission from burning 1 litre of gasoline is:
Parasitic lossThe term parasitic loss is often applied to devices that take energy from the engine in order to enhance the engine's ability to create more energy or convert energy to motion. In the internal combustion engine, almost every mechanical component, including the drivetrain, causes parasitic loss and could thus be characterized as a parasitic load. ExamplesBearings, oil pumps, piston rings, valve springs, flywheels, transmissions, driveshafts, and differentials all act as parasitic loads that rob the system of power. These parasitic loads can be divided into two categories: those inherent to the working of the engine and those drivetrain losses incurred in the systems that transfer power from the engine to the road (such as the transmission, driveshaft, differentials and axles). For example, the former category (engine parasitic loads) includes the oil pump used to lubricate the engine, which is a necessary parasite that consumes power from the engine (its host). Another example of an engine parasitic load is a supercharger, which derives its power from the engine and creates more power for the engine. The power that the supercharger consumes is parasitic loss and is usually expressed in kilowatt or horsepower. While the power that the supercharger consumes in comparison to what it generates is small, it is still measurable or calculable. One of the desirable features of a turbocharger over a supercharger is the lower parasitic loss of the former.[53] Drivetrain parasitic losses include both steady state and dynamic loads. Steady state loads occur at constant speeds and may originate in discrete components such as the torque converter, the transmission oil pump, and/or clutch drag, and in seal/bearing drag, churning of lubricant and gear windage/friction found throughout the system. Dynamic loads occur under acceleration and are caused by inertia of rotating components and/or increased friction.[54] MeasurementWhile rules of thumb such as a 15% power loss from drivetrain parasitic loads have been commonly repeated, the actual loss of energy due to parasitic loads varies between systems. It can be influenced by powertrain design, lubricant type and temperature and many other factors.[54][55] In automobiles, drivetrain loss can be quantified by measuring the difference between power measured by an engine dynamometer and a chassis dynamometer. However, this method is primarily useful for measuring steady state loads and may not accurately reflect losses due to dynamic loads.[54] More advanced methods can be used in a laboratory setting, such as measuring in-cylinder pressure measurements, flow rate and temperature at certain points, and testing of individual parts or sub-assemblies to determine friction and pumping losses.[56] For example, in a dynamometer test by Hot Rod magazine, a Ford Mustang equipped with a modified 357ci small-block Ford V8 engine and an automatic transmission had a measured drivetrain power loss averaging 33%. In the same test, a Buick equipped with a modified 455ci V8 engine and a 4-speed manual transmission was measured to have an average drivetrain power loss of 21%.[57] Laboratory testing of a heavy-duty diesel engine determined that 1.3% of the fuel energy input was lost to parasitic loads of engine accessories such as water and oil pumps.[56] ReductionAutomotive engineers and tuners commonly make design choices that reduce parasitic loads in order to improve efficiency and power output. These may involve the choice of major engine components or systems, such as the use of dry sump lubrication system over a wet sump system. Alternately, this can be effected through substitution of minor components available as aftermarket modifications, such as exchanging a directly engine-driven fan for one equipped with a fan clutch or an electric fan.[57] Another modification to reduce parasitic loss, usually seen in track-only cars, is the replacement of an engine-driven water pump for an electrical water pump.[58] The reduction in parasitic loss from these changes may be due to reduced friction or many other variables that cause the design to be more efficient.[citation needed] See also
ReferencesAfter assembling, the air-flask shall be charged to 450 lbs. pressure
Bibliography
Further reading
External linksWikimedia Commons has media related to Internal combustion engines. Wikiversity has learning resources about Internal combustion engines
https://en.wikipedia.org/wiki/Internal_combustion_engine https://en.wikipedia.org/wiki/Stroke_(engine) https://en.wikipedia.org/wiki/Working_fluid https://en.wikipedia.org/wiki/Elsecar_Heritage_Centre#Elsecar_Engine https://en.wikipedia.org/wiki/Cylinder_(locomotive) https://en.wikipedia.org/wiki/Arthur_Woolf https://en.wikipedia.org/wiki/Stationary_engine https://en.wikipedia.org/wiki/Man_engine https://en.wikipedia.org/wiki/Beam_engine#Rotative_beam_engines Technically this was still an atmospheric engine until (under subsequent patents) he enclosed the upper part of the cylinder, introducing steam to also push the piston down. This made it a true steam engine and arguably confirms him as the inventor of the steam engine. He also patented the centrifugal governor and the parallel motion. https://en.wikipedia.org/wiki/Beam_engine https://en.wikipedia.org/wiki/Line_shaft https://en.wikipedia.org/wiki/Watt_steam_engine https://en.wikipedia.org/wiki/Spallation#Nuclear_spallation https://en.wikipedia.org/wiki/Nuclear-powered_icebreaker https://en.wikipedia.org/wiki/Laser https://en.wikipedia.org/wiki/Nuclear_reactor https://en.wikipedia.org/wiki/Fusion_power https://en.wikipedia.org/wiki/Particle_accelerator https://en.wikipedia.org/wiki/Particle-beam_weapon https://en.wikipedia.org/wiki/Nuclear_pumped_laser https://en.wikipedia.org/wiki/Nuclear_fusion https://en.wikipedia.org/wiki/Collimated_beam https://en.wikipedia.org/wiki/Gab_valve_gear https://en.wikipedia.org/wiki/Bash_valve https://en.wikipedia.org/wiki/Double_beat_valve https://en.wikipedia.org/wiki/Piston_valve_(steam_engine) https://en.wikipedia.org/wiki/Slide_valve#Murdoch's_D_slide_valve https://en.wikipedia.org/wiki/Poppet_valve https://en.wikipedia.org/wiki/Abbey_Pumping_Station
https://en.wikipedia.org/wiki/Criticality_accident https://en.wikipedia.org/wiki/Microprobe https://en.wikipedia.org/wiki/Glass https://en.wikipedia.org/wiki/Gyrotron https://en.wikipedia.org/wiki/Therac-25 https://en.wikipedia.org/wiki/Gamma_ray https://en.wikipedia.org/wiki/Nuclear_physics https://en.wikipedia.org/wiki/Nuclear_and_radiation_accidents_and_incidents https://en.wikipedia.org/wiki/Collimator https://en.wikipedia.org/wiki/Triple_beam_balance https://en.wikipedia.org/wiki/Beam-powered_propulsion https://en.wikipedia.org/wiki/Chernobyl_disaster https://en.wikipedia.org/wiki/Nuclear_reaction https://en.wikipedia.org/wiki/Electron-beam_processing https://en.wikipedia.org/wiki/TAE_Technologies#The_Colliding_Beam_Fusion_Reactor_(CBFR) https://en.wikipedia.org/wiki/Cyclotron https://en.wikipedia.org/wiki/Ion_beam https://en.wikipedia.org/wiki/Inertial_confinement_fusion https://en.wikipedia.org/wiki/Thomas_Jefferson_National_Accelerator_Facility https://en.wikipedia.org/wiki/Neutral-beam_injection https://en.wikipedia.org/wiki/Irradiation https://en.wikipedia.org/wiki/Atomic_battery https://en.wikipedia.org/wiki/Direct_energy_conversion https://en.wikipedia.org/wiki/Calutron https://en.wikipedia.org/wiki/Ion_beam_analysis https://en.wikipedia.org/wiki/Larmor_precession https://en.wikipedia.org/wiki/Nuclear_thermal_rocket https://en.wikipedia.org/wiki/Neutron_generator https://en.wikipedia.org/wiki/Oganesson#Nuclear_stability_and_isotopes https://en.wikipedia.org/wiki/Colliding_beam_fusion https://en.wikipedia.org/wiki/Van_de_Graaff_generator https://en.wikipedia.org/wiki/Nuclear_microreactor https://en.wikipedia.org/wiki/Energy_amplifier https://en.wikipedia.org/wiki/Accelerator-driven_subcritical_reactor https://en.wikipedia.org/wiki/Magnetoplasmadynamic_thruster https://en.wikipedia.org/wiki/List_of_nuclear_holocaust_fiction https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion https://en.wikipedia.org/wiki/Peaceful_nuclear_explosion https://en.wikipedia.org/wiki/Superheavy_element https://en.wikipedia.org/wiki/Neutron_transport https://en.wikipedia.org/wiki/Subcritical_reactor https://en.wikipedia.org/wiki/Electron%E2%80%93ion_collider https://en.wikipedia.org/wiki/Atomic_form_factor https://en.wikipedia.org/wiki/Atom#Nuclear_properties https://en.wikipedia.org/wiki/Nuclear_resonance_vibrational_spectroscopy https://en.wikipedia.org/wiki/Nuclear_electric_rocket https://en.wikipedia.org/wiki/Fusion_rocket https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance https://en.wikipedia.org/wiki/Attenuation_coefficient https://en.wikipedia.org/wiki/Synchrotron https://en.wikipedia.org/wiki/Isotope_separation https://en.wikipedia.org/wiki/Nuclear_emulsion?wprov=srpw1_219 https://en.wikipedia.org/wiki/Projection-slice_theorem#Extension_to_fan_beam_or_cone-beam_CT https://en.wikipedia.org/wiki/List_of_hypothetical_technologies https://en.wikipedia.org/wiki/Cherenkov_radiation#Medical_imaging_of_radioisotopes_and_external_beam_radiotherapy https://en.wikipedia.org/wiki/Neutron#Neutron_beams_and_modification_of_beams_after_production https://en.wikipedia.org/wiki/Elastic_recoil_detectionhttps://en.wikipedia.org/wiki/Elastic_recoil_detection https://en.wikipedia.org/wiki/Anti-gravity https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket https://en.wikipedia.org/wiki/Nuclear_fuel_cycle https://en.wikipedia.org/wiki/Half-value_layer https://en.wikipedia.org/wiki/Radiation_hardening https://en.wikipedia.org/wiki/Cataract https://en.wikipedia.org/wiki/Skynet_(satellite) https://en.wikipedia.org/wiki/List_of_materials_analysis_methods https://en.wikipedia.org/wiki/List_of_nuclear_research_reactors https://en.wikipedia.org/wiki/Australian_Synchrotron https://en.wikipedia.org/wiki/MagBeam https://en.wikipedia.org/wiki/Gas_cluster_ion_beam https://en.wikipedia.org/wiki/Accelerator_physics#Beam_dynamics https://en.wikipedia.org/wiki/Laser_weapon#Iron_beam https://en.wikipedia.org/wiki/Pit_(nuclear_weapon) https://en.wikipedia.org/wiki/Nuclear_drip_line https://en.wikipedia.org/wiki/Laser_propulsion https://en.wikipedia.org/wiki/Proximity_effect_(electron_beam_lithography)?wprov=srpw1_216 https://en.wikipedia.org/wiki/Proton_pack https://en.wikipedia.org/wiki/Electromagnetic_spectrum https://en.wikipedia.org/wiki/Hypernucleus https://en.wikipedia.org/wiki/Liquefaction https://en.wikipedia.org/wiki/Direct_Fusion_Drive https://en.wikipedia.org/wiki/Engineering_physics https://en.wikipedia.org/wiki/List_of_accelerators_in_particle_physics https://en.wikipedia.org/wiki/Astatine https://en.wikipedia.org/wiki/Analytical_balance#Triple_beam_balance https://en.wikipedia.org/wiki/Transmission_electron_microscopy https://en.wikipedia.org/wiki/Stopping_power_(particle_radiation) https://en.wikipedia.org/wiki/Electron#Particle_beams https://en.wikipedia.org/wiki/Vacuum_tube https://en.wikipedia.org/wiki/Absorption_cross_section https://en.wikipedia.org/wiki/Inertial_electrostatic_confinement https://en.wikipedia.org/wiki/Hydrogen_fluoride_laser https://en.wikipedia.org/wiki/Ionization_chamber https://en.wikipedia.org/wiki/Radiosurgery https://en.wikipedia.org/wiki/Projection-slice_theorem https://en.wikipedia.org/wiki/On-Line_Isotope_Mass_Separator https://en.wikipedia.org/wiki/Dark-field_microscopy https://en.wikipedia.org/wiki/Ion_source https://en.wikipedia.org/wiki/Excimer_laser https://en.wikipedia.org/wiki/Cobalt-60 https://en.wikipedia.org/wiki/T2K_experiment#Neutrino_beam https://en.wikipedia.org/wiki/Muon-catalyzed_fusion https://en.wikipedia.org/wiki/RT-2PM2_Topol-M https://en.wikipedia.org/wiki/Dark-field_microscopy#Weak-beam_imaging https://en.wikipedia.org/wiki/M51_(missile) https://en.wikipedia.org/wiki/Los_Alamos_Neutron_Science_Center https://en.wikipedia.org/wiki/Extreme_Light_Infrastructure https://en.wikipedia.org/wiki/Mojang_Studios#Game_jam_games https://en.wikipedia.org/wiki/Rad_(radiation_unit) https://en.wikipedia.org/wiki/List_of_James_Bond_films https://en.wikipedia.org/wiki/Missile_guidance#Line-of-sight_beam_riding_guidance https://en.wikipedia.org/wiki/Fission_fragment_reactor https://en.wikipedia.org/wiki/National_Ignition_Facility https://en.wikipedia.org/wiki/Colloid_thruster https://en.wikipedia.org/wiki/Linear_particle_accelerator https://en.wikipedia.org/wiki/Fixed-field_alternating_gradient_accelerator https://en.wikipedia.org/wiki/Magnetic_weapon https://en.wikipedia.org/wiki/Free_neutron_decay https://en.wikipedia.org/wiki/Darmstadtium https://en.wikipedia.org/wiki/Aneutronic_fusion https://en.wikipedia.org/wiki/Mutation_breeding#Ion_beam_technology https://en.wikipedia.org/wiki/CT_scan#Artifacts https://en.wikipedia.org/wiki/Grazing_incidence_diffraction https://en.wikipedia.org/wiki/High-energy_nuclear_physics https://en.wikipedia.org/wiki/Neutron_activation_analysis https://en.wikipedia.org/wiki/Nucleon_magnetic_moment#Control_of_neutron_beams_by_magnetism https://en.wikipedia.org/wiki/Holography https://en.wikipedia.org/wiki/Betatron https://en.wikipedia.org/wiki/Krypton https://en.wikipedia.org/wiki/Synchrotron_light_source https://en.wikipedia.org/wiki/Insertion_device https://en.wikipedia.org/wiki/Free-electron_laser https://en.wikipedia.org/wiki/Optical_cavity An optical parametric oscillator (OPO) is a parametric oscillator that oscillates at optical frequencies. It converts an input laser wave (called "pump") with frequency into two output waves of lower frequency () by means of second-order nonlinear optical interaction. The sum of the output waves' frequencies is equal to the input wave frequency: .[1] For historical reasons, the two output waves are called "signal" and "idler", where the output wave with higher frequency is the "signal". A special case is the degenerate OPO, when the output frequency is one-half the pump frequency, , which can result in half-harmonic generation when signal and idler have the same polarization. The first optical parametric oscillator was demonstrated by Joseph A. Giordmaine and Robert C. Miller in 1965,[2] five years after the invention of the laser, at Bell Labs. Optical parametric oscillators are used as coherent light sources for various scientific purposes, and to generate squeezed light for quantum mechanics research. A Soviet report was also published in 1965.[3] https://en.wikipedia.org/wiki/Optical_parametric_oscillator Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds.[1][2][3] HistoryThe first nonlinear optical effect to be predicted was two-photon absorption, by Maria Goeppert Mayer for her PhD in 1931, but it remained an unexplored theoretical curiosity until 1961 and the almost simultaneous observation of two-photon absorption at Bell Labs[4] and the discovery of second-harmonic generation by Peter Franken et al. at University of Michigan, both shortly after the construction of the first laser by Theodore Maiman.[5] However, some nonlinear effects were discovered before the development of the laser.[6] The theoretical basis for many nonlinear processes were first described in Bloembergen's monograph "Nonlinear Optics".[7] https://en.wikipedia.org/wiki/Nonlinear_optics
 Simplified diagram of a multistage coilgun with three coils, a barrel, and a ferromagnetic projectile A coilgun is a type of mass driver consisting of one or more coils used as electromagnets in the configuration of a linear motor that accelerate a ferromagnetic or conducting projectile to high velocity.[1] In almost all coilgun configurations, the coils and the gun barrel are arranged on a common axis. A coilgun is not a rifle as the barrel is smoothbore (not rifled). Coilguns generally consist of one or more coils arranged along a barrel, so the path of the accelerating projectile lies along the central axis of the coils. The coils are switched on and off in a precisely timed sequence, causing the projectile to be accelerated quickly along the barrel via magnetic forces. Coilguns are distinct from railguns, as the direction of acceleration in a railgun is at right angles to the central axis of the current loop formed by the conducting rails. In addition, railguns usually require the use of sliding contacts to pass a large current through the projectile or sabot, but coilguns do not necessarily require sliding contacts.[2] While some simple coilgun concepts can use ferromagnetic projectiles or even permanent magnet projectiles, most designs for high velocities actually incorporate a coupled coil as part of the projectile. Coilguns are also distinct from gaussguns, although many works of science fiction have erroneously confused the two. A coil gun uses electromagnetic acceleration whereas gauss guns predate the idea of coil guns and instead consists of ferromagnets using a configuration similar to a Newton's Cradle to impart acceleration.[3] HistoryThe oldest electromagnetic gun came in the form of the coilgun, the first of which was invented by Norwegian scientist Kristian Birkeland at the University of Kristiania (today Oslo). The invention was officially patented in 1904, although its development reportedly started as early as 1845. According to his accounts, Birkeland accelerated a 500-gram projectile to approximately 50 metres per second (160 ft/s).[4][5][6] In 1933, Texan inventor Virgil Rigsby developed a stationary coil gun that was designed to be used similarly to a machine gun. It was powered by a large electrical motor and generator.[7] It appeared in many contemporary science publications, but never piqued the interest of any armed forces.[8] Construction
There are two main types or setups of a coilgun: single-stage and multistage. A single-stage coilgun uses one electromagnetic coil to propel a projectile. A multistage coilgun uses several electromagnetic coils in succession to progressively increase the speed of the projectile. Ferromagnetic projectiles A single stage coilgun For ferromagnetic projectiles, a single-stage coilgun can be formed by a coil of wire, an electromagnet, with a ferromagnetic projectile placed at one of its ends. This type of coilgun is formed like the solenoid used in an electromechanical relay, i.e. a current-carrying coil which will draw a ferromagnetic object through its center. A large current is pulsed through the coil of wire and a strong magnetic field forms, pulling the projectile to the center of the coil. When the projectile nears this point the electromagnet must be switched off, to prevent the projectile from becoming arrested at the center of the electromagnet. In a multistage design, further electromagnets are then used to repeat this process, progressively accelerating the projectile. In common coilgun designs, the "barrel" of the gun is made up of a track that the projectile rides on, with the driver into the magnetic coils around the track. Power is supplied to the electromagnet from some sort of fast discharge storage device, typically a battery, or capacitors (one per electromagnet), designed for fast energy discharge. A diode is used to protect polarity sensitive components (such as semiconductors or electrolytic capacitors) from damage due to inverse polarity of the voltage after turning off the coil. Many hobbyists use low-cost rudimentary designs to experiment with coilguns, for example using photoflash capacitors from a disposable camera, or a capacitor from a standard cathode-ray tube television as the energy source, and a low inductance coil to propel the projectile forward.[9][10] Non-ferromagnetic projectilesSome designs have non-ferromagnetic projectiles, of materials such as aluminium or copper, with the armature of the projectile acting as an electromagnet with internal current induced by pulses of the acceleration coils.[11][12] A superconducting coilgun called a quench gun could be created by successively quenching a line of adjacent coaxial superconducting coils forming a gun barrel, generating a wave of magnetic field gradient traveling at any desired speed. A traveling superconducting coil might be made to ride this wave like a surfboard. The device would be a mass driver or linear synchronous motor with the propulsion energy stored directly in the drive coils.[13] Another method would have non-superconducting acceleration coils and propulsion energy stored outside them but a projectile with superconducting magnets.[14] Though the cost of power switching and other factors can limit projectile energy, a notable benefit of some coilgun designs over simpler railguns is avoiding an intrinsic velocity limit from hypervelocity physical contact and erosion. By having the projectile pulled towards or levitated within the center of the coils as it is accelerated, no physical friction with the walls of the bore occurs. If the bore is a total vacuum (such as a tube with a plasma window), there is no friction at all, which helps prolong the period of reusability.[14][15] Switching A multistage coilgun One main obstacle in coilgun design is switching the power through the coils. There are several common solutions—the simplest (and probably least effective) is the spark gap, which releases the stored energy through the coil when the voltage reaches a certain threshold. A better option is to use solid-state switches; these include IGBTs or power MOSFETs (which can be switched off mid-pulse) and SCRs (which release all stored energy before turning off).[16] A quick-and-dirty method for switching, especially for those using a flash camera for the main components, is to use the flash tube itself as a switch. By wiring it in series with the coil, it can silently and non-destructively (assuming that the energy in the capacitor is kept below the tube's safe operating limits) allow a large amount of current to pass through to the coil. Like any flash tube, ionizing the gas in the tube with a high voltage triggers it. However, a large amount of the energy will be dissipated as heat and light, and, because of the tube being a spark gap, the tube will stop conducting once the voltage across it drops sufficiently, leaving some charge remaining on the capacitor. ResistanceThe electrical resistance of the coils and the equivalent series resistance (ESR) of the current source dissipate considerable power. At low speeds the heating of the coils dominates the efficiency of the coilgun, giving exceptionally low efficiency. However, as speeds climb, mechanical power grows proportional to the square of the speed, but, correctly switched, the resistive losses are largely unaffected, and thus these resistive losses become much smaller in percentage terms. Magnetic circuitIdeally, 100% of the magnetic flux generated by the coil would be delivered to and act on the projectile; in reality this is impossible due to energy losses always present in a real system, which cannot be eliminated. With a simple air-cored solenoid, the majority of the magnetic flux is not coupled into the projectile because of the magnetic circuit's high reluctance. The uncoupled flux generates a magnetic field that stores energy in the surrounding air. The energy that is stored in this field does not simply disappear from the magnetic circuit once the capacitor finishes discharging, instead returning to the coilgun's electric circuit. Because the coilgun's electric circuit is inherently analogous to an LC oscillator, the unused energy returns in the reverse direction ('ringing'), which can seriously damage polarized capacitors such as electrolytic capacitors. Reverse charging can be prevented by a diode connected in reverse-parallel across the capacitor terminals; as a result, the current keeps flowing until the diode and the coil's resistance dissipate the field energy as heat. While this is a simple and frequently utilized solution, it requires an additional expensive high-power diode and a well-designed coil with enough thermal mass and heat dissipation capability in order to prevent component failure. Some designs attempt to recover the energy stored in the magnetic field by using a pair of diodes. These diodes, instead of being forced to dissipate the remaining energy, recharge the capacitors with the right polarity for the next discharge cycle. This will also avoid the need to fully recharge the capacitors, thus significantly reducing charge times. However, the practicality of this solution is limited by the resulting high recharge current through the equivalent series resistance (ESR) of the capacitors; the ESR will dissipate some of the recharge current, generating heat within the capacitors and potentially shortening their lifetime. To reduce component size, weight, durability requirements, and most importantly, cost, the magnetic circuit must be optimized to deliver more energy to the projectile for a given energy input. This has been addressed to some extent by the use of back iron and end iron, which are pieces of magnetic material that enclose the coil and create paths of lower reluctance in order to improve the amount of magnetic flux coupled into the projectile. Results can vary widely, depending on the materials used; hobbyist designs may use, for example, materials ranging anywhere from magnetic steel (more effective, lower reluctance) to video tape (little improvement in reluctance). Moreover, the additional pieces of magnetic material in the magnetic circuit can potentially exacerbate the possibility of flux saturation and other magnetic losses. Ferromagnetic projectile saturationAnother significant limitation of the coilgun is the occurrence of magnetic saturation in the ferromagnetic projectile. When the flux in the projectile lies in the linear portion of its material's B(H) curve, the force applied to the core is proportional to the square of coil current (I)—the field (H) is linearly dependent on I, B is linearly dependent on H and force is linearly dependent on the product BI. This relationship continues until the core is saturated; once this happens B will only increase marginally with H (and thus with I), so force gain is linear. Since losses are proportional to I2, increasing current beyond this point eventually decreases efficiency although it may increase the force. This puts an absolute limit on how much a given projectile can be accelerated with a single stage at acceptable efficiency. Projectile magnetization and reaction timeApart from saturation, the B(H) dependency often contains a hysteresis loop and the reaction time of the projectile material may be significant. The hysteresis means that the projectile becomes permanently magnetized and some energy will be lost as a permanent magnetic field of the projectile. The projectile reaction time, on the other hand, makes the projectile reluctant to respond to abrupt B changes; the flux will not rise as fast as desired while current is applied and a B tail will occur after the coil field has disappeared. This delay decreases the force, which would be maximized if the H and B were in phase. Induction coilgunsMost of the work to develop coilguns as hyper-velocity launchers has used "air-cored" systems to get around the limitations associated with ferromagnetic projectiles. In these systems, the projectile is accelerated by a moving coil "armature". If the armature is configured as one or more "shorted turns" then induced currents will result as a consequence of the time variation of the current in the static launcher coil (or coils). In principle, coilguns can also be constructed in which the moving coils are fed with current via sliding contacts. However, the practical construction of such arrangements requires the provision of reliable high speed sliding contacts. Although feeding current to a multi-turn coil armature might not require currents as large as those required in a railgun, the elimination of the need for high speed sliding contacts is an obvious potential advantage of the induction coilgun relative to the railgun. Air cored systems also introduce the penalty that much higher currents may be needed than in an "iron cored" system. Ultimately though, subject to the provision of appropriately rated power supplies, air cored systems can operate with much greater magnetic field strengths than "iron cored" systems, so that, ultimately, much higher accelerations and forces should be possible. Formula for exit velocity of coilgun projectileAn approximate for the exit velocity of a projectile having been accelerated by a single-stage coilgun can be obtained by the equation[17]
m being the mass of the projectile, defined as kg V being the volume of the projectile, defined as m3 μ0 being the vacuum permeability, defined in SI units as 4π × 10−7 V·s/(A·m) χm being the magnetic susceptibility of the projectile, a dimensionless proportionality constant indicating the degree of magnetization in a material in response to applied magnetic fields. This often must be determined experimentally, and tables containing susceptibility values for certain materials may be found in the CRC Handbook of Chemistry and Physics as well as the Wikipedia article for magnetic susceptibility. n being the number of coil turns per unit length of the coil, which can be found by dividing the total turns of the coil by the total length of the coil in meters. and I being the current passing through the coil in amperes. While this approximation is useful for quickly defining the upper limit of velocity in a coilgun system, more accurate and non-linear second order differential equations do exist.[17] The issues with this formula being that it assumes the projectile lies completely within a uniform magnetic field, that the current dies out instantly once the projectile reaches the center of the coil (eliminating the possibility of coil suckback), that all potential energy is transferred into kinetic energy (whereas most would go into frictional forces), and that the wires of the coil are infinitely thin and do not stack on one another, all cumulatively increasing the expected exit velocity.[17] Uses A
M934 mortar round is adapted for experimental coilgun launch with a
conformal armature tail kit, to be fired through a barrel composed of
short solenoidal electromagnets stacked end to end Small coilguns are recreationally made by hobbyists, typically up to several joules to tens of joules projectile energy (the latter comparable to a typical air gun and an order of magnitude less than a firearm) while ranging from under one percent to several percent efficiency.[18] In 2018, a Los Angeles-based company Arcflash Labs offered the first coilgun for sale to the general public, the EMG-01A. It fired 6-gram steel slugs at 45 m/s with a muzzle energy of approximately 5 joules.[19] In 2021, they developed a larger model, the GR-1 Gauss rifle which fired 30-gram steel slugs at up to 75 m/s with a muzzle energy of approximately 85 joules,[20] comparable to a PCP air rifle. In 2022 Northshore Sports Club, an American gun club in Lake Forest, Illinois began distributing the CS/LW21, also referred to as the "E-Shotgun", a compact, 15 joule magazine fed coil gun, manufactured by the China North Industries Group Corp.[21] They project distribution to reach 5000 units per year in the US,[22][23] and the manufacturer has also unveiled plans to supply the Chinese police and military with units for "non-lethal riot control".[24] Much higher efficiency and energy can be obtained with designs of greater expense and sophistication. In 1978, Bondaletov in the USSR achieved record acceleration with a single stage by sending a 2-gram ring to 5000 m/s in 1 cm of length,[25] but the most efficient modern designs tend to involve many stages.[26] It is estimated that greater than 90% efficiency will be required for vastly larger superconducting systems for space launch.[15] An experimental 45-stage, 2.1 m long DARPA coilgun mortar design is 22% efficient, with 1.6 megajoules KE delivered to a round.[27]  A large coilgun concept, a coaxial electromagnetic launcher firing projectiles to orbit Though they face the challenge of competitiveness versus conventional guns (and sometimes railgun alternatives), coilguns are being researched for weaponry.[27] The DARPA Electromagnetic Mortar program is one example, if practical challenges like sufficiently low weight can be achieved. The coilgun would be relatively silent with no smoke giving away its position, though a supersonic projectile would still create a sonic boom. Adjustable, smooth acceleration of the projectile along the barrel length would allow higher velocity, with a predicted range increase of 30% for a 120mm EM mortar over the conventional version of similar length. With no separate propellant charges to load, the researchers envision the firing rate to approximately double.[27][28] In 2006, a 120mm prototype was under construction for evaluation, though a tenuous time for deployment was then estimated to be 5 to 10+ years by Sandia National Laboratories.[27][28] In 2011, development was proposed for an 81mm coilgun mortar to operate with a hybrid-electric version of the future Joint Light Tactical Vehicle.[29][30] Electromagnetic aircraft catapults are planned, including on board future U.S. Gerald R. Ford class aircraft carriers. An experimental induction coilgun version of an Electromagnetic Missile Launcher (EMML) has been tested for launching Tomahawk missiles.[31] A coilgun-based active defense system for tanks is under development at HIT in China.[32] Coilgun potential has been perceived as extending beyond military applications. Few entities could overcome the challenges and corresponding capital investment to fund gigantic coilguns with projectile mass and velocity on the scale of gigajoules of kinetic energy (as opposed to megajoules or less). Such have been proposed as Earth or Moon launchers:
See also
References
External linksWikimedia Commons has media related to Coilguns. https://en.wikipedia.org/wiki/Coilgun https://en.wikipedia.org/wiki/Actinide#Formation_in_nuclear_reactors https://en.wikipedia.org/wiki/Impact_parameter https://en.wikipedia.org/wiki/United_States_Armed_Forces?wprov=srpw1_412 https://en.wikipedia.org/wiki/Denys_Wilkinson_Building https://en.wikipedia.org/wiki/Radiography https://en.wikipedia.org/wiki/3rd_millennium https://en.wikipedia.org/wiki/Seaslug_(missile)#Nuclear_variant_%28not_built%29 https://en.wikipedia.org/wiki/List_of_technology_in_the_Dune_universe https://en.wikipedia.org/wiki/Radioactive_source https://en.wikipedia.org/wiki/Microwave https://en.wikipedia.org/wiki/Precipitation_(chemistry) https://en.wikipedia.org/wiki/Ablative_armor https://en.wikipedia.org/wiki/Fission-fragment_rocket https://en.wikipedia.org/wiki/Radiolysis https://en.wikipedia.org/wiki/LISE%2B%2B#Simulation_programs_used_to_calculate_the_transport_of_ion_beams https://en.wikipedia.org/wiki/Separation_of_isotopes_by_laser_excitation https://en.wikipedia.org/wiki/Resonator https://en.wikipedia.org/wiki/Ion_beam_mixing https://en.wikipedia.org/wiki/KALI_(electron_accelerator) https://en.wikipedia.org/wiki/Lead_shielding https://en.wikipedia.org/wiki/Radar#Beam_path_and_range https://en.wikipedia.org/wiki/Fire-control_radar https://en.wikipedia.org/wiki/Fire-control_radar https://en.wikipedia.org/wiki/Fire-control_radar https://en.wikipedia.org/wiki/Pressure-fed_engine https://en.wikipedia.org/wiki/Flange https://en.wikipedia.org/wiki/Ti-sapphire_laser https://en.wikipedia.org/wiki/View_from_the_Window_at_Le_Gras https://en.wikipedia.org/wiki/Lockheed_Martin_Compact_Fusion_Reactor https://en.wikipedia.org/wiki/Proton#Proton_nuclear_magnetic_resonance_%28NMR%29 https://en.wikipedia.org/wiki/Combustion_tap-off_cycle https://en.wikipedia.org/wiki/Sunbeam_(disambiguation) https://en.wikipedia.org/wiki/List_of_fictional_doomsday_devices https://en.wikipedia.org/wiki/Rocket_engine#Beamed_thermal https://en.wikipedia.org/wiki/Coulomb_explosion https://en.wikipedia.org/wiki/Surface-to-air_missile https://en.wikipedia.org/wiki/Chirped_pulse_amplification https://en.wikipedia.org/wiki/Gas-generator_cycle https://en.wikipedia.org/wiki/Length_measurement https://en.wikipedia.org/wiki/Assignment:_Earth https://en.wikipedia.org/wiki/Gamma_motor_neuron#Effects_of_nuclear_chain_fibers https://en.wikipedia.org/wiki/Gamma_motor_neuron https://en.wikipedia.org/wiki/Earthquake-resistant_structures https://en.wikipedia.org/wiki/Inertial_fusion_power_plant https://en.wikipedia.org/wiki/ISABELLE#Colliding_beam_accelerators https://en.wikipedia.org/wiki/Field-reversed_configuration https://en.wikipedia.org/wiki/Laser_pumping https://en.wikipedia.org/wiki/Wire_chamber https://en.wikipedia.org/wiki/ATLAS_experiment https://en.wikipedia.org/wiki/Helical_railgun https://en.wikipedia.org/wiki/Railgun https://en.wikipedia.org/wiki/Homopolar_motor https://en.wikipedia.org/wiki/Neodymium_magnet https://en.wikipedia.org/wiki/Universal_motor https://en.wikipedia.org/wiki/Stator https://en.wikipedia.org/wiki/Mud_motor https://en.wikipedia.org/wiki/Progressing_cavity_pump https://en.wikipedia.org/wiki/Drilling_fluid https://en.wikipedia.org/wiki/Field_coil https://en.wikipedia.org/wiki/Magnetic_core https://en.wikipedia.org/wiki/Hysteresis https://en.wikipedia.org/wiki/Alternating_current https://en.wikipedia.org/wiki/Coercivity https://en.wikipedia.org/wiki/Magnetic_core#Core_loss https://en.wikipedia.org/wiki/Electromagnetic_induction https://en.wikipedia.org/wiki/Magnetic_domain https://en.wikipedia.org/wiki/Cobalt https://en.wikipedia.org/wiki/Micromagnetics https://en.wikipedia.org/wiki/Saturation_(magnetic) https://en.wikipedia.org/wiki/Magnetometer#Fluxgate_magnetometer https://en.wikipedia.org/wiki/Unexploded_ordnance https://en.wikipedia.org/wiki/Gradiometer https://en.wikipedia.org/wiki/Magnetometer https://en.wikipedia.org/wiki/Magnetic_anomaly Caesium vapour magnetometerThe optically pumped caesium vapour magnetometer is a highly sensitive (300 fT/Hz0.5) and accurate device used in a wide range of applications. It is one of a number of alkali vapours (including rubidium and potassium) that are used in this way.[17] https://en.wikipedia.org/wiki/Magnetometer#Fluxgate_magnetometer A direct current flowing in a solenoid creates a strong magnetic field around a hydrogen-rich fluid (kerosene and decane are popular, and even water can be used), causing some of the protons to align themselves with that field. The current is then interrupted, and as protons realign themselves with the ambient magnetic field, they precess at a frequency that is directly proportional to the magnetic field. This produces a weak rotating magnetic field that is picked up by a (sometimes separate) inductor, amplified electronically, and fed to a digital frequency counter whose output is typically scaled and displayed directly as field strength or output as digital data. https://en.wikipedia.org/wiki/Magnetometer#Fluxgate_magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, one that measures the direction of an ambient magnetic field, in this case, the Earth's magnetic field. Other magnetometers measure the magnetic dipole moment of a magnetic material such as a ferromagnet, for example by recording the effect of this magnetic dipole on the induced current in a coil. The first magnetometer capable of measuring the absolute magnetic intensity at a point in space was invented by Carl Friedrich Gauss in 1833 and notable developments in the 19th century included the Hall effect, which is still widely used. Magnetometers are widely used for measuring the Earth's magnetic field, in geophysical surveys, to detect magnetic anomalies of various types, and to determine the dipole moment of magnetic materials. In an aircraft's attitude and heading reference system, they are commonly used as a heading reference. Magnetometers are also used by the military as a triggering mechanism in magnetic mines to detect submarines. Consequently, some countries, such as the United States, Canada and Australia, classify the more sensitive magnetometers as military technology, and control their distribution. Magnetometers can be used as metal detectors: they can detect only magnetic (ferrous) metals, but can detect such metals at a much greater distance than conventional metal detectors, which rely on conductivity. Magnetometers are capable of detecting large objects, such as cars, at over 10 metres (33 ft), while a conventional metal detector's range is rarely more than 2 metres (6 ft 7 in). In recent years, magnetometers have been miniaturized to the extent that they can be incorporated in integrated circuits at very low cost and are finding increasing use as miniaturized compasses (MEMS magnetic field sensor). IntroductionMagnetic fieldsMagnetic fields are vector quantities characterized by both strength and direction. The strength of a magnetic field is measured in units of tesla in the SI units, and in gauss in the cgs system of units. 10,000 gauss are equal to one tesla.[1] Measurements of the Earth's magnetic field are often quoted in units of nanotesla (nT), also called a gamma.[2] The Earth's magnetic field can vary from 20,000 to 80,000 nT depending on location, fluctuations in the Earth's magnetic field are on the order of 100 nT, and magnetic field variations due to magnetic anomalies can be in the picotesla (pT) range.[3] Gaussmeters and teslameters are magnetometers that measure in units of gauss or tesla, respectively. In some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla (mT) and gaussmeter is used for those measuring greater than 1 mT.[1] Types of magnetometer The Magnetometer experiment for the Juno orbiter for Juno can be seen here on the end of a boom. The spacecraft uses two fluxgate magnetometers. (see also Magnetometer (Juno)) There are two basic types of magnetometer measurement. Vector magnetometers measure the vector components of a magnetic field. Total field magnetometers or scalar magnetometers measure the magnitude of the vector magnetic field.[4] Magnetometers used to study the Earth's magnetic field may express the vector components of the field in terms of declination (the angle between the horizontal component of the field vector and true, or geographic, north) and the inclination (the angle between the field vector and the horizontal surface).[5] Absolute magnetometers measure the absolute magnitude or vector magnetic field, using an internal calibration or known physical constants of the magnetic sensor.[6] Relative magnetometers measure magnitude or vector magnetic field relative to a fixed but uncalibrated baseline. Also called variometers, relative magnetometers are used to measure variations in magnetic field. Magnetometers may also be classified by their situation or intended use. Stationary magnetometers are installed to a fixed position and measurements are taken while the magnetometer is stationary.[4] Portable or mobile magnetometers are meant to be used while in motion and may be manually carried or transported in a moving vehicle. Laboratory magnetometers are used to measure the magnetic field of materials placed within them and are typically stationary. Survey magnetometers are used to measure magnetic fields in geomagnetic surveys; they may be fixed base stations, as in the INTERMAGNET network, or mobile magnetometers used to scan a geographic region. Performance and capabilitiesThe performance and capabilities of magnetometers are described through their technical specifications. Major specifications include[1][3]
Early magnetometers The compass is a simple type of magnetometer.  Coast and Geodetic Survey Magnetometer No. 18. The compass, consisting of a magnetized needle whose orientation changes in response to the ambient magnetic field, is a simple type of magnetometer, one that measures the direction of the field. The oscillation frequency of a magnetized needle is proportional to the square-root of the strength of the ambient magnetic field; so, for example, the oscillation frequency of the needle of a horizontally situated compass is proportional to the square-root of the horizontal intensity of the ambient field.[citation needed] In 1833, Carl Friedrich Gauss, head of the Geomagnetic Observatory in Göttingen, published a paper on measurement of the Earth's magnetic field.[7] It described a new instrument that consisted of a permanent bar magnet suspended horizontally from a gold fibre. The difference in the oscillations when the bar was magnetised and when it was demagnetised allowed Gauss to calculate an absolute value for the strength of the Earth's magnetic field.[8] The gauss, the CGS unit of magnetic flux density was named in his honour, defined as one maxwell per square centimeter; it equals 1×10−4 tesla (the SI unit).[9] Francis Ronalds and Charles Brooke independently invented magnetographs in 1846 that continuously recorded the magnet's movements using photography, thus easing the load on observers.[10] They were quickly utilised by Edward Sabine and others in a global magnetic survey and updated machines were in use well into the 20th century.[11][12] Laboratory magnetometersLaboratory magnetometers measure the magnetization, also known as the magnetic moment of a sample material. Unlike survey magnetometers, laboratory magnetometers require the sample to be placed inside the magnetometer, and often the temperature, magnetic field, and other parameters of the sample can be controlled. A sample's magnetization, is primarily dependent on the ordering of unpaired electrons within its atoms, with smaller contributions from nuclear magnetic moments, Larmor diamagnetism, among others. Ordering of magnetic moments are primarily classified as diamagnetic, paramagnetic, ferromagnetic, or antiferromagnetic (although the zoology of magnetic ordering also includes ferrimagnetic, helimagnetic, toroidal, spin glass, etc.). Measuring the magnetization as a function of temperature and magnetic field can give clues as to the type of magnetic ordering, as well as any phase transitions between different types of magnetic orders that occur at critical temperatures or magnetic fields. This type of magnetometry measurement is very important to understand the magnetic properties of materials in physics, chemistry, geophysics and geology, as well as sometimes biology. SQUID (superconducting quantum interference device)SQUIDs are a type of magnetometer used both as survey and as laboratory magnetometers. SQUID magnetometry is an extremely sensitive absolute magnetometry technique. However SQUIDs are noise sensitive, making them impractical as laboratory magnetometers in high DC magnetic fields, and in pulsed magnets. Commercial SQUID magnetometers are available for temperatures between 300 mK and 400 K, and magnetic fields up to 7 tesla. Inductive pickup coilsInductive pickup coils (also referred as inductive sensor) measure the magnetic dipole moment of a material by detecting the current induced in a coil due to the changing magnetic moment of the sample. The sample's magnetization can be changed by applying a small ac magnetic field (or a rapidly changing dc field), as occurs in capacitor-driven pulsed magnets. These measurements require differentiating between the magnetic field produced by the sample and that from the external applied field. Often a special arrangement of cancellation coils is used. For example, half of the pickup coil is wound in one direction, and the other half in the other direction, and the sample is placed in only one half. The external uniform magnetic field is detected by both halves of the coil, and since they are counter-wound, the external magnetic field produces no net signal. VSM (vibrating-sample magnetometer)Vibrating-sample magnetometers (VSMs) detect the dipole moment of a sample by mechanically vibrating the sample inside of an inductive pickup coil or inside of a SQUID coil. Induced current or changing flux in the coil is measured. The vibration is typically created by a motor or a piezoelectric actuator. Typically the VSM technique is about an order of magnitude less sensitive than SQUID magnetometry. VSMs can be combined with SQUIDs to create a system that is more sensitive than either one alone. Heat due to the sample vibration can limit the base temperature of a VSM, typically to 2 Kelvin. VSM is also impractical for measuring a fragile sample that is sensitive to rapid acceleration. Pulsed-field extraction magnetometryPulsed-field extraction magnetometry is another method making use of pickup coils to measure magnetization. Unlike VSMs where the sample is physically vibrated, in pulsed-field extraction magnetometry, the sample is secured and the external magnetic field is changed rapidly, for example in a capacitor-driven magnet. One of multiple techniques must then be used to cancel out the external field from the field produced by the sample. These include counterwound coils that cancel the external uniform field and background measurements with the sample removed from the coil. Torque magnetometryMagnetic torque magnetometry can be even more sensitive than SQUID magnetometry. However, magnetic torque magnetometry doesn't measure magnetism directly as all the previously mentioned methods do. Magnetic torque magnetometry instead measures the torque τ acting on a sample's magnetic moment μ as a result of a uniform magnetic field B, τ = μ × B. A torque is thus a measure of the sample's magnetic or shape anisotropy. In some cases the sample's magnetization can be extracted from the measured torque. In other cases, the magnetic torque measurement is used to detect magnetic phase transitions or quantum oscillations. The most common way to measure magnetic torque is to mount the sample on a cantilever and measure the displacement via capacitance measurement between the cantilever and nearby fixed object, or by measuring the piezoelectricity of the cantilever, or by optical interferometry off the surface of the cantilever. Faraday force magnetometryFaraday force magnetometry uses the fact that a spatial magnetic field gradient produces force that acts on a magnetized object, F = (M⋅∇)B. In Faraday force magnetometry the force on the sample can be measured by a scale (hanging the sample from a sensitive balance), or by detecting the displacement against a spring. Commonly a capacitive load cell or cantilever is used because of its sensitivity, size, and lack of mechanical parts. Faraday force magnetometry is approximately one order of magnitude less sensitive than a SQUID. The biggest drawback to Faraday force magnetometry is that it requires some means of not only producing a magnetic field, but also producing a magnetic field gradient. While this can be accomplished by using a set of special pole faces, a much better result can be achieved by using set of gradient coils. A major advantage to Faraday force magnetometry is that it is small and reasonably tolerant to noise, and thus can be implemented in a wide range of environments, including a dilution refrigerator. Faraday force magnetometry can also be complicated by the presence of torque (see previous technique). This can be circumvented by varying the gradient field independently of the applied DC field so the torque and the Faraday force contribution can be separated, and/or by designing a Faraday force magnetometer that prevents the sample from being rotated. Optical magnetometryOptical magnetometry makes use of various optical techniques to measure magnetization. One such technique, Kerr magnetometry makes use of the magneto-optic Kerr effect, or MOKE. In this technique, incident light is directed at the sample's surface. Light interacts with a magnetized surface nonlinearly so the reflected light has an elliptical polarization, which is then measured by a detector. Another method of optical magnetometry is Faraday rotation magnetometry. Faraday rotation magnetometry utilizes nonlinear magneto-optical rotation to measure a sample's magnetization. In this method a Faraday modulating thin film is applied to the sample to be measured and a series of images are taken with a camera that senses the polarization of the reflected light. To reduce noise, multiple pictures are then averaged together. One advantage to this method is that it allows mapping of the magnetic characteristics over the surface of a sample. This can be especially useful when studying such things as the Meissner effect on superconductors. Microfabricated optically pumped magnetometers (µOPMs) can be used to detect the origin of brain seizures more precisely and generate less heat than currently available superconducting quantum interference devices, better known as SQUIDs.[13] The device works by using polarized light to control the spin of rubidium atoms which can be used to measure and monitor the magnetic field.[14] https://en.wikipedia.org/wiki/Magnetometer#Fluxgate_magnetometer https://en.wikipedia.org/wiki/Micromagnetics https://en.wikipedia.org/wiki/Gyromagnetic_ratio https://en.wikipedia.org/wiki/Magnetocrystalline_anisotropy https://en.wikipedia.org/wiki/Continuum_mechanics https://en.wikipedia.org/wiki/Magnetic_nanoparticles https://en.wikipedia.org/wiki/Centrifugal_governor
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