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## PowerPedia:Heat engine

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In There was an error working with the wiki: Code[263] and Thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot "source" and a cold "sink".

#### Introduction

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!History of Heat Engines

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Pre Eighteenth century

c200BC:Temple fire anvil of Cestisibus used to magically open the temple doors. http://www.history.rochester.edu/steam/thurston/1878/Chapter1.html

c200BC:There was an error working with the wiki: Code[264]. Demonstrates rotary motion produced by the reaction from jets of steam.

1120:Gerbert, a professor in the schools at Rheims designed and built an organ blown by air escaping from a vessel in which it was compressed " by heated water.

c1500: There was an error working with the wiki: Code[265] builds the Architonnerre a steam powered cannon

1665:There was an error working with the wiki: Code[266], the Second Marquis of Worcester builds a working steam fountain.

1680:Huyghens publishes a design for a piston engine powered by gunpowder but it is never built.

1690:There was an error working with the wiki: Code[267] - produces design for the first piston steam engine.

1698: There was an error working with the wiki: Code[268] builds a pistonless steam-powered water There was an error working with the wiki: Code[269] for pumping water out of mines.

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Eighteenth century

1707:There was an error working with the wiki: Code[270] - produces design for his second piston steam engine in conjunction with There was an error working with the wiki: Code[271].

1712:There was an error working with the wiki: Code[259] for pumping water out of mines

1769:There was an error working with the wiki: Code[272] patents his first improved Steam engine

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Nineteenth century

1816:There was an error working with the wiki: Code[273] invented his hot air Stirling engine

1859:There was an error working with the wiki: Code[274] developed the first internal combustion engine, a single-cylinder, two-stroke engine with electric ignition of illumination gas (not gasoline).

1877: There was an error working with the wiki: Code[275] patents a four-stroke Internal combustion engine (There was an error working with the wiki: Code[1])

1892:Rudolf Diesel patents the Diesel engine (There was an error working with the wiki: Code[2])

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Twentieth century

1929:There was an error working with the wiki: Code[260] (There was an error working with the wiki: Code[3])

1937:There was an error working with the wiki: Code[276] builds a Gas turbine

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Heat engines relates to devices where the prime mover or engine is one in which a combustible material is "burned" within an inclosed space or chamber and the heat energy thus developed converted into work by permitting the resulting products of combustion to act upon and through mechanical powers. Heat engines have been known since antiquity but were only made into useful devices at the time of the industrial revolution in the eighteenth century. They continue to be developed today. In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot "source" and a cold "sink". Heat is transferred to the sink from the source, and in this process some of the heat is converted into work.

The engine in question includes suitable mechanism whose functions are continually and automatically carried out. Such engine are designed to communicate power to some machine or device exterior to itself. The space or combustion chamber is ordinarily the interior of the working cylinder of the engine. The products of combustion acting immediately upon a reciprocating, rotating, or oscillating piston moving within a chamber in which combustion takes place or in an extension thereof. Some types of heat engines, however, besides operating as mentioned, have a transfer valve operated by and in unison with the valve which is located between the combustion chamber and the elements upon and through which the products of combustion act to thereby control the product flow. In such cases, the transfer valve is operated to establish communication between the combustion chamber and the working cylinder at the instant of ignition or prior thereto, so that the piston is driven by burning products of combustion.

Heat is transferred in a heat engine to the sink from the source, and in this process some of the heat is converted into work by exploiting the properties of a working substance (usually a gas or liquid). The working fluid is ordinarily such as results from combustion alone but in some of the engines in this class a small quantity of water is supplied to the engine, generally by injecting it directly into the interior of the combustion-chamber during or after the combustion of the combustible material but in all engines using water the amount used is comparatively small, so that the resulting steam is necessarily in a superheated condition. Heat enegines also includes separate parts of engines coming within the above definition and also subordinate elements designed for use with such engines, and incapable of use in the manner contemplated with other devices or in other relations. Any given structure adapted for use as an internal-combustion engine could generally with slight modification be used with steam or other media, and often as an air, gas, or water pump, a hydraulic motor, a meter.

In general terms, the larger the difference in temperature between the hot source and the cold sink, the larger is the potential efficiency of the cycle. On Earth, the cold side of any heat engine is limited to close to the ambient temperature of the environment, or not much lower than 300 Kelvin, so most efforts to improve the thermodynamic efficiencies of various heat engines focus on increasing the temperature of the source, within material limits. Examples of everyday heat engines include: the steam engine, the diesel engine, and the gasoline (petrol) engine in an automobile. A common toy that is also a heat engine is a drinking bird. All of these familiar heat engines are powered by the expansion of heated gases. The general surroundings are the heat sink, providing relatively cool gases which, when heated, expand rapidly to drive the mechanical motion of the engine

The efficiency of various heat engines proposed or used today ranges from 3 percent (97 percent waste heat) for the OTEC ocean power proposal through 25 percent for most automotive engines, to 35 percent for a supercritical coal plant, to about 60 percent for a steam-cooled combined cycle gas turbine. All of these processes gain their efficiency (or lack thereof) due to the temperature drop across them. OTEC uses the temperature difference of ocean water on the surface and ocean water from the depths, a small difference of perhaps 25 degrees celsius, and so the efficiency must be low. The combined cycle gas turbines use natural-gas fired burners to heat air to near 1530 degrees celsius, a difference of a large 1500 degrees, and so the efficiency can be large when the steam-cooling cycle is added in.

#### Heat engine types and operation

##### Phase change cycles

In these cycles and engines, the working fluids are gases and liquids. The engine converts the working fluid from a gas to a liquid. The There was an error working with the wiki: Code[277] is a thermodynamic cycle, especially applicable to the classical Steam engines. Like other thermodynamic cycles, the maximum efficiency of the Rankine cycle is given by calculating the maximum efficiency of the Carnot cycle. It is named after William John Macquorn Rankine, a Scottish polymath. The There was an error working with the wiki: Code[278] is more efficient than Rankine cycle.

The There was an error working with the wiki: Code[279] cycle is ued bby "Drinking birds" toys. They are a thermodynamically powered toy heat engine. They are also known as happy birds, dippy birds, tippy birds, sippy birds, sipping birds, dunking birds, and tipping birds. The drinking bird is basically a heat engine that exploits a temperature differential to convert heat energy to kinetic energy and perform mechanical work. Like all heat engines, the drinking bird works through a thermodynamic cycle. The initial state of the system is a bird with a wet head oriented vertically with an initial oscillation on its pivot.

The cycle operates as follows:

#The water evaporates from the head (Maxwell-Boltzmann distribution)

#Evaporation lowers the temperature of the glass head (heat of vaporization)

#The temperature drop causes some of the dichloromethane vapour in the head to condense

#The lower temperature and condensation together cause the pressure to drop in the head (ideal gas law)

#The pressure differential between the head and base causes the liquid to be pushed up from the base.

#As liquid flows into the head, the bird becomes top heavy and tips over during its oscillations.

#When the bird tips over, the bottom end of the neck tube rises above the surface of the liquid.

#A bubble of vapour rises up the tube through this gap, displacing liquid as it goes

#Liquid flows back to the bottom bulb, and vapour pressure equalizes between the top and bottom bulbs

#The weight of the liquid in the bottom bulb restores the bird to its vertical position

If a glass of water is placed so that the beak dips into it on its descent, the bird will continue to absorb water and the cycle will continue as long as there is enough water in the glass to keep the head wet. However, the bird will continue to dip even without a source of water, as long as the head is wet, or as long as a temperature differential is maintained between the head and body. This differential can be generated without evaporative cooling in the head -- for instance, a heat source directed at the bottom bulb will create a pressure differential between top and bottom that will drive the engine. The ultimate source of energy is heat in the surrounding environment -- the toy is not a perpetual motion machine.

There was an error working with the wiki: Code[280] (or frost heave) occurs when soil expands and contracts due to freezing and thawing. This process can damage plant roots through breaking or desiccation, cause cracks in pavement, and damage the foundations of buildings, even below the frost line. Moist, fine-grained soil at certain temperatures is most susceptible to frost heaving. The water changing from ice to liquid and back again can lift rock up to 60m. Originally, frost heaving was thought to occur due simply to the freezing of water in soil. However, the vertical displacement of soil in frost heaving can be significantly greater than the expansion that occurs when ice freezes. In the 1960s, frost heaving was demonstrated in soil saturated in benzene and nitrobenzene, which contract when they freeze. The current understanding is that certain soil particles have a high affinity for liquid water. As the liquid water around them freezes, these soils draw in liquid water from the unfrozen soils around them. If the air temperature is below freezing but relatively stable, the heat of fusion from the water that freezes can cause the temperature gradient in the soil to remain constant. The soil at the point where freezing is occurring continues to draw in liquid water from the soils below it, which then freezes and builds u

##### Gas only cycles

The There was an error working with the wiki: Code[281] is a particular thermodynamic cycle, modeled on the Carnot heat engine, studied by Nicolas Léonard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s. Every thermodynamic system exists in a particular state. A thermodynamic cycle occurs when a system is taken through a series of different states, and finally returned to its initial state. In the process of going through this cycle, the system may perform work on its surroundings, thereby acting as a heat engine. A heat engine acts by transferring energy from a warm region to a cool region of space and, in the process, converting some of that energy to mechanical work. The cycle may also be reversed. The system may be worked upon by an external force, and in the process, it can transfer thermal energy from a cooler system to a warmer one, thereby acting as a refrigerator rather than a heat engine. The Carnot cycle is a special type of thermodynamic cycle. It is special because it is the most efficient cycle possible for converting a given amount of thermal energy into work or, conversely, for using a given amount of work for refrigeration purposes.

A Carnot heat engine is a hypothetical engine that operates on the reversible Carnot cycle. The basic model for this engine was developed by Nicolas Léonard Sadi Carnot in the 1824. The Carnot engine model was graphically expanded upon by Benoit Paul Émile Clapeyron in 1834 and mathematically elaborated upon by Rudolf Clausius in the 1850s and 60s from which the concept of entropy emerged. Every thermodynamic system exists in a particular state. A thermodynamic cycle occurs when a system is taken through a series of different states, and finally returned to its initial state. In the process of going through this cycle, the system may perform work on its surroundings, thereby acting as a heat engine. A heat engine acts by transferring energy from a warm region to a cool region of space and, in the process, converting some of that energy to mechanical work. The cycle may also be reversed. The system may be worked upon by an external force, and in the process, it can transfer thermal energy from a cooler system to a warmer one, thereby acting as a refrigerator rather than a heat engine. In the adjacent diagram, from the original 1824 paper by Sadi Carnot entitled On the Motive Power of Fire, we are told to “imagine two bodies A and B, kept each at a constant temperature, that of A being higher than that of B. These two bodies, to which we can give or from which we can remove the heat without causing their temperatures to vary, exercise the functions of two unlimited reservoirs of caloric. We shall call the first the furnace and the second the refrigerator". Carnot then explains how we can obtain motive power, i.e. “work", by carrying a certain quantity of heat from the body A to the body B.

The "There was an error working with the wiki: Code[282]" is a constant pressure cycle named after George Brayton (1830-1892), the American engineer who developed it in Gas turbines. In 1872 Brayton filed a patent for his "Ready Motor" unlike the Otto or Diesel cycles Brayton's engine used a separate compressor and expansion cylinder. Today the Brayton cycle is a cyclic process generally associated with the gas turbine. Like other internal combustion power cycles it is an open system, though for thermodynamic analysis it is a convenient fiction to assume that the exhaust gases are reused in the intake, enabling analysis as a closed system. It is also sometimes known as the There was an error working with the wiki: Code[283].

The There was an error working with the wiki: Code[284] is named after inventor John Ericsson. The Ericsson cycle is very similar to what we now call the "Brayton Cycle". The main difference is that the all Ericsson engines are externally heated and usually have a recuperator or regenerator between the compressor and the expander. The Ericsson cycle is often compared to the Stirling Cycle because of its external combustion capabilities, use of a regenerator and the high potential efficiency. Barber was the first to propose a similar engine in 1791 but the Barber engine lacked a regenerator/ recuperator. Ericsson invented and patented his first engine in 1833 (number 6409/1833 British). This was 18 years before Joule and 43 years before Brayton. Brayton engines were for the most part an internal combustion version of the Ericsson Cycle which was a considerable improvement to external heating. The "Brayton Cycle" is now known as the gas turbine cycle, which differs from the original "Brayton Cycle" in the use of a turbine compressor and expander. The gas turbine cycle is used for all modern gas turbine and turbojet engines. Ericsson eventually abandoned the open cycle in favor of the traditional closed Stirling cycle. At one point an Ericsson cycle engine was used to power a 2000 ton ship, The Caloric Ship Ericsson and the engine ran flawlessly for 73 hours. The combination engine produced about 300 horsepower. It had a combination of 4 2-piston engines the larger, the expansion piston/cylinder, being 4.267 meters or 14 feet in diameter--perhaps the largest piston diameter of any engine ever built. Rumor has it that tables were placed on top of those pistons and dinner was served and eaten, while the engine was running at full power. At 6.5 Rpm the pressure was limited to 8 psi. Ericsson also introduced the twin-screw propeller for ship design, in the USS Princeton.

The Stirling engine is a heat engine of the external combustion piston engine type whose heat-exchange process allows for near-ideal efficiency in conversion of heat into mechanical movement by following the Carnot cycle as closely as is practically possible with given materials. Its invention is credited to the Scottish clergyman Rev. Robert Stirling in 1816 who made significant improvements to earlier designs and took out the first patent. He was later assisted in its development by his engineer brother James Stirling.

The Internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. This exothermic reaction of a fuel with an oxidizer creates gases of high temperature and pressure, which are permitted to expand. The defining feature of an internal combustion engine is that useful work is performed by the expanding hot gases acting directly to cause movement, for example by acting on pistons, rotors, or even by pressing on and moving the entire engine itself. This contrasts with external combustion engines such as steam engines which use the combustion process to heat a separate working fluid, typically water or steam, which then in turn does work, for example by pressing on a steam actuated piston. The term Internal Combustion Engine (ICE) is almost always used to refer specifically to reciprocating engines, Wankel engines and similar designs in which combustion is intermittent. However, continuous combustion engines, such as Jet engines, most rockets and many gas turbines are also very definitely internal combustion engines.

The There was an error working with the wiki: Code[285] (or There was an error working with the wiki: Code[286]) of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today (cars and trucks, generators, etc). The Thermodynamics cycles used in internal combustion reciprocating engines are the Otto Cycle (the ideal cycle for spark-ignition engines) and the Diesel Cycle (the ideal cycle for compression-ignition engines). The Otto Cycle consists of Adiabatic compression,heat addition at constant volume,Adiabatic expansion and rejection of heat at constant volume. It was conceptualized by the French engineer, Alphonse Beau de Rochas in 1862, and independently, by the German engineer Nicolaus Otto in 1876. The four-stroke cycle is more fuel efficient and clean burning than the two-stroke cycle, but requires considerably more moving parts and manufacturing expertise. Moreover, it is more easily manufactured in multi-cylinder configurations than the two-stroke, making it especially useful in high-output applications such as cars. The later-invented Wankel engine has four similar phases but is a rotary combustion engine rather than the much more usual, reciprocating engine of the four-stroke cycle.

The Otto cycle is characterized by four strokes, or straight movements alternately, back and forth, of a piston inside a cylinder:

#intake (induction) stroke

#compression stroke

#power (combustion) stroke

#exhaust stroke

The cycle begins at top dead center, when the piston is at its uppermost point. On the first downward stroke (intake) of the piston, a mixture of fuel and air is drawn into the cylinder through the intake (inlet) port. The intake (inlet) valve (or valves) then close(s), and the following upward stroke (compression) compresses the fuel-air mixture. The air-fuel mixture is then ignited, usually by a spark plug for a gasoline or Otto cycle engine, or by the heat and pressure of compression for a Diesel cycle of compression ignition engine, at approximately the top of the compression stroke. The resulting expansion of burning gases then forces the piston downward for the third stroke (power), and the fourth and final upward stroke (exhaust) evacuates the spent exhaust gases from the cylinder past the then-open exhaust valve or valves, through the exhaust port.

The Diesel cycle is the combustion process of a type of internal combustion engine, in which the burning of the fuel is triggered by the heat generated in first compressing air in the piston cavity, into which is then injected the fuel - as opposed to it being ignited by a spark plug, as combustion is in the Otto cycle (four-stroke/petrol) engine. Diesel engines (Heat engines utilizing the Diesel cycle) are used in automobiles, power generation, diesel-electric locomotives, and submarines.

The There was an error working with the wiki: Code[287] engine is a type of Internal combustion engine invented by James Atkinson in 1882. The Atkinson cycle is designed to provide efficiency at the expense of power. The Atkinson cycle allows the intake, compression, power, and exhaust strokes of the four-stroke cycle to occur in a single turn of the crankshaft. Owing to the linkage, the expansion ratio is greater than the compression ratio, leading to greater efficiency than with engines using the alternative Otto cycle. The Atkinson cycle may also refer to a four stroke engine in which the intake valve is held open longer than normal to allow a reverse flow of intake air into the intake manifold. This reduces the effective compression ratio and, when combined with an increased stroke and/or reduced combustion chamber volume, allows the expansion ratio to exceed the compression ratio while retaining a normal compression pressure. This is desirable for improved fuel economy because the compression ratio in a spark ignition engine is limited by the octane rating of the fuel used. A high expansion ratio delivers a longer power stroke, allowing more expansion of the combustion gases and reducing the amount of heat wasted in the exhaust. This makes for a more efficient engine.

The There was an error working with the wiki: Code[288] is an idealised thermodynamic cycle for the pulse jet engine. An ideal gas undergoes:

#constant volume heating

#isobaric compression to the volume at the start of the cycle.

The expansion process is isentropic and hence involves no heat interaction. Energy is absorbed as heat during the constant volume process and rejected as heat during the constant pressure process. A pulse jet engine (or pulsejet) is a very simple form of internal combustion engine wherein the combustion occurs in pulses and the propulsive effort is a jet, this is, a reaction to the rearward flow of hot gases. A typical pulsejet comprises an air intake fitted with a one-way valve, a combustion chamber, and an acoustically resonant exhaust pipe. The valving is accomplished though the use of reed valves or, in a valveless pulse jet engine, through aerodynamics. Fuel in the form of a gas or liquid aerosol is either mixed with the air in the intake or injected into the combustion chamber. Once the engine is running it requires only an input of fuel, but it usually requires forced air and an ignition method for the fuel-air mix. Once running, the engine is self-sustaining.

The There was an error working with the wiki: Code[289] is a combustion process used in a type of four-stroke internal combustion engine. The Miller cycle was patented by Ralph Miller (engineer), an American engineer, in the 1940s. This type of engine was first used in ships and stationary power-generating plants, but was adapted by Mazda for their KJ-ZEM V6, used in the Millenia sedan. More recently, Subaru has combined a Miller cycle flat-4 with a hybrid driveline for their "Turbo Parallel Hybrid" car, known as the Subaru B5-TPH. A traditional Otto cycle engine uses four "strokes", of which two can be considered "high power" – the compression stroke (high power consumption) and power stroke (high power production). Much of the internal power loss of an engine is due to the energy needed to compress the charge during the compression stroke, so systems that reduce this power consumption can lead to greater efficiency.

In the Miller cycle, the intake valve is left open longer than it would be in an Otto cycle engine. In effect, the compression stroke is two discrete cycles: the initial portion when the intake valve is open and final portion when the intake valve is closed. This two-stage intake stroke creates the so called "fifth" cycle that the Miller cycle introduces. As the piston initially moves upwards in what is traditionally the compression stroke, the charge is being pushed back out the still-open valve. Typically this loss of charge air would result in a loss of power. However, in the Miller cycle, the piston is over-fed with charge air from a supercharger, so pushing some of the charge air back out into the intake manifold is entirely planned. The supercharger typically will need to be of the positive displacement type due its ability to produce boost at relatively low engine speeds. Otherwise, low-rpm torque will suffer. A key aspect of the Miller cycle is that the compression stroke actually starts only after the piston has pushed out this "extra" charge and the intake valve closes. This happens at around 20% to 30% into the compression stroke. In other words, the actual compression occurs in the latter 70% to 80% of the compression stroke. The piston gets the same resulting compression as it would in a standard Otto cycle engine for 70% of the work.

The Miller cycle results in an advantage as long as the supercharger can compress the charge using less energy than the piston would use to do the same work. Over the entire compression range required by an engine, the supercharger is used to generate low levels of compression, where it is most efficient. Then, the piston is used to generate the remaining higher levels compression, operating in the range where it is more efficient than a supercharger. Thus the Miller cycle uses the supercharger for the portion of the compression where it is best, and the piston for the portion where it is best. In total, this reduces in the power needed to run the engine by 10% to 15%. To this end, successful production engines using this cycle have typically used variable valve timing to effectively switch off the Miller cycle in regions of operation where it does not offer an advantage. In a typical spark ignition engine, the Miller cycle yields an additional benefit. The intake air is first compressed by the supercharger and then cooled by an intercooler. This lower intake charge temperature, combined with the lower compression of the intake stroke, yields a lower final charge temperature than would be obtained by simply increasing the compression of the piston. This allows ignition timing to be altered to beyond what is normally allowed before the onset of detonation, thus increasing the overall efficiency still further.

Efficiency is increased by raising the compression ratio. In a typical gasoline engine, the compression ratio is limited due to self-ignition (detonation) of the compressed, and therefore hot, air/fuel mixture. Due to the reduced compression stroke of a Miller cycle engine, a higher overall compression ratio (supercharger compression plus piston compression) is possible, and therefore a Miller cycle engine has a better efficiency. It should be noted that the benefits of utilizing positive displacement superchargers do not come without a cost. 15% to 20% of the power generated by a supercharged engine is usually required to do the work of driving the supercharger, which compresses the intake charge (also known as boost). A similar delayed-valve closing method is used in some modern versions of Atkinson cycle engines, but without the supercharging. These engines are generally found on hybrid electric vehicles, where efficiency is the goal, and the power lost compared to the Miller cycle is made up through the use of electric motors.

##### Electron cycles

There was an error working with the wiki: Code[290] is the conversion from temperature differentials to electricity or vice versa. It is accomplished in one of several ways:

# The Peltier-Seebeck effect

# Thermionic emission

# Indirectly through magnetohydrodynamics

The There was an error working with the wiki: Code[291], or thermoelectric effect, is the direct conversion of heat differentials to electric voltage and vice versa. Related effects are the Thomson effect and Joule heating. The Peltier–Seebeck and Thomson effects are reversible (in fact, the Peltier and Seebeck effects are reversals of one another) Joule heating cannot be reversible under the laws of thermodynamics. The Seebeck effect is the conversion of heat differences directly into electricity. This effect was first discovered, accidentally, by the Estonian physicist Thomas Johann Seebeck in 1821, who found that a voltage existed between two ends of a metal bar when a temperature gradient \nabla T existed in the bar. He also discovered that a compass needle would be deflected when a closed loop was formed of two metals with a temperature difference between the junctions. This is because the metals respond differently to the heat difference, which creates a current loop, which produces a magnetic field. A voltage, the thermoelectric EMF, is created in the presence of a temperature difference between two different metals or semiconductors. This usually causes a continuous current to flow in the conductors. The voltage created is on the order of several microvolts per degree of difference. The Peltier effect is the reverse of the Seebeck effect a creation of a heat difference from an electric voltage. It occurs when a current is passed through two dissimilar metals or semiconductors (n-type and p-type) that are connected to each other at two junctions (Peltier junctions). The current drives a transfer of heat from one junction to the other: one junction cools off while the other heats up as a result, the effect is often used for thermoelectric cooling. This effect was observed in 1834 by Jean Peltier, 13 years after Seebeck's initial discovery.

The conducting material is not limited to solids with electrons as charge carriers. Such effects can be observed in conductors where the carriers are ions, or in semiconductors where the carriers are holes or electrons. It is the principle behind heat engines, heat pumps, thermocouples, thermal diodes, and solid-state refrigerators, etc. It can be used to electrically measure temperature, or to generate power from a heat source. The heat from radioactive decay has been used to electrically power several space probes, in the form of radioisotope thermoelectric generators. Thermoelectric power sometimes refers to this direct conversion, but usually just refers to a power plant which converts heat into electricity, through the use of steam turbines or similar device. Thermoelectricity was widely used in the remote parts of the Soviet Union from the 1920s to power radios. The equipment comprised some bi-metal rods, one end of which could be inserted into the fireplace to get hot with the other end left out in the cold. Another way of achieving the same function is a Clockwork radio.

There was an error working with the wiki: Code[292] (archaically known as the There was an error working with the wiki: Code[293]) is the flow of electrons from a metal or metal oxide surface, caused by thermal vibrational energy overcoming the electrostatic forces holding electrons to the surface. The effect increases dramatically with increasing temperature (1000–3000 K), but is always present at temperatures above absolute zero. The science dealing with this phenomenon is thermionics. The charged particles are called thermions. There was an error working with the wiki: Code[294] is similar to thermionic emission cooling in that fast moving electrons carry heat across a gap but cannot return due to a voltage difference. The problem with using thermal electrons to carry heat is the fact that, due to the high work function of metals (the only practical emitters), the lowest cooling temperate is around 600C - clearly not useful except in the most unusual applications. Thermotunnel cooling avoids this problem by making the gap narrow enough that electrons can tunnel across the gap, carrying the heat with them. The problem with this approach has been getting two surfaces near enough that they can tunnel over a large area, yet not touch at any point (which would short the device out preventing it from doing any useful cooling). Cool Chips[1] is a startup trying to optimise a new process for production of these very close surfaces in preparation for selling practical devices. Their approach is to make a thin (5nm) spacer layer in a special sandwich of materials. Once the chip is assembled, the spacer layer is chemically removed and tiny piezoelectric actuators maintain the precise spacing required. At this point no devices are available commercially as the technology is still undergoing refinement.

##### Photon cycles

There was an error working with the wiki: Code[295] (also called light sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion using large membrane mirrors. Radiation pressure is small and decreases by the square of the distance from the sun, but unlike rockets, solar sails require no fuel. Although the thrust is small, it continues as long as the sun shines and the sail exists. The spacecraft deploys a large membrane mirror which reflects light from the Sun or some other source. The radiation pressure on the mirror provides a minuscule amount of thrust by reflecting photons. Tilting the reflective sail at an angle from the Sun produces thrust at an angle that bisects the angle between the Sun and the spacecraft. In most designs, steering would be done with auxiliary vanes, acting as small solar sails to change the attitude of the large solar sail (see the vanes on the illustration). The vanes would be adjusted by electric motors. Sails orbit, and therefore do not need to hover or move directly toward or away from the sun. Almost all missions would use the sail to change orbit, rather than thrusting directly away from a planet or the sun. The sail is rotated slowly as the sail orbits around a planet so the thrust is in the direction of the orbital movement to move to a higher orbit or against it to move to a lower orbit. When an orbit is far enough away from a planet, the sail then begins similar maneuvers in orbit around the sun.

The best sort of missions for a solar sail involves a dive near the sun, where the light is intense, and sail efficiencies are high. For this reason, most sails are designed to tolerate much higher temperatures than one might expect. Going close to the Sun may be done for different mission aims: for exploring the solar poles from a short distance, for observing the Sun and its near environment from a non-Keplerian circular orbit the plane of which may be shifted some solar radii, for flying-by the Sun such that the sail gets a very high speed. An unsuspected feature, until the first half of the Nineties, of the solar sail propulsion is to allow a sailcraft to escape the solar system with a cruise speed higher (or even much higher) than a spacecraft powered by a nuclear electric rocket system. The spacecraft mass to sail area ratio does not need to achieve ultra-low values, even though the sail should be an advanced all-metal sail. This flight mode is also known as the fast solar sailing. Proven mathematically (like many other astronautical items well in advance of their actual launches), such sailing mode has been considered by NASA/Marshall as one of the options for a future precursor interstellar probe (NASA/CR 2002-211730, the chapter IV) exploring the near interstellar space beyond the heliosphere. Most theoretical studies of interstellar missions with a solar sail plan to push the sail with a very large laser. The thrust vector would therefore be away from the Sun and toward the target

##### Cycles used for refrigeration

A There was an error working with the wiki: Code[296] is a There was an error working with the wiki: Code[297]: a heat engine in reverse. Work is used to create a heat differential. The [Carnot refrigeration]] uses the Carnot cycle in reverse. The There was an error working with the wiki: Code[298] is a refrigerator that utilizes a heat source to provide the energy needed to drive the cooling system rather than being dependent on electricity to run a compressor. These refrigerators are popular where electricity is unreliable, costly, or unavailable, or where surplus heat is available, e.g., from turbine exhausts or industrial processes. An absorption refrigerator is similar to a regular compressor refrigerator in that the refrigeration takes place by evaporating a liquid with a very low (sub-zero) boiling point. In both cases, when a liquid evaporates or boils, it takes some heat away with it, and can continue to do so either until the liquid is all boiled, or until everything has become so cold that the sub-zero boiling point has been reached. The difference between the two is how the gas is changed back into a liquid so that it may be used again. A regular refrigerator uses a compressor to increase the pressure on the gas, forcing it to become a liquid again. An absorption refrigerator uses a different method that requires no moving parts and is powered only by heat.

##### Heat engine processes

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! Cycle/Process !! Compression !! Heat Addition !! Expansion !! Heat Rejection

|-

! Carnot

|-

! Otto (Petrol)

|-

! Diesel

|-

! Brayton (Jet)

|-

! Stirling

|isothermal || isometric || isothermal || isometric

|-

! Ericsson

|isothermal || isobaric || isothermal || isobaric

|}

Each process is either There was an error working with the wiki: Code[261] (at constant volume), or There was an error working with the wiki: Code[299] (no heat is added or removed from the working fluid).

#### Efficiency

The efficiency of a heat engine relates how much useful power is output for a given amount of heat energy input. From the laws of Thermodynamics:

: dW \ = \ dQ_c \ - \ (-dQ_h)

where

: dW = -PdV is the work extracted from the engine. (It is negative since work is done by the engine.)

: dQ_h = T_hdS_h is the heat energy taken from the high temperature system .(It is negative since heat is extracted from the source, hence (-dQ_h) is positive.)

: dQ_c = T_cdS_c is the heat energy delivered to the cold temperature system. (It is positive since heat is added to the sink.)

In other words, a heat engine absorbs heat energy from the high temperature heat source, converting part of it to useful work and delivering the rest to the cold temperature heat sink. In general, the efficiency of a given heat transfer process (whether it be a refrigerator, a heat pump or an engine) is defined informally by the ratio of "what you get" to "what you put in." In the case of an engine, one desires to extract work and puts in a heat transfer.

:\eta = \frac{-dW}{-dQ_h} = \frac{-dQ_h - dQ_c}{-dQ_h} = 1 - \frac{dQ_c}{-dQ_h}

The theoretical maximum efficiency of any heat engine depends only on the temperatures it operates between. This efficiency is usually derived using an ideal imaginary heat engine such as the There was an error working with the wiki: Code[262] processes, the change in Entropy of the cold reservoir is the negative of that of the hot reservoir (i.e., dS_c = -dS_h), keeping the overall change of entropy zero. Thus:

:\eta_{max} = 1 - \frac{T_cdS_c}{-T_hdS_h} \equiv 1 - \frac{T_c}{T_h}

where T_h is the There was an error working with the wiki: Code[300] of the hot source and T_c that of the cold sink, usually measured in There was an error working with the wiki: Code[301]s. Note that dS_c is positive while dS_h is negative in any reversible work-extracting process, entropy is overall not increased, but rather is moved from a hot (high-entropy) system to a cold (low-entropy one), decreasing the entropy of the heat source and increasing that of the heat sink. The reasoning behind this being the maximal efficiency goes as follows. It is first assumed that if a more efficient heat engine than a Carnot engine is possible, then it could be driven in reverse as a heat pump. Mathematical analysis can be used to show that this assumed combination would result in a net decrease in Entropy. Since, by the Second law of thermodynamics, this is forbidden, the Carnot efficiency is a theoretical upper bound on the efficiency of any process. Empirically, no engine has ever been shown to run at a greater efficiency than a Carnot cycle heat engine.

#### Other performance criteria

One problem with the ideal Carnot efficiency as a criterion of heat engine performance is the fact that by its nature, any maximally-efficient Carnot cycle must operate at an infinitesimal temperature gradient. This is due to the fact that any transfer of heat between two bodies at differing temperatures is irreversible, and therefore the Carnot efficiency expression only applies in the infinitesimal limit. The major problem with that is that the object of most heat engines is to output some sort of power, and infinitesimal power is usually not what is being sought.

A much more accurate measure of heat engine efficiency is given by the endoreversible process, which is identical to the Carnot cycle except in that the two processes of heat transfer are not treated as reversible. As derived in Callen (1985), the efficiency for such a process is given by:

:\eta = 1 - \sqrt{\frac{T_c}{T_h}}

The accuracy of this model can be seen in the following table:

{|width="100%"

|+Efficiencies of Power Plants

|-

! Power Plant !! T_c (°C) !! T_h (°C) !! \eta (Carnot) !! \eta (Endoreversible) !! \eta (Observed)

|-

! West Thurrock (United Kingdom) Fossil fuel power plant

| 25 || 565 || 0.64 || 0.40 || 0.36

|-

! CANDU reactor (Canada) nuclear power plant

| 25 || 300 || 0.48 || 0.28 || 0.30

|-

! Larderello (Italy) geothermal power plant

| 80 || 250 || 0.32 || 0.175 || 0.16

|}

As shown, the endoreversible efficiency much more closely models the observed data.

#### Engine Enhancements

Engineers have studied the various heat engine cycles extensively in an effort to improve the amount of usable work they could extract from a given power source. The Carnot Cycle limit cannot be reached with any gas-based cycle, but engineers have worked out at least two ways to possibly go around that limit, and one way to get better efficiency without bending any rules.

Increase the temperature difference in the heat engine:The simplest way to do this is to increase the hot side temperature, and is the approach used in modern combined-cycle gas turbines. Unfortunately, NOx production and material limits (melting the turbine blades) place a hard limit to how hot you can make a workable heat engine. Modern gas turbines are about as hot as they can become and still maintain acceptable NOx pollution levels. Another way of increasing efficiency is to lower the output temperature. Once new method of doing so is to use mixed chemical working fluids, and then exploit the changing behavior of the mixtures. One of the most famous is the so-called Kalina Cycle, which uses a 70/30 mix of ammonia and water as its working fluid. This mixture allows the cycle to generate useful power at considerably lower temperatures than most other processes.

Exploit the physical properties of the working fluid:The most common such exploit is the use of water above the so-called critical point, or so-called supercritical steam. The behavior of fluids above their critical point changes radically, and with materials such as water and carbon dioxide it is possible to exploit those changes in behavior to extract greater thermodynamic efficiency from the heat engine, even if it is using a fairly conventional Brayton or Rankine cycle. A newer and very promising material for such applications is CO2. SO2 and xenon have also been considered for such applications, although SO2 is a little toxic for most.

Exploit the chemical properties of the working fluid:A fairly new and novel exploit is to use exotic working fluids with advantageous chemical properties. One such is nitrogen dioxide(NO2), a toxic component of smog, which has a natural dimer as di-nitrogen tetraoxide(N2O4). At low temperature, the N2O4 is compressed and then heated. The increasing temperature causes each N2O4 to break apart into two NO2 molecules. This lowers the molecular weight of the working fluid, which drastically increases the efficiency of the cycle. Once the NO2 has expanded through the turbine, it is cooled by the heat sink, which causes it to re-combine into N2O4. This is then fed back to the compressor for another cycle. Such species as aluminum bromide (Al2Br6), NOCl, and Ga2I6 have all been investigated for such uses. To date, their drawbacks have not warranted their use, despite the efficiency gains that can be realized.

#### Patents

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There was an error working with the wiki: Code[4] Apparatus and method for controlling an internal combustion engine

There was an error working with the wiki: Code[5] Intake-air quantity control apparatus for internal combustion engine with variable valve timing system

There was an error working with the wiki: Code[6] Unthrottled engine operation with a heated air cycle

There was an error working with the wiki: Code[7] Intake control device of internal combustion engine

There was an error working with the wiki: Code[8] Otto-cycle engine

There was an error working with the wiki: Code[9] Rotary valve and system for duration and phase control

There was an error working with the wiki: Code[10] Manifold tuning

There was an error working with the wiki: Code[11] Intake system for internal combustion engines

There was an error working with the wiki: Code[12] Intake system for internal combustion engines

There was an error working with the wiki: Code[13] Internal combustion engine

There was an error working with the wiki: Code[14] Non-throttling control apparatus for spark ignition internal combustion engines

There was an error working with the wiki: Code[15] Acceleration controlling device for an automobile vehicle

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There was an error working with the wiki: Code[18] 123/405 137/48 137/49 137/82

There was an error working with the wiki: Code[19] 137/514.5 123/405 137/479 137/517 138/46

There was an error working with the wiki: Code[20] 74/404.5 123/363 123/405 137/53 73/530

There was an error working with the wiki: Code[21] 123/67 123/182.1 123/405 123/65VB 123/90.16

There was an error working with the wiki: Code[22] 261/50.1 123/405 137/100 261/69.2 261/DIG.2 261/DIG.52 261/DIG.53

There was an error working with the wiki: Code[23] 123/23

There was an error working with the wiki: Code[24] 123/23 123/71V

There was an error working with the wiki: Code[25] 123/59.1 123/179.16 123/405 123/65V 123/65W

There was an error working with the wiki: Code[26] 123/23 123/143B 123/61R

There was an error working with the wiki: Code[27] 60/39.091 110/104R 123/23 60/39.464

There was an error working with the wiki: Code[28] 123/23 406/122 406/156

There was an error working with the wiki: Code[29] 123/23 123/55.7 123/67

There was an error working with the wiki: Code[30] 60/39.281 123/23 60/39.22 60/39.464 60/39.81

There was an error working with the wiki: Code[31] 123/23

There was an error working with the wiki: Code[32] 123/23 123/74C

There was an error working with the wiki: Code[33] 123/23

There was an error working with the wiki: Code[34] 123/23 123/65VB

There was an error working with the wiki: Code[35] 123/23 406/130 406/86

There was an error working with the wiki: Code[36] 123/23

There was an error working with the wiki: Code[37] 60/39.13 123/23 60/39.22 60/39.81 60/914

There was an error working with the wiki: Code[38] 123/58.3 123/405 123/62 123/65VB 123/74AA 123/74AC

There was an error working with the wiki: Code[39] 123/23

There was an error working with the wiki: Code[40] 23/405 123/DIG.4

There was an error working with the wiki: Code[41] 123/23 123/193.4 123/41.31 123/51B 123/65VA 123/69R

There was an error working with the wiki: Code[42] 123/23 123/54.4

There was an error working with the wiki: Code[43] 123/403 123/405

There was an error working with the wiki: Code[44] 123/23 110/262 123/590

There was an error working with the wiki: Code[45] 123/23 356/439

There was an error working with the wiki: Code[46] 123/58.5 123/405 123/69V 123/71V 123/73CA 123/90.18

There was an error working with the wiki: Code[47] 123/303 123/23 123/306 123/65W

There was an error working with the wiki: Code[48] 123/50R 123/23 123/26

There was an error working with the wiki: Code[49] 60/39.35 123/23 60/250 60/39.464 60/39.47

There was an error working with the wiki: Code[50] 123/405

There was an error working with the wiki: Code[51] 123/405 123/73V

There was an error working with the wiki: Code[52] 123/23 123/27R 123/270 123/279 123/47R 123/67 123/69V 123/71R 123/71V 123/73C 123/73CA 123/73FA 239/88 92/212 92/217

There was an error working with the wiki: Code[53] 123/19 123/23

There was an error working with the wiki: Code[54] 123/405

There was an error working with the wiki: Code[55] 74/404.5 123/403 123/405 73/494

There was an error working with the wiki: Code[56] 123/405 123/346 137/54

There was an error working with the wiki: Code[57] 60/630 123/405 123/65R 123/65V 123/65VB

There was an error working with the wiki: Code[58] 123/405

There was an error working with the wiki: Code[59] 123/527 123/405 123/79R 137/607 137/614.2

There was an error working with the wiki: Code[60] 123/41E 123/74B 60/39.76

There was an error working with the wiki: Code[61] 60/39.15 415/153.1 415/52.1 415/53.2 415/60 415/61 60/39.76 60/724

There was an error working with the wiki: Code[62] 60/39.281 48/74 60/39.3 60/39.55 60/39.76

There was an error working with the wiki: Code[63] 123/27R 123/61R 123/61V

There was an error working with the wiki: Code[64] 123/23 123/25B 123/557

There was an error working with the wiki: Code[65] 123/405 123/188.8 123/90.1

There was an error working with the wiki: Code[66] 60/39.091 60/39.25 60/39.44 60/39.76

There was an error working with the wiki: Code[67] 123/73AB 123/26 123/405 123/58.4 123/65VB 123/69V 123/90.18 123/90.6

There was an error working with the wiki: Code[68] 123/63 123/41.82R 123/82

There was an error working with the wiki: Code[69] 123/144 123/145R

There was an error working with the wiki: Code[70] 123/533 123/27R

There was an error working with the wiki: Code[71] 60/39.44 415/147 415/186 60/39.76 60/731

There was an error working with the wiki: Code[72] 123/405

There was an error working with the wiki: Code[73] 123/73AB 123/65VD 60/39.76

There was an error working with the wiki: Code[74] 123/405 123/430

There was an error working with the wiki: Code[75] 123/346 123/405 137/53 73/544

There was an error working with the wiki: Code[76] 123/55.4 123/195R 123/82 123/84 123/DIG.6

There was an error working with the wiki: Code[77] 123/405 123/188.2 123/58.2 123/90.6

There was an error working with the wiki: Code[78] 123/51AA 123/41.65 123/51A 123/51B 123/51BA 123/82 123/90.23

There was an error working with the wiki: Code[79] 60/39.827 60/39.76 60/793

There was an error working with the wiki: Code[80] 123/27R 123/294

There was an error working with the wiki: Code[81] 123/27R 123/294 123/61R 123/65VB 123/74C

There was an error working with the wiki: Code[82] 123/27R 123/1R 123/585 44/457 60/39.48

There was an error working with the wiki: Code[83] 123/27R 123/288 123/533

There was an error working with the wiki: Code[84] 123/441 123/82 123/86

There was an error working with the wiki: Code[85] 123/27R 123/193.1 123/54.2 123/55.5 123/55.7 123/71R 123/76 60/39.55

There was an error working with the wiki: Code[86] 60/514 123/27R 91/333 91/351 92/144

There was an error working with the wiki: Code[87] 123/41R 123/27R

There was an error working with the wiki: Code[88] 123/73A 123/405 123/48C 123/65A

There was an error working with the wiki: Code[89] 60/39.27 60/39.76 60/805

There was an error working with the wiki: Code[90] 123/249 114/21.1 123/210 123/23 123/24R 418/144 418/191 60/914 89/1.16

There was an error working with the wiki: Code[91] 60/39.55 237/12.1 60/39.3 60/39.53 60/39.76

There was an error working with the wiki: Code[92] 60/39.22 180/302 60/39.15 60/39.76 60/39.821 60/727

There was an error working with the wiki: Code[93] 123/27R 123/193.6 123/195P 123/47R 123/668 92/170.1

There was an error working with the wiki: Code[94] 123/27R 123/585 123/593

There was an error working with the wiki: Code[95] 123/405 123/190.2 123/190.5

There was an error working with the wiki: Code[96] 123/405 123/346 123/85

There was an error working with the wiki: Code[97] 123/82 123/182.1

There was an error working with the wiki: Code[98] 60/39.091 60/39.08 60/39.41 60/39.76

There was an error working with the wiki: Code[99] 60/39.55 123/23 60/39.461 60/39.63

There was an error working with the wiki: Code[100] 60/39.15 415/150 415/153.1 415/154.1 60/39.44 60/39.76 60/39.78

There was an error working with the wiki: Code[101] 123/405

There was an error working with the wiki: Code[102] 123/58.2 123/188.2 123/405 261/DIG.25

There was an error working with the wiki: Code[103] 137/54 123/403 123/405

There was an error working with the wiki: Code[104] 123/48A 123/192.1 123/197.1 123/198R 123/405 123/48R 123/78A 123/90.18 92/60

There was an error working with the wiki: Code[105] 123/52.3 123/332 123/344 123/405 123/82

There was an error working with the wiki: Code[106] 91/333 123/2 123/363 123/41.02 123/82 91/332

There was an error working with the wiki: Code[107] 123/532 123/144

There was an error working with the wiki: Code[108] 123/405

There was an error working with the wiki: Code[109] 123/23

There was an error working with the wiki: Code[110] 123/61V 123/27R 123/65VB 123/68 123/69V

There was an error working with the wiki: Code[111] 123/405

There was an error working with the wiki: Code[112] 123/405

There was an error working with the wiki: Code[113] 123/255 123/27R 123/557

There was an error working with the wiki: Code[114] 123/69V 123/27R 123/61V 123/65VB

There was an error working with the wiki: Code[115] 123/182.1 123/82

There was an error working with the wiki: Code[116] 123/405

There was an error working with the wiki: Code[117] 123/82

There was an error working with the wiki: Code[118] 123/405 123/188.1 123/347

There was an error working with the wiki: Code[119] 123/344 123/82 123/90.14

There was an error working with the wiki: Code[120] 123/405 123/90.32 123/90.61

There was an error working with the wiki: Code[121] 123/27R

There was an error working with the wiki: Code[122] 60/731 60/39.76 60/805

There was an error working with the wiki: Code[123] 123/405 123/346

There was an error working with the wiki: Code[124] 123/46R 60/39.76 60/910

There was an error working with the wiki: Code[125] 123/80BB 123/152 123/179.19 123/196CP 123/405 123/41.4 123/41.78 123/73CA 137/625.47 184/6.24 184/6.5 251/183

There was an error working with the wiki: Code[126] 123/1R 123/23

There was an error working with the wiki: Code[127] 123/54.4 123/195A 123/332 123/405 123/65V 123/71R

There was an error working with the wiki: Code[128] 123/347 123/161 123/163 123/188.2 123/82 123/90.44 123/90.65

There was an error working with the wiki: Code[129] 60/624 123/23

There was an error working with the wiki: Code[130] 123/56.4 123/143R 123/144 123/78E 74/582 74/60

There was an error working with the wiki: Code[131] 417/73 123/23 123/46R 60/39.52

There was an error working with the wiki: Code[132] 123/27R 123/540 123/70V

There was an error working with the wiki: Code[133] 123/19 123/23 123/48R 123/90.48 60/39.76

There was an error working with the wiki: Code[134] 123/19 123/23 123/48R 123/90.48 60/39.76

There was an error working with the wiki: Code[135] 60/39.76

There was an error working with the wiki: Code[136] 123/348 123/66 123/78AA 123/82

There was an error working with the wiki: Code[137] 123/79R 123/150 123/405 123/90.17

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| align="left" valign="top"|

There was an error working with the wiki: Code[138] 123/1R 123/27GE 123/27R 123/65VB 261/DIG.45

There was an error working with the wiki: Code[139] 123/405 123/188.4 251/325 261/65

There was an error working with the wiki: Code[140] 123/546 123/82

There was an error working with the wiki: Code[141] 123/525 123/157 123/82 123/90.44

There was an error working with the wiki: Code[142] 123/364 123/27R 123/338 417/294 73/534

There was an error working with the wiki: Code[143] 123/78C 60/39.76

There was an error working with the wiki: Code[144] 123/332 123/405

There was an error working with the wiki: Code[145] 60/621 123/405 123/41.69 123/51A 123/51BB 123/51BC 92/69B 92/69R

There was an error working with the wiki: Code[146] 123/79R 123/145R 123/332 123/344 123/405 73/534

There was an error working with the wiki: Code[147] 123/332 123/152 123/347 123/405

There was an error working with the wiki: Code[148] 123/68 123/1R 123/23 123/55.7 123/69V

There was an error working with the wiki: Code[149] 123/378 123/332 123/346 123/405 123/59.7 123/70R

There was an error working with the wiki: Code[150] 74/3 123/153 123/82

There was an error working with the wiki: Code[151] 123/1R 123/160 123/23 123/294 123/41.57 123/41.67 123/61R 123/61V 123/68 261/119.1

There was an error working with the wiki: Code[152] 123/78B 123/160 123/163 123/197.1 123/345 123/363 123/82

There was an error working with the wiki: Code[153] 123/274 123/158 123/163 123/405 123/83

There was an error working with the wiki: Code[154] 123/2 123/144 123/25Q 123/41R 123/61R 123/65VB 123/70V 277/500 48/41

There was an error working with the wiki: Code[155] 123/450 123/179.7 123/82

There was an error working with the wiki: Code[156] 123/27R 123/23 60/39.76

There was an error working with the wiki: Code[157] 123/73V 123/405 123/65VB

There was an error working with the wiki: Code[158] 123/82 123/158 123/163 123/332 123/348

There was an error working with the wiki: Code[159] 123/528 123/429 123/82

There was an error working with the wiki: Code[160] 123/405 123/348 74/3

There was an error working with the wiki: Code[161] 123/23 123/51BB 123/66

There was an error working with the wiki: Code[162] 123/46SC 123/27R 123/39 92/137

There was an error working with the wiki: Code[163] 123/332 123/145R 123/182.1 123/376 123/82

There was an error working with the wiki: Code[164] 123/378 123/156 123/41.77 123/70V 123/82 123/90.39

There was an error working with the wiki: Code[165] 123/335 123/158 123/345 123/347 123/82

There was an error working with the wiki: Code[166] 180/229 123/144 123/195HC 123/197.1 123/53.1 180/205

There was an error working with the wiki: Code[167] 123/82 123/152 123/161 123/90.21

There was an error working with the wiki: Code[168] 123/592 123/82 48/189.5

There was an error working with the wiki: Code[169] 123/161 123/143R 123/182.1 123/184.1 123/346 123/82

There was an error working with the wiki: Code[170] 60/39.48 48/180.1 60/39.76

There was an error working with the wiki: Code[171] 60/315 123/144

There was an error working with the wiki: Code[172] 123/292 123/274 123/82 261/40

There was an error working with the wiki: Code[173] 123/160 123/163 123/164 123/169R 123/332 123/405 123/82

There was an error working with the wiki: Code[174] 123/405

There was an error working with the wiki: Code[175] 123/332 123/346 123/65WA 123/82

There was an error working with the wiki: Code[176] 123/82 123/348

There was an error working with the wiki: Code[177] 123/27R 123/1R 123/25C 123/25Q 123/294 123/58.4 123/65VB 60/39.76

There was an error working with the wiki: Code[178] 123/62 123/146 123/405 123/47R 123/65VD 123/65WA 123/69V

There was an error working with the wiki: Code[179] 123/82 123/348

There was an error working with the wiki: Code[180] 123/332 123/405

There was an error working with the wiki: Code[181] 123/82 123/145R 123/344 123/90.39 251/142 251/263 251/277

There was an error working with the wiki: Code[182] 123/41R 123/144 123/189 123/193.1 123/346 123/41.78 123/78B 92/84

There was an error working with the wiki: Code[183] 123/82 123/151 123/169R

There was an error working with the wiki: Code[184] 123/23 123/195HC 123/197.1 123/198R 123/3 123/41.35 123/41.4 123/41.72 123/41.77 123/72

There was an error working with the wiki: Code[185] 123/405 123/348 73/494

There was an error working with the wiki: Code[186] 123/332 123/146 123/196R 123/346 123/82

There was an error working with the wiki: Code[187] 60/39.27 417/218 60/39.47 60/39.56 60/39.76 60/914

There was an error working with the wiki: Code[188] 60/712 123/144

There was an error working with the wiki: Code[189] 137/614.12 123/82

There was an error working with the wiki: Code[190] 99/348 123/144 141/146 99/356

There was an error working with the wiki: Code[191] 123/23 123/346 123/348 123/53.1 123/72 60/508

There was an error working with the wiki: Code[192] 123/82 123/144 123/179.7

There was an error working with the wiki: Code[193] 123/22 123/145R 123/23 123/41.48 123/52.5 123/657 123/70V 123/77

There was an error working with the wiki: Code[194] 123/252 123/146 123/82 60/39.76

There was an error working with the wiki: Code[195] 123/144

There was an error working with the wiki: Code[196] 123/84 123/144 123/325 123/41.72

There was an error working with the wiki: Code[197] 123/161 123/196R 123/325 123/405 123/90.16 184/18 92/159

There was an error working with the wiki: Code[198] 123/225 123/162 123/210 123/346 123/405 418/263 418/43

There was an error working with the wiki: Code[199] 123/332 123/376 123/82

There was an error working with the wiki: Code[200] 123/298 123/82 261/18.3 261/44.5 261/50.2

There was an error working with the wiki: Code[201] 60/804 123/450 60/39.76 60/39.81

There was an error working with the wiki: Code[202] 123/78F 123/144 123/195HC 123/197.1 123/53.1 123/548

There was an error working with the wiki: Code[203] 123/81B 123/144

There was an error working with the wiki: Code[204] 123/144

There was an error working with the wiki: Code[205] 123/77 123/144

There was an error working with the wiki: Code[206]123/144

There was an error working with the wiki: Code[207] 123/144 123/188.2 123/306 123/65VB 123/90.65

There was an error working with the wiki: Code[208] 23/144

There was an error working with the wiki: Code[209] 123/405

There was an error working with the wiki: Code[210] 123/65VB 123/144 123/69V

There was an error working with the wiki: Code[211] 123/79C 123/144

There was an error working with the wiki: Code[212] 123/144

There was an error working with the wiki: Code[213] 123/144 123/182.1

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#### External articles and references

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Heat Engine

Webarchive backup: Refrigeration Cycle Citat: "...The refrigeration cycle is basically the Rankine cycle run in reverse..."

Red Rock Energy Solar Heliostats: Heat Engine Projects Citat: "...Choosing a Heat Engine..."

Overview of heat engine types

The rotary piston array machine

There was an error working with the wiki: Code[1], Wikipedia: The Free Encyclopedia. Wikimedia Foundation.

THE GROWTH OF THE STEAM-ENGINE. ROBERT H. THURSTON, A. M., C. E., NEW YORK: D. APPLETON AND COMPANY, 1878.

Kroemer, Herbert Kittle, Charles (1980). Thermal Physics, 2nd ed., W. H. Freeman Company. ISBN 0716710889.

Callen, Herbert B. (1985). Thermodynamics and an Introduction to Thermostatistics, 2nd ed., John Wiley & Sons, Inc.. ISBN 0471862568.