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| | It is very common to have a dental emergency -- a fractured tooth, an abscess, or severe pain when chewing. Over-the-counter pain medication is just masking the problem. Seeing an emergency dentist is critical to getting the source of the problem diagnosed and corrected as soon as possible.<br><br><br><br>Here are some common dental emergencies:<br>Toothache: The most common dental emergency. This generally means a badly decayed tooth. As the pain affects the tooth's nerve, treatment involves gently removing any debris lodged in the cavity being careful not to poke deep as this will cause severe pain if the nerve is touched. Next rinse vigorously with warm water. Then soak a small piece of cotton in oil of cloves and insert it in the cavity. This will give temporary relief until a dentist can be reached.<br><br>At times the pain may have a more obscure location such as decay under an old filling. As this can be only corrected by a dentist there are two things you can do to help the pain. Administer a pain pill (aspirin or some other analgesic) internally or dissolve a tablet in a half glass (4 oz) of warm water holding it in the mouth for several minutes before spitting it out. DO NOT PLACE A WHOLE TABLET OR ANY PART OF IT IN THE TOOTH OR AGAINST THE SOFT GUM TISSUE AS IT WILL RESULT IN A NASTY BURN.<br><br>Swollen Jaw: This may be caused by several conditions the most probable being an abscessed tooth. In any case the treatment should be to reduce pain and swelling. An ice pack held on the outside of the jaw, (ten minutes on and ten minutes off) will take care of both. If this does not control the pain, an analgesic tablet can be given every four hours.<br><br>Other Oral Injuries: Broken teeth, cut lips, bitten tongue or lips if severe means a trip to a dentist as soon as possible. In the mean time rinse the mouth with warm water and place cold compression the face opposite the injury. If there is a lot of bleeding, apply direct pressure to the bleeding area. If bleeding does not stop get patient to the emergency room of a hospital as stitches may be necessary.<br><br>Prolonged Bleeding Following Extraction: Place a gauze pad or better still a moistened tea bag over the socket and have the patient bite down gently on it for 30 to 45 minutes. The tannic acid in the tea seeps into the tissues and often helps stop the bleeding. If bleeding continues after two hours, call the dentist or take patient to the emergency room of the nearest hospital.<br><br>Broken Jaw: If you suspect the patient's jaw is broken, bring the upper and lower teeth together. Put a necktie, handkerchief or towel under the chin, tying it over the head to immobilize the jaw until you can get the patient to a dentist or the emergency room of a hospital.<br><br>Painful Erupting Tooth: In young children teething pain can come from a loose baby tooth or from an erupting permanent tooth. Some relief can be given by crushing a little ice and wrapping it in gauze or a clean piece of cloth and putting it directly on the tooth or gum tissue where it hurts. The numbing effect of the cold, along with an appropriate dose of aspirin, usually provides temporary relief.<br><br>In young adults, an erupting 3rd molar (Wisdom tooth), especially if it is impacted, can cause the jaw to swell and be quite painful. Often the gum around the tooth will show signs of infection. Temporary relief can be had by giving aspirin or some other painkiller and by dissolving an aspirin in half a glass of warm water and holding this solution in the mouth over the sore gum. AGAIN DO NOT PLACE A TABLET DIRECTLY OVER THE GUM OR CHEEK OR USE THE ASPIRIN SOLUTION ANY STRONGER THAN RECOMMENDED TO PREVENT BURNING THE TISSUE. The swelling of the jaw can be reduced by using an ice pack on the outside of the face at intervals of ten minutes on and ten minutes off.<br><br>When you have virtually any concerns concerning wherever in addition to the way to make use of [http://www.youtube.com/watch?v=90z1mmiwNS8 Best Dentists in DC], you'll be able to email us with the web-site. |
| {{Thermodynamics|cTopic=[[Thermodynamic system|Systems]]}}
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| {{See also|Thermodynamic cycle}}
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| In [[thermodynamics]], a '''heat engine''' is a system that performs the conversion of heat or [[thermal energy]] to [[mechanical work]].<ref>''Fundamentals of Classical Thermodynamics'', 3rd ed. p. 159, (1985) by G.J. Van Wylen and R.E. Sonntag: "A heat engine may be defined as a device that operates in a thermodynamic cycle and does a certain amount of net positive work as a result of heat transfer from a high-temperature body and to a low-temperature body. Often the term heat engine is used in a broader sense to include all devices that produce work, either through heat transfer or combustion, even though the device does not operate in a thermodynamic cycle. The internal-combustion engine and the gas turbine are examples of such devices, and calling these heat engines is an acceptable use of the term."</ref><ref>''Mechanical efficiency of heat engines'', p. 1 (2007) by James R. Senf: "Heat engines are made to provide mechanical energy from thermal energy."</ref> It does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat "source" generates thermal energy that brings the working substance to the high temperature state. The working substance generates work in the "[[Thermodynamic system|working body]]" of the engine while [[Heat transfer|transferring heat]] to the colder "[[Heat sink|sink]]" until it reaches a low temperature state. During this process some of the thermal energy is converted into [[energy|work]] by exploiting the properties of the working substance. The working substance can be any system with a non-zero [[heat capacity]], but it usually is a gas or liquid.
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| In general an engine converts energy to mechanical [[Work (physics)|work]]. Heat engines distinguish themselves from other types of engines by the fact that their efficiency is fundamentally limited by [[Carnot's theorem (thermodynamics)|Carnot's theorem]].<ref>''Thermal physics: entropy and free energies'', by Joon Chang Lee (2002), Appendix A, p. 183: "A heat engine absorbs energy from a heat source and then converts it into work for us.","When the engine absorbs heat energy, the absorbed heat energy comes with entropy." (heat energy <math>\Delta Q=T \Delta S</math>), "When the engine performs work, on the other hand, no entropy leaves the engine. This is problematic. We would like the engine to repeat the process again and again to provide us with a steady work source. ... to do so, the working substance inside the engine must return to its initial thermodynamic condition after a cycle, which requires to remove the remaining entropy. The engine can do this only in one way. It must let part of the absorbed heat energy leave without converting it into work. Therefore the engine cannot convert all of the input energy into work!"</ref> Although this efficiency limitation can be a drawback, an advantage of heat engines is that most forms of energy can be easily converted to heat by processes like [[exothermic reaction]]s (such as combustion), [[Absorption (electromagnetic radiation)|absorption]] of light or energetic particles, [[friction]], [[dissipation]] and [[Electrical resistance|resistance]]. Since the heat source that supplies thermal energy to the engine can thus be powered by virtually any kind of energy, heat engines are very versatile and have a wide range of applicability.
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| Heat engines are often confused with the cycles they attempt to mimic. Typically when describing the physical device the term 'engine' is used. When describing the model the term 'cycle' is used.
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| ==Overview==
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| [[Image:heat engine.png|300px|thumb|right|Figure 1: Heat engine diagram]]
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| In [[thermodynamics]], heat engines are often modeled using a standard engineering model such as the [[Otto cycle]]. The theoretical model can be refined and augmented with actual data from an operating engine, using tools such as an [[indicator diagram]]. Since very few actual implementations of heat engines exactly match their underlying thermodynamic cycles, one could say that a thermodynamic cycle is an ideal case of a mechanical engine. In any case, fully understanding an engine and its efficiency requires gaining a good understanding of the (possibly simplified or idealized) theoretical model, the practical nuances of an actual mechanical engine, and the discrepancies between the two.
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| In general terms, the larger the difference in temperature between the hot source and the cold sink, the larger is the potential [[thermal efficiency]] of the cycle. On Earth, the cold side of any heat engine is limited to being 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. The maximum theoretical efficiency of a heat engine (which no engine ever attains) is equal to the temperature difference between the hot and cold ends divided by the temperature at the hot end, all expressed in [[absolute temperature]] or kelvins.
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| The efficiency of various heat engines proposed or used today ranges from 3 percent <ref>[http://www.scribd.com/doc/147785416/Experimental-Investigations-on-a-Standing-Wave-Thermoacoustic-Engine#fullscreen M. Emam, Experimental Investigations on a Standing-Wave Thermoacoustic Engine, M.Sc. Thesis, Cairo University, Egypt (2013)].</ref> (97 percent waste heat using low quality heat) for the [[Ocean thermal energy conversion|OTEC]] ocean power proposal through 25 percent for most automotive engines {{Citation needed|date=March 2011}}, to 45 percent for a [[supercritical coal-fired power station]], to about 60 percent for a steam-cooled [[combined cycle]] [[gas turbine]].<ref>[http://memagazine.asme.org/Web/Efficiency_by_Numbers.cfm "Efficiency by the Numbers"] by Lee S. Langston</ref>
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| All of these processes gain their efficiency (or lack thereof) due to the temperature drop across them.
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| ===Power===
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| Heat engines can be characterized by their [[power density|specific power]], which is typically given in kilowatts per litre of [[engine displacement]] (in the U.S. also [[horsepower]] per cubic inch). The result offers an approximation of the peak power output of an engine. This is not to be confused with [[fuel efficiency]], since high efficiency often requires a lean fuel-air ratio, and thus lower power density. A modern high-performance car engine makes in excess of 75 kW/l (1.65 hp/in³).
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| ==Everyday examples==
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| Examples of everyday heat engines include the [[steam engine]](for example in trains), the [[diesel engine]], and the [[internal combustion engine|gasoline (petrol) engine]] in an automobile.
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| A common toy that is also a heat engine is a [[drinking bird]]. Also the [[stirling engine]] is a heat engine.
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| All of these familiar heat engines are powered by the expansion of heated gases.
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| The general surroundings are the heat sink, providing relatively cool gases which, when heated, expand rapidly to drive the mechanical motion of the engine.
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| ==Examples of heat engines==
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| It is important to note that although some cycles have a typical combustion location (internal or external), they often can be implemented with the other. For example, [[John Ericsson]] developed an external heated engine running on a cycle very much like the earlier [[Diesel cycle]]. In addition, externally heated engines can often be implemented in open or closed cycles.
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| ===Phase-change cycles===
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| In these cycles and engines, the working fluids are gases and liquids. The engine converts the working fluid from a gas to a liquid, from liquid to gas, or both, generating work from the fluid expansion or compression. | |
| * [[Rankine cycle]] (classical [[steam engine]])
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| * [[Regenerative cycle]] ([[steam engine]] more efficient than [[Rankine cycle]])
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| * [[Organic Rankine cycle]] (Coolant changing phase in temperature ranges of ice and hot liquid water)
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| * Vapor to liquid cycle ([[Drinking bird]], [[Injector]], [[Minto wheel]])
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| * Liquid to solid cycle ([[Frost heaving]] — water changing from ice to liquid and back again can lift rock up to 60 cm.)
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| * Solid to gas cycle ([[Dry ice cannon]] — Dry ice sublimes to gas.)
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| ===Gas-only cycles===
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| In these cycles and engines the working fluid is always a gas (i.e., there is no phase change):
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| * [[Carnot cycle]] ([[Carnot heat engine]])
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| * [[Ericsson cycle]] ([[Caloric Ship John Ericsson]])
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| * [[Stirling cycle]] ([[Stirling engine]], [[Thermoacoustic refrigeration|thermoacoustic]] devices)
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| * [[Internal combustion engine]] (ICE):
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| ** [[Otto cycle]] (e.g. [[Gasoline/Petrol engine]], [[high-speed diesel engine]])
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| ** [[Diesel cycle]] (e.g. low-speed [[diesel engine]])
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| ** [[Atkinson cycle]] ([[Atkinson engine]])
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| ** [[Brayton cycle]] or [[Joule cycle]] originally [[Ericsson cycle]] ([[gas turbine]])
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| ** [[Lenoir cycle]] (e.g., [[pulse jet engine]])
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| ** [[Miller cycle]]
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| ===Liquid only cycle===
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| In these cycles and engines the working fluid are always like liquid:
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| * [[Stirling cycle]] ([[Malone engine]])
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| * Heat Regenerative Cyclone<ref>{{cite web|url=http://www.cyclonepower.com/works.html |title=Cyclone Power Technologies Website |publisher=Cyclonepower.com |date= |accessdate=2012-03-22}}</ref>
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| ===Electron cycles===
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| * [[Johnson thermoelectric energy converter]]
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| * Thermoelectric ([[Peltier–Seebeck effect]])
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| * [[Thermionic emission]]
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| * [[Thermotunnel cooling]]
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| ===Magnetic cycles===
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| * [[Thermo-magnetic motor]] (Tesla)
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| ===Cycles used for refrigeration===
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| {{main|refrigeration}}
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| A domestic [[refrigerator]] is an example of a [[heat pump]]: a heat engine in reverse. Work is used to create a heat differential. Many cycles can run in reverse to move heat from the cold side to the hot side, making the cold side cooler and the hot side hotter. Internal combustion engine versions of these cycles are, by their nature, not reversible.
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| Refrigeration cycles include:
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| * [[Vapor-compression refrigeration]]
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| * [[Stirling engine#Stirling cryocoolers|Stirling cryocoolers]]
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| * [[Gas-absorption refrigerator]]
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| * [[Air cycle machine]]
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| * [[Vuilleumier refrigeration]]
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| * [[Magnetic refrigeration]]
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| ===Evaporative heat engines===
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| The [[Barton evaporation engine]] is a heat engine based on a cycle producing power and cooled moist air from the evaporation of water into hot dry air. | |
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| ===Mesoscopic heat engines===
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| Mesoscopic heat engines are nanoscale devices that may serve the goal of processing heat fluxes and perform useful work at small scales. Potential applications include e.g. electric cooling devices.
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| In such mesoscopic heat engines, work per cycle of operation fluctuates due to thermal noise.
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| There is exact equality that relates average of exponents of work performed by any heat engine and the heat transfer from the hotter heat bath.<ref name='sinitsyn-11jpa'>{{cite journal|title=Fluctuation Relation for Heat Engines|author=N. A. Sinitsyn |journal=J. Phys. A: Math. Theor.|volume=44|year=2011|page=405001}}</ref> <!-- N.A. Sinitsyn 2011 JPA ''44''' 405001 --> This relation transforms the Carnot's inequality into exact equality.
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| ==Efficiency==
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| The efficiency of a heat engine relates how much useful work is output for a given amount of heat energy input.
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| From the laws of [[thermodynamics]]:
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| ::<math> dW \ = \ dQ_c \ - \ (-dQ_h) </math>
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| :where | |
| ::<math> dW = -PdV </math> is the work extracted from the engine. (It is negative since work is ''done by'' the engine.)
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| ::<math> dQ_h = T_hdS_h </math> is the heat energy taken from the high temperature system. (It is negative since heat is extracted from the source, hence <math>(-dQ_h)</math> is positive.)
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| ::<math> dQ_c = T_cdS_c </math> is the heat energy delivered to the cold temperature system. (It is positive since heat is added to the sink.)
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| 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.
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| 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 out" to "what you put in."
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| In the case of an engine, one desires to extract work and puts in a heat transfer.
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| ::<math>\eta = \frac{-dW}{-dQ_h} = \frac{-dQ_h - dQ_c}{-dQ_h} = 1 - \frac{dQ_c}{-dQ_h}</math>
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| 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 [[Carnot heat engine]], although other engines using different cycles can also attain maximum efficiency. Mathematically, this is because in [[Thermodynamic reversibility|reversible]] processes, the change in [[entropy]] of the cold reservoir is the negative of that of the hot reservoir (i.e., <math>dS_c = -dS_h</math>), keeping the overall change of entropy zero. Thus:
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| ::<math>\eta_\text{max} = 1 - \frac{T_cdS_c}{-T_hdS_h} = 1 - \frac{T_c}{T_h}</math>
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| where <math>T_h</math> is the [[absolute temperature]] of the hot source and <math>T_c</math> that of the cold sink, usually measured in [[kelvin]]. Note that <math>dS_c</math> is positive while <math>dS_h</math> 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.
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| 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 statistically improbable to the point of exclusion, the Carnot efficiency is a theoretical upper bound on the reliable efficiency of ''any'' process.
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| Empirically, no heat engine has ever been shown to run at a greater efficiency than a Carnot cycle heat engine.
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| Figure 2 and Figure 3 show variations on Carnot cycle efficiency. Figure 2 indicates how efficiency changes with an increase in the heat addition temperature for a constant compressor inlet temperature. Figure 3 indicates how the efficiency changes with an increase in the heat rejection temperature for a constant turbine inlet temperature.
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| {| cellpadding="2" style="border:1px solid darkgrey; margin:auto;"
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| | [[Image:GFImg3.png|thumb|none|450px|Figure 2: Carnot cycle efficiency with changing heat addition temperature.]]
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| | [[Image:GFImg4.png|thumb|none|450px|Figure 3: Carnot cycle efficiency with changing heat rejection temperature.]]
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| |}
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| ===Endoreversible heat engines===
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| The most 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 because ''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. | |
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| A different measure of ideal heat engine efficiency is given by considerations of [[endoreversible thermodynamics]], where the cycle is identical to the Carnot cycle except in that the two processes of heat transfer are ''not'' reversible (Callen 1985):
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| ::<math>\eta = 1 - \sqrt{\frac{T_c}{T_h}}</math> (Note: Units [[kelvin|K]] or [[Rankine scale|°R]])
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| This model does a better job of predicting how well real-world heat engines can do (Callen 1985, see also [[endoreversible thermodynamics]]):
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| {| class="wikitable"
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| |+'''Efficiencies of power stations'''{{citation needed|date=April 2013}}
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| ! ''Power station'' !! <math>T_c</math> (°C) !! <math>T_h</math> (°C) !! <math>\eta</math> (Carnot) !! <math>\eta</math> (Endoreversible) !! <math>\eta</math> (Observed)
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| |-
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| ! [[West Thurrock]] (UK) [[coal-fired power station]]
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| | 25 || 565 || 0.64 || 0.40 || 0.36
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| |-
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| ! [[CANDU reactor|CANDU]] (Canada) [[nuclear power station]]
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| | 25 || 300 || 0.48 || 0.28 || 0.30
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| |-
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| ! [[Larderello]] (Italy) [[Geothermal power|geothermal power station]]
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| | 80 || 250 || 0.33 || 0.178 || 0.16
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| |}
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| As shown, the endoreversible efficiency much more closely models the observed data.
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| ==History==
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| {{Main|Timeline of heat engine technology}}
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| {{See also|History of the internal combustion engine|History of thermodynamics}}
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| Heat engines have been known since antiquity but were only made into useful devices at the time of the industrial revolution in the 18th century. They continue to be developed today.
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| ==Heat engine enhancements==
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| Engineers have studied the various heat engine cycles extensively in 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.
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| # Increase the temperature difference in the heat engine. The simplest way to do this is to increase the hot side temperature, which is the approach used in modern combined-cycle [[gas turbine]]s. Unfortunately, physical limits (such as the melting point of the materials from which the engine is constructed) and environmental concerns regarding [[NOx|NO<sub>x</sub>]] production restrict the maximum temperature on workable heat engines. Modern gas turbines run at temperatures as high as possible within the range of temperatures necessary to maintain acceptable NO<sub>x</sub> output {{Citation needed|date=January 2010}}. Another way of increasing efficiency is to lower the output temperature. One 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.
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| # Exploit the physical properties of the working fluid. The most common such exploitation 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 [[Carbon dioxide|CO<sub>2</sub>]]. [[Sulfur dioxide|SO<sub>2</sub>]] and [[xenon]] have also been considered for such applications, although SO<sub>2</sub> is a little toxic for most.
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| # 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]] (NO<sub>2</sub>), a toxic component of smog, which has a natural [[Dimer (chemistry)|dimer]] as di-nitrogen tetraoxide (N<sub>2</sub>O<sub>4</sub>). At low temperature, the N<sub>2</sub>O<sub>4</sub> is compressed and then heated. The increasing temperature causes each N<sub>2</sub>O<sub>4</sub> to break apart into two NO<sub>2</sub> molecules. This lowers the molecular weight of the working fluid, which drastically increases the efficiency of the cycle. Once the NO<sub>2</sub> has expanded through the turbine, it is cooled by the [[heat sink]], which causes it to recombine into N<sub>2</sub>O<sub>4</sub>. This is then fed back by the compressor for another cycle. Such species as [[aluminium bromide]] (Al<sub>2</sub>Br<sub>6</sub>), NOCl, and Ga<sub>2</sub>I<sub>6</sub> have all been investigated for such uses. To date, their drawbacks have not warranted their use, despite the efficiency gains that can be realized.<ref>{{cite web|url=https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Nuclear%20Reactors%20Concepts%20and%20Thermodynamic%20Cycles.pdf |title=Nuclear Reactors Concepts and Thermodynamic Cycles |format=PDF |date= |accessdate=2012-03-22}}</ref>
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| ==Heat engine processes==
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| {{Table of thermodynamic cycles}}
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| Each process is one of the following:
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| * [[isothermal process|isothermal]] (at constant temperature, maintained with heat added or removed from a heat source or sink)
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| * [[isobaric process|isobaric]] (at constant pressure)
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| * [[isochoric process|isometric/isochoric]] (at constant volume), also referred to as iso-volumetric
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| * [[adiabatic process|adiabatic]] (no heat is added or removed from the system during adiabatic process)
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| * [[isentropic process|isentropic]] (reversible adiabatic process, no heat is added or removed during isentropic process)
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| ==See also==
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| {{Portal|Energy}}
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| * [[Heat pump]]
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| * [[Reciprocating engine]] for a general description of the mechanics of piston engines
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| * [[Thermosynthesis]]
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| * [[Timeline of heat engine technology]]
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| ==References==
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| {{Reflist}}
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| ;Notes
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| {{Refbegin}}
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| * {{Cite book | last = Kroemer | first = Herbert | coauthors = Kittel, Charles | title = Thermal Physics | edition = 2nd ed. | publisher = W. H. Freeman Company | year = 1980 | isbn = 0-7167-1088-9 }}
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| * {{Cite book | last = Callen | first = Herbert B. | title = Thermodynamics and an Introduction to Thermostatistics | edition = 2nd ed. | publisher = John Wiley & Sons, Inc. | year = 1985 | isbn = 0-471-86256-8 }}
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| *[http://www.mikes-steam-engines.co.uk/other_engines.htm On line museum of toy steam engines, including a very rare Bing heat engine]
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| {{Refend}}
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| ==External links==
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| * [http://www.icefoundry.org/how-stirling-engine-works.php Video of Stirling engine running on dry ice]
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| * [http://www.taftan.com/thermodynamics/HENGINE.HTM Heat Engine]
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| {{Heat engines|state=uncollapsed}}
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| {{Thermodynamic cycles}}
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| {{DEFAULTSORT:Heat Engine}}
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| [[Category:Concepts in physics]]
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| [[Category:Engines]]
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| [[Category:Thermodynamics]]
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| [[Category:Energy conversion]]
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| [[Category:Heating, ventilating, and air conditioning]]
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