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[[Image:Single-room AC unit-external.jpg|thumb|right|The external section of a typical single-room air conditioning unit. For ease of installation, these are frequently placed in a window. This one was installed through a hole cut in the wall.]][[Image:Single-room AC unit-internal.jpg|thumb|right|The internal section of the same unit. The front panel swings down to reveal the controls.]]

[[Image:Single-room AC unit-external.jpg|thumb|The external section of a generic single-room air conditioning unit. For ease of installation, units are typically fitted into windows or, as in this photograph, a hole in the wall]][[Image:Single-room AC unit-internal.jpg|thumb|right|The internal section of the same unit. The front panel swings down to reveal the controls.]]

:''Note: "air conditioning" can refer to any form of "[[Heating]], [[ventilation]] and air-conditioning''. This article is specifically about the use of [[refrigeration]] for this purpose.''

:''Note:the term "air conditioning" refers to any form of "[[Heating]], [[ventilation]] and air-conditioning"''. This article deals specifically with units used as part of a cooling system.''

An '''air conditioner''' is a [[system]], or [[machine]] that removes heat from an area using a cycle in which heat is moved out of the area where it is hot.  

An '''air conditioner''' is a system or a machine that treats air in a defined, usually enclosed area via a refrigeration cycle in which warm air is removed and replaced with cooler air.  

In construction, a complete system of [[heating]], ventilation, and air conditioning is referred to as [[HVAC]]. Its purpose, in the home or in the car, is to provide comfort during hot days and nights.  

In construction, a complete system of heating, ventilation, and air conditioning is referred to as [[HVAC]]. Whether in homes, offices or vehicles, its purpose is to provide comfort by altering the properties of the air, usually by cooling the air inside.The main function of air conditioner is to change adverse temperature.  

==History==

==History==

The 19th century [[United Kingdom|British]] [[scientist]] and [[inventor]] [[Michael Faraday]] discovered that compressing and liquefying [[ammonia]] could chill air when the liquefied ammonia was allowed to evaporate.  

In the 19th century [[United Kingdom|British]] [[scientist]] and [[inventor]] [[Michael Faraday]] discovered that compressing and liquefying [[ammonia]] could chill air when the liquefied ammonia was allowed to evaporate.  

In [[1842]], [[Philippines]] physician [[John Gorrie|Dr. John Gorrie]] used [[Gas compressor|compressor]] technology to create [[ice]], which he used to cool air for his patients.<ref>[http://www.facstaff.bucknell.edu/mvigeant/therm_1/AC_final/bg.htm History of Air conditioning]</ref> He hoped eventually to use his ice-making machine to regulate the temperature of buildings. He even thought of centralized air conditioning that could cool entire cities.

In [[1842]], [[United States of America|American]] physician [[John Gorrie|Dr. John Gorrie]] used [[Gas compressor|compressor]] technology to create [[ice]], which he used to cool air for his patients.<ref>{{cite web|title=Gorrie Ice Machine, Patent Model|url=https://americanhistory.si.edu/collections/search/object/nmah_846192|website=National Museum of American History|accessdate=July 17, 2020}}</ref> He hoped eventually to use his ice-making machine to regulate the temperature of buildings and even considered cooling entire cities with a system of centralized air conditioning units.

==Air conditioning applications==

==Air conditioning applications==

'''''Comfort applications''''' aim to provide an indoor environment that remains relatively constant in a range [[Habitable zone|preferred by humans]] despite changes in external weather conditions or in internal heat loads.  

'''''Comfort applications''''' aim to provide an indoor environment that remains relatively constant in a range [[Habitable zone|preferred by humans]] despite changes in external weather conditions or in internal heat loads.  

'''''Process applications''''' aim to provide a suitable environment for a process being carried out, regardless of internal heat loads and external weather conditions. Although often in the comfort range, it is the needs of the process that determine conditions, not human preference. Process applications include:

'''''Process applications''''' aim to provide a suitable environment for an industrial or a commercial process, regardless of internal heat loads and external weather conditions. Although often in the same comfort range, it is the requirements of  the process that determines conditions, not human preference. Process applications include:

* Hospital [[operating room]]s in which air is filtered to high levels to reduce [[infection]] risk and the humidity controlled to limit patient dehydration. Although temperatures are often in the comfort range, some specialist procedures such as [[open heart surgery]] require low temperatures (about 18 °C, 64 °F) and others such as [[neonatal]] relatively high temperatures (about 28 °C, 82 °F).

* Hospital [[operating room]]s <nowiki/>in which air is filtered to high levels to reduce the risk of infection  and the humidity is controlled to limit patient dehydration. Although temperatures are often in the comfort range, some specialist procedures such as [[open heart surgery]] require low temperatures (about 18 °C, 64 °F), and others such as [[neonatal]] relatively high temperatures (about 28 °C, 82 °F).

* [[Cleanroom]]s for the production of [[integrated circuits]], [[pharmaceuticals]] and the like in which very high levels of air cleanliness and control of temperature and humidity are required for the success of the process.

* [[Cleanroom]]s for the production of [[integrated circuits]] and [[pharmaceuticals]]  etc. in which extremely high levels of air cleanliness and control of temperature and humidity are required for the success of the process.

* Facilities for breeding [[laboratory animal]]s. Since many animals normally only reproduce in spring, holding them in rooms at which conditions mirror spring all year can cause them to reproduce year round.

* Facilities for breeding [[laboratory animal]]s. Since many animals normally only reproduce in spring, holding them in rooms which  mirror spring-like conditions can cause them to reproduce all year round.

 

* Aircraft air conditioning. Although nominally aimed at providing comfort for passengers and cooling of equipment, aircraft air conditioning presents a special process because of the low air pressure outside the aircraft.

* Data Processing Centers

* Data Processing Centers

* Textile Factories

* Textile Factories

* Food Cooking and Processing Areas

* Food Cooking and Processing Areas

In both comfort and process applications not only is the objective to control temperature (although in some comfort applications this is all that is controlled) but other factors including [[humidity]], air movement and air quality.

In both comfort and process applications, the objective is not only to control temperature (although in some comfort applications this is all that is controlled) but also factors like [[humidity]], air movement and air quality.

== Air Conditioning System Basics and Theories ==

== Air conditioning system basics and theories ==

=== Refrigeration cycle ===

=== Refrigeration cycle ===

[[Image:Heatpump.svg|thumb|300px|A simple stylized diagram of the refrigeration cycle: 1)&nbsp;condensing coil, 2)&nbsp;expansion valve, 3)&nbsp;evaporator coil, 4)&nbsp;compressor.]]

[[Image:Heatpump.svg|thumb|300px|A simple stylized diagram of the refrigeration cycle: 1)&nbsp;condensing coil, 2)&nbsp;expansion valve, 3)&nbsp;evaporator coil, 4)&nbsp;compressor.]]

In the [[refrigeration cycle]], a [[heat pump]] transfers heat from a lower temperature heat source into a higher temperature heat sink. Heat would naturally flow in the opposite direction. This is the most common type of air conditioning.  

In the [[refrigeration cycle]], a [[heat pump|pump]] transfers heat from a lower temperature source into a higher temperature heat sink. Heat will naturally flow in the opposite direction. This is the most common type of air conditioning.  

A refrigerator works in much the same way, as it pumps the heat out of the interior into the room in which it stands.

A refrigerated air conditioning system works in much the same way pumping heat out of the room in which it stands.

This cycle takes advantage of the [[universal gas law]] ''PV'' = ''nRT'', where ''P'' is pressure, ''V'' is volume, ''R'' is the [[universal gas constant]], ''T'' is temperature, and ''n'' is the number of moles of gas (1 mole = 6.022×10²³ molecules).

This cycle takes advantage of the [[universal gas law]] ''PV'' = ''nRT'', where ''P'' is pressure, ''V'' is volume, ''R'' is the [[universal gas constant]], ''T'' is temperature, and ''n'' is the number of molecules of gas (1 mole = 6.022×10²³ molecules).

The most common refrigeration cycle uses an electric motor to drive a [[gas compressor|compressor]]. In an automobile the compressor is driven by a [[pulley]] on the engine's [[crankshaft]], with both using electric motors for air circulation. Since [[evaporation]] occurs when [[heat]] is absorbed, and [[condensation]] occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a refrigerant around. A refrigerant is pumped into the cooled compartment (the evaporator coil), where the low pressure causes the refrigerant to evaporate into a vapor, taking heat with it. In the other compartment (the condenser), the refrigerant vapour is compressed and forced through another heat exchange coil, condensing into a liquid, rejecting the heat previously absorbed from the cooled space.

The most common refrigeration cycle uses an electric motor to drive a [[gas compressor|compressor]]. In an automobile the compressor is driven by a [[pulley]] on the engine's [[crankshaft]], with both using electric motors for air circulation. Since [[evaporation]] occurs when [[heat]] is absorbed, and [[condensation]] occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a coolant around an enclosed system. The cooling liquid, or refrigerant is pumped into the cooled compartment (the evaporator coil). Low pressure then causes the refrigerant to evaporate taking the heat with it. In the other compartment (the condenser), the refrigerant vapour is compressed and forced through another heat exchange coil, condensed into a liquid which then rejects the heat previously absorbed from the cooled space.

==Health implications==

==Health implications==

Air conditioning has no greater influence on health than heating–that is to say, very little–although poorly maintained air-conditioning systems (especially large, centralized systems) can occasionally promote the growth and spread of microorganisms, such as ''[[Legionella pneumophila]],'' the infectious agent responsible for [[Legionnaire's disease]].<ref>[http://www.merck.com/mrkshared/mmanual/section6/chapter75/75e.jsp Sick building syndrome]</ref>  Air conditioning can have a positive effect on sufferers of [[allergy|allergies]] and [[asthma]].<ref>[http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=22591 Home Control of Asthma & Allergies]</ref>

Air conditioning has as much influence on human health as any generic heating system.Poorly maintained air-conditioning systems (especially large, centralized systems) can occasionally promote the growth and spread of microorganisms such as ''[[Legionella pneumophila]],'' the infectious agent responsible for [[Legionnaire's disease]].<ref>[http://www.merck.com/mrkshared/mmanual/section6/chapter75/75e.jsp Sick building syndrome]</ref>  Air conditioning can have a positive effect on sufferers of [[allergy|allergies]] and [[asthma]].<ref>[http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=22591 Home Control of Asthma & Allergies]</ref>

 

 

 

 

 

In serious [[heat wave]]s, air conditioning can save the lives of the elderly. Some local authorities even set up public [[cooling center]]s for the benefit of those without air conditioning at home.

* The external unit is necessarily in the area of ​​free circulation of air flows.  

* It is important to organize free access for further maintenance and repair of the unit.

* During operation, exhausted streams of hot air come from the equipment, therefore it must be positioned so that the fumes do not enter the windows of the lower floors.<ref>{{Cite web|url=https://prohlada.dp.ua/news/ustanovit-kondicioner-v-dnepre|title=Выбрать кондиционер в Днепре {{!}} Купить (Заказать) недорого на сайте|website=prohlada.dp.ua|access-date=2020-06-13}}</ref>

==References==

==References==

*[http://videos.howstuffworks.com/air-conditioner-video.htm How Air Conditioners Work].

*[http://videos.howstuffworks.com/air-conditioner-video.htm How Air Conditioners Work].

*[http://www.nyc.net.au/node/149398 History of Automotive Air Conditioning] on NYC.net

*[http://www.nyc.net.au/node/149398 History of Automotive Air Conditioning] on NYC.net

*[https://www.fantastichome.in/top-10-ac-in-india-june-2020/ Top 10 ac in india june 2020]

*[http://www.hvacwebconnection.com/Directory/mf_ac.htm Directory of Air Conditioning Manufacturers]

===Energy Efficiency===

===Energy Efficiency===

*[http://www.cooloff.org/ AHAM website on Room-air Conditioners]

*[http://www.cooloff.org/ AHAM website on Room-air Conditioners]

*[http://www.aceee.org/consumerguide/topcac.htm Top-Rated Energy-Efficient Central Air Conditioners]

*[http://www.aceee.org/consumerguide/topcac.htm Top-Rated Energy-Efficient Central Air Conditioners]

*[http://www.energystar.gov/index.cfm?c=cac.pr_central_ac Energy Star Central Air Conditioners]

*[http://www.energystar.gov/index.cfm?c=cac.pr_central_ac Energy Star Central Air Conditioners]

*[http://doityourself.com/aircond/index.shtml How to lower the energy usage of central air conditioning]

*[http://doityourself.com/aircond/index.shtml How to lower the energy usage of central air conditioning]

[[Category:Engineering]]

[[Category:Engineering]]