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[[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.]]

[[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: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.''

:''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''' (AC) 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.  

An '''air conditioner''' (AC) 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. Whenever [[Refrigeration]] is added it is referred to as HVACR. 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 an air conditioner is to change adverse temperatures.

In construction, a complete system of heating, ventilation, and air conditioning is called HVAC. Whenever [[Refrigeration]] is added it is called HVACR. 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 an air conditioner is to change adverse temperatures.

 

== History ==

==History==

 

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 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]], [[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|access-date=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.

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|access-date=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==

Air conditioning engineers broadly divide air conditioning applications into ''comfort'' and ''process''.  

Air conditioning engineers broadly divide air conditioning applications into ''comfort'' and ''process''.  

* Food Cooking and Processing Areas

* Food Cooking and Processing Areas

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.)

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.)

== 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.]]

[[File:Compressor Danfoss SC18CL.jpg|thumb|A compressor like you would see in a [[Refrigerator]]]]

[[File:Compressor Danfoss SC18CL.jpg|thumb|A compressor like you would see in a [[Refrigerator]].]]

In the [[Heat pump and refrigeration cycle|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 refrigerated air conditioning system works in much the same way, pumping heat out of the room in which it stands.

In the [[Heat pump and refrigeration cycle|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 refrigerated air conditioning system works in much the same way, pumping heat out of the room in which it stands.

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. They do this in a [[Condenser (refrigeration)|Condenser]] and a [[Evaporator (refrigeration)|Evaporator]] 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 vapor is compressed and forced through another heat exchange coil, condensed into a liquid which then rejects 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. They do this in a [[Condenser (refrigeration)|Condenser]] and a [[Evaporator (refrigeration)|Evaporator]] 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 vapor 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==

== Air Conditioner Media ==

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>{{Cite web |url=http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=22591 |title=Home Control of Asthma & Allergies |access-date=2007-06-30 |archive-date=2009-06-18 |archive-url=https://web.archive.org/web/20090618051853/http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=22591 |url-status=dead }}</ref>

File:Split a soffitto 1.jpg|Ceiling-mounted cassette air conditioner and a wall-mounted air conditioner in the background ([[Italy]], 2017)

 

File:ACFujitsu2.jpg|An array of air conditioner condenser units outside a commercial office building

 

File:Willis Carrier 1915.jpg|[[Willis Carrier]], who is credited with building the first modern electrical air conditioning unit

 

File:GALANZ II.jpg|Evaporator, indoor unit, or terminal, side of a ductless split-type air conditioner

 

File:Industrial air conditioning unit (DFdB).JPG|An industrial air conditioning unit on top of the shopping mall ''Passage'' in Linz, Austria

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

File:Osaka Municipal Subway 10 series EMU 021.JPG|Rooftop [[Condenser (heat transfer)|condenser]] unit fitted on top of an [[Osaka Municipal Subway 10 series]] [[Rapid transit|subway]] carriage. Air conditioning has become increasingly prevalent on [[public transport]] vehicles as a form of [[climate control]], and to ensure passenger comfort and drivers' [[occupational safety and health]].

{{reflist}}

{{reflist}}

 

== Related pages ==

==Related pages==

* [[Energy]]

* [[Energy]]

* [[Heat pump]]

* [[Heat pump]]

* [[Renewable energy]]

* [[Renewable energy]]

 

== Other websites ==

==Other websites==

*[http://videos.howstuffworks.com/air-conditioner-video.htm How Air Conditioners Work] {{Webarchive|url=https://web.archive.org/web/20080718204018/http://videos.howstuffworks.com/air-conditioner-video.htm |date=2008-07-18 }}.

*[http://videos.howstuffworks.com/air-conditioner-video.htm How Air Conditioners Work] {{Webarchive|url=https://web.archive.org/web/20080718204018/http://videos.howstuffworks.com/air-conditioner-video.htm |date=2008-07-18 }}.

*[http://www.nyc.net.au/node/149398 History of Automotive Air Conditioning] {{Webarchive|url=https://web.archive.org/web/20160111133623/http://www.nyc.net.au/node/149398 |date=2016-01-11 }} on NYC.net

*[http://www.nyc.net.au/node/149398 History of Automotive Air Conditioning] {{Webarchive|url=https://web.archive.org/web/20160111133623/http://www.nyc.net.au/node/149398 |date=2016-01-11 }} on NYC.net

 

== Energy Efficiency ==

===Energy Efficiency===

* [http://www.aceee.org/consumerguide/topcac.htm Consumer Guide to Home Energy Savings - Central Air Conditioners] {{Webarchive|url=https://web.archive.org/web/20060517073456/http://www.aceee.org/consumerguide/topcac.htm |date=2006-05-17 }} from the American Council for an Energy Efficient Economy (ACEEE)

* [http://www.aceee.org/consumerguide/topcac.htm Consumer Guide to Home Energy Savings - Central Air Conditioners] {{Webarchive|url=https://web.archive.org/web/20060517073456/http://www.aceee.org/consumerguide/topcac.htm |date=2006-05-17 }} from the American Council for an Energy Efficient Economy (ACEEE)

* [http://www.aceee.org/new/eedb.htm Energy Efficiency Program Database] {{Webarchive|url=https://web.archive.org/web/20070629022444/http://www.aceee.org/new/eedb.htm |date=2007-06-29 }} from the ACEEE

* [http://www.aceee.org/new/eedb.htm Energy Efficiency Program Database] {{Webarchive|url=https://web.archive.org/web/20070629022444/http://www.aceee.org/new/eedb.htm |date=2007-06-29 }} from the ACEEE