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1、AirConditioningSystemsAirconditioninghasrapidlygrownoverthepast50years,fromaluxurytoastandardsystemincludedinmostresidentialandcommercialbuildings.In1970,36%ofresidencesintheU.S.wereeitherfullyairconditionedorutilizedaroomairconditionerforcooling(Blue,etal.,1979).By1997,thisnumberha
2、dmorethandoubledto77%,andthatyearalsomarkedthefirsttimethatoverhalf(50.9%)ofresidencesintheU.S.hadcentralairconditioners(CensusBureau,1999).Anestimated83%ofallnewhomesconstructedin1998hadcentralairconditioners(CensusBureau,1999).Airconditioninghasalsogrownrapidlyincommercialbuilding
3、s.From1970to1995,thepercentageofcommercialbuildingswithairconditioningincreasedfrom54to73%(JacksonandJohnson,1978,andDOE,1998).Airconditioninginbuildingsisusuallyaccomplishedwiththeuseofmechanicalorheat-activatedequipment.Inmostapplications,theairconditionermustprovidebothcoolingand
4、dehumidificationtomaintaincomfortinthebuilding.Airconditioningsystemsarealsousedinotherapplications,suchasautomobiles,trucks,aircraft,ships,andindustrialfacilities.However,thedescriptionofequipmentinthischapterislimitedtothosecommonlyusedincommercialandresidentialbuildings.Commercia
5、lbuildingsrangefromlargehigh-riseofficebuildingstothecornerconveniencestore.Becauseoftherangeinsizeandtypesofbuildingsinthecommercialsector,thereisawidevarietyofequipmentappliedinthesebuildings.Forlargerbuildings,theairconditioningequipmentispartofatotalsystemdesignthatincludesitems
6、suchasapipingsystem,airdistributionsystem,andcoolingtower.Properdesignofthesesystemsrequiresaqualifiedengineer.Theresidentialbuildingsectorisdominatedbysinglefamilyhomesandlow-riseapartments/condominiums.Thecoolingequipmentappliedinthesebuildingscomesinstandard“packages”thatareoften
7、bothsizedandinstalledbytheairconditioningcontractor.Thechapterstartswithageneraldiscussionofthevaporcompressionrefrigerationcyclethenmovestorefrigerantsandtheirselection,followedbypackagedChilledWaterSystems。1.1VaporCompressionCycleEventhoughthereisalargerangeinsizesandvarietyofairc
8、onditioningsystemsu