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1、SECTIONTHIRTEENHEATING,VENTILATION,ANDAIRCONDITIONINGLawrenceE.McCabe*ChiefEngineer—MechanicalSTVGroupDouglassville,PennsylvaniaThenecessityofheating,ventilation,andair-conditioning(HVAC)controlofen-vironmentalconditionswithinbuildingshasbeenwellestablishedovertheyearsasbeinghigh
2、lydesirableforvarioustypesofoccupancyandcomfortconditionsaswellasformanyindustrialmanufacturingprocesses.Infact,withoutHVACsys-tems,manymanufacturedproductsproducedbyindustrythatareliterallytakenforgrantedwouldnotbeavailabletoday.13.1DEFINITIONSOFTERMSOFHEATING,VENTILATION,ANDAIR
3、CONDITIONING(HVAC)AdiabaticProcess.Athermodynamicprocessthattakesplacewithoutanyheatbeingaddedorsubtractedandatconstanttotalheat.Air,Makeup.New,orfresh,airbroughtintoabuildingtoreplacelossesduetoexfiltrationandexhausts,suchasthosefromventilationandchemicalhoods.Air,Return(Recircul
4、ated).Airthatleavesaconditionedspacedandisreturnedtotheairconditioningequipmentfortreatment.Air,Saturated.Airthatisfullysaturatedwithwatervapor(100%humidity),withtheairandwatervaporatthesametemperature.Air,Standard.Airat70F(21C)andstandardatmosphericpressure[29.92in(101.3kPa)of
5、mercury]andweighingabout0.075lb/ft3(1.20kg/m3).AirChange.Thecompletereplacementofroomairvolumewithnewsupplyair.*RevisedandupdatedfromthepreviouseditionbyFrankC.Yanocha.13.113.2SECTIONTHIRTEENAirConditioning.Theprocessofalteringairsupplytocontrolsimultaneouslyitshumidity,temperatu
6、re,cleanliness,anddistributiontomeetspecificcriteriaforaspace.Airconditioningmayeitherincreaseordecreasethespacetemper-ature.AirConditioning,Comfort.Useofairconditioningsolelyforhumancomfort,ascomparedwithconditioningforindustrialprocessesormanufacturing.AirConditioning,Industrial
7、.Useofairconditioninginindustrialplantswheretheprimeobjectiveisenhancementofamanufacturingprocessratherthanhumancomfort.BaseboardRadiation.Aheat-surfacedevice,suchasafinnedtubewithadec-orativecover.Blow.Horizontaldistancefromasupply-airdischargeregistertoapointatwhichthesupply-air
8、velocityreducesto50ft/min.Boiler.Acast-i
