汽车专业实用英语 教学课件 作者 陈晟闽 12-Air Conditioning Operation.ppt

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1、WelcomeToAirConditioningOperation&DiagnosisSECTION122SystemComponentsAllsystemscontainsixmajorcomponents:CompressortocirculatetherefrigerantCondensertotransferheattoambientairReceiverdryeroraccumulatortostorereserverefrigerant,containthedesiccant,andfilterrefrigerantExpansiondevicetocont

2、rolamountofrefrigerantenteringevaporatorEvaporatortotransferheatfromin-vehicleairtotherefrigerantLinesandhosestoconnectthesepartstogetherAndtherefrigerant3AutomotiveA/CSystems2primarysystemsusedtocontrolevaporatorpressureandtemperature:TXVsystems(thermalorthermostaticexpansionvalve)OTsys

3、tems(orificetube)FixedVariable4LowSideOperationGoalistoprovideconstantevaporatortemperatureof32degreesRefrigerantshavelowboilingpointsWhenliquidboils,itabsorbslargeamountsofheatAmountofheatabsorbedinevaporatorisproportionaltoamountofrefrigerantboiled5LowSideComponentsExpansiondeviceEvapo

4、ratorAccumulator(ifequipped)6ExpansionDevicesTheexpansiondeviceseparatesthehighsidefromthelowsideandprovidesarestrictionforthecompressortopumpagainst.Therearetwostylesofexpansiondevices:TheTXVcanopenorclosetochangeflow.Itiscontrolledbythesuperheatspring,thermalbulbthatsensesevaporatorout

5、lettemperature,andevaporatorpressureMostOTshaveafixeddiameterorifice7ATXVcontrolstherefrigerantflowfromthehighpressuresidetotheevaporator.AreceiverdryerismountedintheliquidlineofallTXVsystems.TXVSystemAnimation:A/CSystems,TXV8AnOTcontrolstherefrigerantflowfromthehighpressuresidetotheevap

6、orator.AnaccumulatorismountedinthesuctionlineofallOTsystems.Animation:A/CSystems,OTOTSystem9ThermalExpansionValves,TXVsThethreemajortypesofexpansionvalves:InternallybalancedTXVsarethemostcommon.ExternallybalancedTXVsareusedonsomelargerevaporators.Blockvalvesroutetherefrigerantleavingthee

7、vaporatorpastthethermalsensingdiaphragmsoathermalbulbisnotneeded.Animation:TXVOperationInternallyBalancedExternallyBalancedBlockValve10ThermalExpansionValves,TXVsVariablevalvethatcanchangesizeofopeninginresponsetosystemloadOpensorclosesdependingonevaporatorpressureandtemp