制冷原理方法ppt课件.ppt

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1、动力机械基础PowerEngineeringEssentialCourseintroductionLimitedselectivecourse（限选课程）Durationofthecourse：32+32academichoursFinalexamination：penexamContentsandcoursestructure：Thecourseisdividedintotwoterms,inthefirstterm,studentsmaylearnsomeintroductivematerialsaboutt

2、hermalandpowerengineering,includinginternalcombustionengine（内燃机）,turbomachinery（涡轮机械）,thermalengineering(热能工程）andrefrigeration&lowtemperatureengineering（制冷及低温工程）.Inthesecondterm,studentswilllearnsomespecificbasicknowledgeintheirmajorfields.IntroductionBasicva

3、porcompressionrefrigerationcycleAbsorptionrefrigerationcycleIntroductionHeattransfermethodsRefrigerationCryogenicsThermalinsulationRefrigerationloadRefrigerationmethodsRefrigerationapplicationHeattransfermethodsConduction:Convection:Radiation:Heatistransferre

4、dfromthesourcetotheobjectbydirectphysicalcontact.Conductivity(heatcarryingqualitiesofthematerialsthroughwhichtheheatmustpass)Heatiscarriedfromhottocoldbodybymovementofconveyingsubstance.SpeedRadiantheattravelsinraysdirectlythroughspacefromahottoacoldbodyTempe

5、raturedifferenceColorofthebodywhichreceivestheheatDefinitionofrefrigerationThereisanaturaltendencytowardthermalequilibrium（热平衡）,i.e.towarduniformityoftemperature.Thenaturaltendencycanbechangedonlybytheinputofenergy.Theprocessofusingenergytocooltobelowambienta

6、ndmaintainthelowtemperatureisknownasrefrigeration(制冷）.CryogenicsTheuseofrefrigerationtoachieveverylowtemperature(downalmosttoabsolutezero)isknownascryogenics.Itisusedtodaymainlyforliquefaction.ThermalinsulationThereisalwaysacontinuousflowofheatintotherefriger

7、atedregionfromthewarmersurroundings.Tolimittheflowofheatintotherefrigeratedregiontosomepracticalminimum,itisusuallynecessarytoisolatetheregionfromitssurroundingswithagoodinsulatingmaterial.RefrigerationloadTherateatwhichheatmustberemovedfromtherefrigeratedspa

8、ceormaterialinordertoproduceandmaintainthedesiredtemperatureconditionsiscalledtherefrigerationload,thecoolingload,ortheheatload.Thesumoftheheatgainsfromseveraldifferentsources:Theheattran