lesson 12轮机英语阅读.pptx

MarineRefrigeration;Thenaturaltransfer自然传递ofheat热isfromahotbodytoacoldbody.

Thefunctionofarefrigerationplant制冷装置istoactasaheatpumpandreverse逆转thisprocess过程sothatroomscanbemaintained保持atlowtemperaturesforthepreservation储存offoodstuffs食物,oraircanbecooledfortheairconditioning.

;Thecompressionrefrigeration压缩制冷isthemostcommonlyusedtypeofmarinerefrigeration.

Thebasiccomponents部件requiredforacompressionrefrigerationsystemare

compressor压缩机,

condenser冷凝器,

expansionvalve膨胀阀,and

evaporator蒸发器or

coolingcoils冷却盘管.;Therefrigeratingagent制冷介质,alsoknownasrefrigerant制冷剂,isalternately交替地vaporized汽化andliquefied液化duringtherefrigerationcycle循环.

Thetemperatureatwhichafluidboils沸腾orcondenses冷凝isknownassaturationtemperature饱和温度andvaries变化withpressure.;Thecompressor压缩机inarefrigerationsystemraisesthepressureofthevaporizedrefrigerant汽化制冷剂aswellasitssaturationtemperature,whichishigherthanthatoftheseawaterusedforcoolingthecondenser.

Thecompressoralsopromotescirculation循环oftherefrigerantbypumpingitaroundthesystem.

;Inthecondenser冷凝器,thevaporizedrefrigerantisliquefiedbycirculatingseawater.

Latentheat潜热,originallyfromtheevaporator蒸发器,isthustransferredtothecoolingmedium.

Theliquidrefrigerant液态制冷剂,stillatthepressureproducedbythecompressor,passestothereceiverandthentotheexpansionvalve膨胀阀.

;Theexpansionvalve膨胀阀isaregulator调节器throughwhichtherefrigerantflowsfromthehighpressureside高压侧ofthesystemtothelowpressureside低压侧.

Itthrottles节流theliquidrefrigerantbyasmallorifice孔口andmaintainsthepressuredifferencebetweenthecondenserandtheevaporator,whilesupplyingrefrigeranttotheevaporatoratthecorrectrate.

Itisthermostatically恒温地controlledinFreonsystem.

;Infact，astheliquidpassesthroughtheexpansionvalve,thepressuredropmakesitssaturationtemperatu