建筑环境与设备工程 外文翻译.docx

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1、本科毕业设计（论文）中英文翻译专业名称：建筑环境与设备工程年级班级：学号学生姓名：指导教师：李XX大学土木工程学院英文文献AirConditioningSystemsAirconditioninghasrapid1ygrownoverthepast50years,fromaIuxurytoastandardsysteminc1udedinmostresidentia1andcommercia1bui1dings.In1970,36%ofresidencesintheU.S.wereeitherfu11yairconditionedoruti1izedaroomairconditionerfor

2、coo1ing(B1ue,eta1.,1979),By1997,thisnumberhadmorethandoub1edto77%,andthatyeara1somarkedthefirsttimethatoverha1f(50.9%)ofresidencesintheU.S.hadcentra1airconditioners(CensusBureau,1999).Anestimated83%ofa11newhomesconstructedin1998hadcentra1airconditioners(CensusBureau,1999).Airconditioninghasa1sogrown

3、rapid1yincommercia1bui1dings.From1970to1995,thepercentageofcommercia1buiIdingswithairconditioningincreasedfrom54to73%(JacksonandJohnson,1978,andDOE,1998).Airconditioninginbui1dingsisusua11yaccomp1ishedwiththeuseofmechanica1orheat-activatedequipment.Inmostapp1ications,theairconditionermustprovideboth

4、coo1inganddehumidificationtomaintaincomfortinthebui1ding.Airconditioningsystemsarea1sousedinotherapp1ications,suchasautomobi1es,trucks,aircraft,ships,andindustria1faci1ities.However,thedescriptionofequipmentinthischapteris1imitedtothosecommon1yusedincommercia1andresidentia1bui1dings.Commercia1bui1di

5、ngsrangefrom1argehigh-riseofficebui1dingstothecornerconveniencestore.Becauseoftherangeinsizeandtypesofbui1dingsinthecommercia1sector,thereisawidevarietyofequipmentapp1iedinthesebui1dings.For1argerbui1dings,theairconditioningequipmentispartofatota1systemdesignthatinc1udesitemssuchasapipingsystem,aird

6、istributionsystem,andcoo1ingtower.Properdesignofthesesystemsrequiresaqua1ifiedengineer.Theresidentia1bui1dingsectorisdominatedbysing1efami1yhomesand1ow-riseapartments/condominiurns.Thecoo1ingequipmentapp1iedinthesebui1dingscomesinStandard“packages“thatareoftenbothsizedandinsta11edbytheairConditionin

7、gcontractor.Thechapterstartswithagenera1discussionofthevaporcompressionrefrigerationcyc1ethenmovestorefrigerantsandtheirse1ection,fo1iowedbypackagedCMIIedWaterSystemso1.1VaporCompressionCyc1eEventhoughthereisa1argerangeinsizesandvarietyofairconditioningsystemsusedinbui1dings,mostsystemsuti1izethevap

8、orcompressioncyc1etoproducethedesiredcoo1inganddehumidification.Thiscyc1eisa1sousedforrefrigeratingandfreezingfoodsandforautomotiveairconditioning.Thefirstpatentonamechanica11ydrivenrefrigerationsystemwasissuedtoJacobPerkinsin1834in1ondon,andthefirstviab1ecommercia1systemwasproducedin1857byJamesHarr

9、isonandD.E.Siebe.Besidesvaporcompression,therearetwo1esscommonmethodsusedtoproducecoo1inginbui1dings：theabsorptioncyc1eandevaporativecoo1ing.Thesearedescribed1aterinthechapter.Withthevaporcompressioncyc1e,aworkingf1uid,whichisca11edtherefrigerant,evaporatesandcondensesatsuitab1epressuresforpractica1

10、equipmentdesigns.Thefourbasiccomponentsineveryvaporcompressionrefrigerationsystemarethecompressor,condenser,expansiondevice,andevaporator.Thecompressorraisesthepressureoftherefrigerantvaporsothattherefrigerantsaturationtemperatureiss1ight1yabovethetemperatureofthecoo1ingmediumusedinthecondenser.Thet

11、ypeofcompressoruseddependsontheapp1icationofthesystem.1argee1ectricchi11erstypica1Iyuseacentrifuga1compressorwhi1esma11residentia1equipmentusesareciprocatingorscro11compressor.Thecondenserisaheatexchangerusedtorejectheatfromtherefrigeranttoacoo1ingmedium.Therefrigerantentersthecondenserandusua11y1ea

12、vesasasubcoo1ed1iquid.Typica1coo1ingmediumsusedincondensersareairandwater.Mostresidentia1-sizedequipmentusesairasthecoo1ingmediuminthecondenser,whi1emany1argerchi11ersusewater.After1eavingthecondenser,the1iquidrefrigerantexpandstoa1owerpressureintheexpansionva1ve.Theexpansionva1vecanbeapassivedevice

13、,suchasacapi11arytubeorshorttubeorifice,oranactivedevice,suchasatherma1expansionva1veore1ectronicexpansionva1ve.Thepurposeoftheva1veistoreguIatethef1owofrefrigeranttotheevaporatorsothattherefrigerantissuperheatedwhenitreachesthesuctionofthecompressor.Attheexitoftheexpansionva1ve,therefrigerantisatat

14、emperaturebe1owthatofthemedium(airorwater)tobecoo1ed.Therefrigeranttrave1sthroughaheatexchangerca11edtheevaporator.Itabsorbsenergyfromtheairorwatercircu1atedthroughtheevaporator.Ifairiscircu1atedthroughtheevaporator,thesystemisca11edadirectexpansionsystem.Ifwateriscircu1atedthroughtheevaporator,itis

15、ca11edachi11er.Ineithercase,therefrigerantdoesnotmakedirectcontactwiththeairorwaterintheevaporator.Therefrigerantisconvertedfroma1owqua1ity,two-phasef1uidtoasuperheatedvaporundernorma1operatingconditionsintheevaporator.ThevaporformedmustberemovedbythecompressorataSUffiCientratetomaintainthe1owpressu

16、reintheevaporatorandkeepthecyc1eoperating.A11mechanica1coo1ingresu1tsintheproductionofheatenergythatmustberejectedthroughthecondenser.Inmanyinstances,thisheatenergyisrejectedtotheenvironmentdirect1ytotheairinthecondenserorindirect1ytowaterwhereitisrejectedinacoo1ingtower.Withsomeapp1ications,itispossib1etouti1izethiswasteheatenergytoprovidesimu1taneousheatingtothebui1ding.Recoveryofthiswasteheatattemperaturesupto65(150oF)canbeusedtoreducecostsfors