毕业设计外文翻译gql

RefrigerationSystemPerformanceusingLiquid-SuctionHeatExchangersAbstractHeattransferdevicesareprovidedinmanyrefrigerationsystemstoexchangeenergybetWeenthecoolgaseousrefrigerantleavingtheevaporatorandWarmliquidrefrigerantexitingthecondenser.Theseliquid-suctionorsuction-lineheatexchangerscan,insomecases,yieldimprovedsystemperformanceWhileinothercasestheydegradesystemperformance.Althoughpreviousresearchershaveinvestigatedperformanceofliquid-suctionheatexchangers,thisstudycanbedistinguishedfromthepreviousstudiesinthreeWays.First,thispaperidentifiesaneWdimensionlessgrouptocorrelateperformanceimpactsattributabletoliquid-suctionheatexchangers.Second,thepaperextendspreviousanalysestoincludeneWrefrigerants.Third,theanalysisincludestheimpactofpressuredropsthroughtheliquid-suctionheatexchangeronsystemperformance.ItisshoWnthatrelianceonsimplifiedanalysistechniquescanleadtoinaccurateconclusionsregardingtheimpactofliquid-suctionheatexchangersonrefrigerationsystemperformance.Fromdetailedanalyses,itcanbeconcludedthatliquid-suctionheatexchangersthathaveaminimalpressurelossontheloWpressuresideareusefulforsystemsusingR507A,R134a,R12,R404A,R290,R407C,R600,andR410A.Theliquid-suctionheatexchangerisdetrimentaltosystemperformanceinsystemsusingR22,R32,andR717.IntroductionLiquid-suctionheatexchangersarecommonlyinstalledinrefrigerationsystemsWiththeintentofensuringpropersystemoperationandincreasingsystemperformance.Specifically,ASHRAE(1998)statesthatliquid-suctionheatexchangersareeffectivein:1)increasingthesystemperformance2)subcoolingliquidrefrigeranttopreventflashgasformationatinletstoexpansiondevices3)fullyevaporatinganyresidualliquidthatmayremainintheliquid-suctionpriortoreachingthecompressor(s)Figure1illustratesasimpledirect-expansionvaporcompressionrefrigerationsystemutilizingaliquid-suctionheatexchanger.Inthisconfiguration,hightemperatureliquidleavingtheheatrejectiondevice(anevaporativecondenserinthiscase)issubcooledpriortobeingthrottledtotheevaporatorpressurebyanexpansiondevicesuchasathermostaticexpansionvalve.ThesinkforsubcoolingtheliquidisloWtemperaturerefrigerantvaporleavingtheevaporator.Thus,theliquid-suctionheatexchangerisanindirectliquid-to-vaporheattransferdevice.Thevapor-sideoftheheatexchanger(betWeentheevaporatoroutletandthecompressorsuction)isoftenconfiguredtoserveasanaccumulatortherebyfurtherminimizingtheriskofliquidrefrigerantcarrying-overtothecompressorsuction.IncasesWheretheevaporatoralloWsliquidcarry-over,theaccumulatorportionoftheheatexchangerWilltrapand,overtime,vaporizetheliquidcarryoverbyabsorbingheatduringtheprocessofsubcoolinghigh-sideliquid.BackgroundStoeckerandWalukas(1981)focusedontheinfluenceofliquid-suctionheatexchangersinbothsingletemperatureevaporatoranddualtemperatureevaporatorsystemsutilizingrefrigerantmixtures.Theiranalysisindicatedthatliquid-suctionheatexchangersyieldedgreaterperformanceimprovementsWhennonazeotropicmixturesWereusedcomparedWithsystemsutilizingsinglecomponentrefrigerantsorazeoptropicmixtures.McLinden(1990)usedtheprincipleofcorrespondingstatestoevaluatetheanticipatedeffectsofneWrefrigerants.HeshoWedthattheperformanceofasystemusingaliquid-suctionheatexchangerincreasesastheidealgasspecificheat(relatedtothemolecularcomplexityoftherefrigerant)increases.DomanskiandDidion(1993)evaluatedtheperformanceofninealternativestoR22includingtheimpactofliquid-suctionheatexchangers.Domanskietal.(1994)laterextendedtheanalysisbyevaluatingtheinfluenceofliquid-suctionheatexchangersinstalledinvaporcompressionrefrigerationsystemsconsidering29differentrefrigerantsinatheoreticalanalysis.Bivensetal.(1994)evaluatedaproposedmixturetosubstituteforR22inairconditionersandheatpumps.Theiranalysisindicateda6-7%improvementforthealternativerefrigerantsystemWhensystemmodificationsincludedaliquid-suctionheatexchangerandcounterfloWsystemheatexchangers(evaporatorandcondenser).Bittleetal.(1995a)conductedanexperimentalevaluationofaliquid-suctionheatexchangerappliedinadomesticrefrigeratorusingR152a.TheauthorscomparedthesystemperformanceWiththatofatraditionalR12-basedsystem.Bittleetal.(1995b)alsocomparedtheASHRAEmethodforpredictingcapillarytubeperformance(includingtheeffectsofliquid-suctionheatexchangers)Withexperimentaldata.PredictedcapillarytubemassfloWratesWereWithin10%ofpredictedvaluesandsubcoolinglevelsWereWithin1.7C(3F)ofactualmeasurements.Thispaperanalyzestheliquid-suctionheatexchangertoquantifyitsimpactonsystemcapacityandperformance(expressedintermsofasystemcoefficientofperformance,COP).Theinfluenceofliquid-suctionheatexchangersizeoverarangeofoperatingconditions(evaporatingandcondensing)isillustratedandquantifiedusinganumberofalternativerefrigerants.RefrigerantsincludedinthepresentanalysisareR507A,R404A,R600,R290,R134a,R407C,R410A,R12,R22,R32,andR717.ThispaperextendstheresultspresentedinpreviousstudiesinthatitconsidersneWrefrigerants,itspecificallyconsiderstheeffectsofthepressuredrops,anditpresentsgeneralrelationsforestimatingtheeffectofliquid-suctionheatexchangersforanyrefrigerant.HeatExchangerEffectivenessTheabilityofaliquid-suctionheatexchangertotransferenergyfromtheWarmliquidtothecoolvaporatsteady-stateconditionsisdependentonthesizeandconfigurationoftheheattransferdevice.Theliquid-suctionheatexchangerperformance,expressedintermsofaneffectiveness,isaparameterintheanalysis.Theeffectivenessoftheliquid-suctionheatexchangerisdefinedinequation(1):Wherethenumericsubscriptedtemperature(T)valuescorrespondtolocationsdepictedinFigure1.Theeffectivenessistheratiooftheactualtomaximumpossibleheattransferrates.Itisrelatedtothesurfaceareaoftheheatexchanger.AzerosurfacearearepresentsasystemWithoutaliquid-suctionheatexchangerWhereasasystemhavinganinfiniteheatexchangerareacorrespondstoaneffectivenessofunity.Theliquid-suctionheatexchangereffectstheperformanceofarefrigerationsystembyinfluencingboththehighandloWpressuresidesofasystem.Figure2shoWsthekeystatepointsforavaporcompressioncycleutilizinganidealizedliquid-suctionheatexchangeronapressure-enthalpydiagram.Theenthalpyoftherefrigerantleavingthecondenser(state3)isdecreasedpriortoenteringtheexpansiondevice(state4)byrejectingenergytothevaporrefrigerantleavingtheevaporator(state1)priortoenteringthecompressor(state2).PressurelossesarenotshoWn.Thecoolingofthecondensatethatoccursonthehighpressuresideservestoincreasetherefrigerationcapacityandreducethelikelihoodofliquidrefrigerantflashingpriortoreachingtheexpansiondevice.OntheloWpressureside,theliquid-suctionheatexchangerincreasesthetemperatureofthevaporenteringthecompressorandreducestherefrigerantpressure,bothofWhichincreasethespecificvolumeoftherefrigerantandtherebydecreasethemassfloWrateandcapacity.Amajorbenefitoftheliquid-suctionheatexchangeristhatitreducesthepossibilityofliquidcarry-overfromtheevaporatorWhichcouldharmthecompressor.LiquidcarryovercanbereadilycausedbyanumberoffactorsthatmayincludeWidefluctuationsinevaporatorloadandpoorlymaintainedexpansiondevices(especiallyproblematicforthermostaticexpansionvalvesusedinammoniaservice).（翻译）冷却系统利用流体吸热交换器摘录盛加热装置跳在许多冷吉却系统中惩被用到，膛用以制冷食时遗留在邻蒸发器中弹的冷却气伞体和离开殿冷凝器发珍热流体之租间的能量夜的热交后换绢.炸这些流体捧吸收或吸套收热交换部器暗,慌在一些情蛮形中，他栏们降低了早系统性副能糕,毒蓬然而系统谢的某些地租方却得到企了改药善江.窗梳虽然以前胀研究员已思经调查了激流体吸热锯交换器的壳性民能职,田今但是这项网研究可能蚕从早先研抛究的三种侨方式被加泄以区确别俭.做包首先，这个份研究开寻辟了一个府无限的崭伴新的与流晓体吸热交幅换器有关登联的群猪体径.挣其次，这帐份研究拓飘宽了早先配的分析包齐括新型制笔冷剂。第宣三史,拢次研究包括驳压力的冲添击降低了愁流体吸热比交换器的志系统性盘能渐.信普在简单的全技术信息步分析中表怀明流体吸感热交换器考对冷却系反统性能的图冲击可能栋导致错误医的结省论喇.份从详细说访明分析熟里爆,售它能得出妖一个结论堤，那就是塑液扒体欠-宪料吸加热交帅换器在低贩压区域上慨的临界压吐力使侨用浙R50饿7A痕底，艘R13仇4a梅货，行R12绑停，贴R40吨4A读史，猎R29庙0语屿，傻R407伸C掉塘，相R60贞0耍睡和想R41债0A枯这些制冷弦剂，对系裕统是有用洁的。而使秤用托R22拐她，讽R32晚卖和塌R71利7炊对系统的仰性能是有劫害气的洞.介绍赵流体吸热伴交换器被刃普遍的安都装在正确挣合适的系烂统操作和累提高系统蕉性能的制忌冷系统中完。很明显莫，两ASH瑞RAE(乱1998样)千雷液否体漆-祖慧吸加热交鼠换器的确诵是有效的阅他表现禽在虏:己1疑)夏增加系统叨性能籍2勾)罚液体制冷芒剂防止散档发气体进专入扩充装跟置。挑一些剩余灿的液体在途到达之前吵被完全蒸辟发了。爷图舟1肌度列举了一娱个简单的箩指示。压切缩辟物慕(s)押始可能利用淹流体吸热乒交换器保苍持的液体压扩充蒸汽桥压缩的性敞能反.公3线）在这一衫个结构杯中肤,稼高温液体禾余热像一蛮个温度调凶节装置一些样拒绝装誓置悔唱(效蒸发冷凝粒器就是这爹种情吐况业)具甲在扩充之闹前对蒸发疲器的压力份再冷钞却运,所洗涤槽是逼为了接收杂在低温度根冷冻下遗西留在蒸发胶器内的再锤冷却才液府.验歌因此，流事体吸热交水换器是一衫种从液体值到蒸汽热雷交换的间栗接装销置乞.姓奇热交换登器觉惠(表在蒸发器挑出口和压宿缩物吸收辣之坑间冰)领转的蒸汽边婶界经常承供担积聚压赌缩物吸的耽液体，藉踏此将对滞定留的液体摸制冷剂的咐危险性减卧到更下少垒.衣前在蒸发器凳允许液体翅滞留的情粪形沈中改,壶购在热交换勉器中积聚吨部分会困真住而且，关超过一定图的时间后朴，在液体才再冷却的缴过程中，臂滞留的液壳体被吸收巾热量而蒸题发鹊.背景歪Stoe忧cker袍窃和雀Wal桶ukas渗(198省1)猛都着重于利霉用流体吸飞热交换器俘在单一温艳度蒸发和逗双重的温胆度蒸发系签统的影响敢下的冷冻残混肠合核.挨他们的分上析指出温当倍nona臂zeot剩ropi执c嘉混合剂扛或拐azeo凤ptro课pi爹c汽混合剂与假利用单一雷成份制乘冷剂的系遍统相比较神时寸,瓣探流体吸热鸽交换器产至生更多性逃能的改进弊。妖McLi石nden巴(199刮0)挣佩用了相关判的原则评右价新的制渗冷剂被预夕期的效洽果竹.冠助他指出作惯为理想的残特殊性气衫体使用在灵流体吸热令交换器中美增加这项肃系统的性输能窄(蚕谈到制冷我剂的复杂羽的分子结遍构姻)悔。拌Dom也ansk刮i联染和方Did歇ion(迫1993恢)俱团评估了包农括流体吸月热交换器乒的替代乳品贯R22碑爪的九个性肥能垒.浴Doma门nski剪et勉al.闲(199枯4固)撤稍后鉴于帮对叠2击9施种趴考不同的制福冷剂一项夜理论分析慰，扩大了井流体吸热逗交换器安脑装在蒸汽驳压缩冷却寺系统的评驶价片Bive唉nse锈tal跟.芦(199特4土)仰评估了一坐种被提议凯的混合物屯来替代为辜空调和热杠泵中使用怖的枕R2喊2圾。他们的教分析指出灯当系统修修正包括了劈流体吸热家交换器惕和三算逆向系统肢热交换器攀的时型候友,纸寄两者之一翅的冷冻系奏统旷有竹6-7缎%叶莲进斤步有辣(蛾蒸发器和彩凝结删器胃).仓Bitt宋lee周tal泊做了一项丹评估流体滤吸热交换乳器在家用滥电冰箱中架采用制冷绢剂导R152荡a傻实验作者栋把该系统角性能与传淋统的熔以仆R12翻症为基础的胜系统作了阔一个比较闻。喉婆Bitt嫂lee元tal去把制冷与叼