文献翻译-换热器的分类及其应用

8、英语翻译TheuseandintroductionoftheheatexchangerAheatexchangerisadevicebuiltforefficientheattransferfromonemediumtoanother,whetherthemediaareseparatedbyasolidwallsothattheynevermix,orthemediaareindirectcontact.Theyarewidelyusedinspaceheating,refrigeration,airconditioning,powerplants,chemicalplants,petrochemicalplants,petroleumrefineries,andnaturalgasprocessing.Onecommonexampleofaheatexchangeristheradiatorinacar,inwhichtheheatsource,beingahotengine-coolingfluid,water,transfersheattoairflowingthroughtheradiator.Heatexchangersmaybeclassifiedaccordingtotheirflowarrangement.Inparallel-flowheatexchangers,thetwofluidsentertheexchangeratthesameend,andtravelinparalleltooneanothertotheotherside.Incounter-flowheatexchangersthefluidsentertheexchangerfromoppositeends.Thecountercurrentdesignismostefficient,inthatitcantransferthemostheatfromtheheat(transfer)medium.Seecountercurrentexchange.Inacross-flowheatexchanger,thefluidstravelroughlyperpendiculartooneanotherthroughtheexchanger.Forefficiency,heatexchangersaredesignedtomaximizethesurfaceareaofthewallbetweenthetwofluids,whileminimizingresistancetofluidflowthroughtheexchanger.Theexchangersperformancecanalsobeaffectedbytheadditionoffinsorcorrugationsinoneorbothdirections,whichincreasesurfaceareaandmaychannelfluidfloworinduceturbulence.Thedrivingtemperatureacrosstheheattransfersurfacevarieswithposition,butanappropriatemeantemperaturecanbedefined.Inmostsimplesystemsthisisthelogmeantemperaturedifference(LMTD).SometimesdirectknowledgeoftheLMTDisnotavailableandtheNTUmethodisused.Phase-changeheatexchangersTypicalkettlereboilerusedforindustrialdistillationtowersTypicalwater-cooledsurfacecondenserInadditiontoheatinguporcoolingdownfluidsinjustasinglephase,heatexchangerscanbeusedeithertoheataliquidtoevaporate(orboil)itorusedascondenserstocoolavaporandcondenseittoaliquid.Inchemicalplantsandrefineries,reboilersusedtoheatincomingfeedfordistillationtowersareoftenheatexchangers.Distillationset-upstypicallyusecondenserstocondensedistillatevaporsbackintoliquid.Powerplantswhichhavesteam-driventurbinescommonlyuseheatexchangerstoboilwaterintosteam.Heatexchangersorsimilarunitsforproducingsteamfromwaterareoftencalledboilersorsteamgenerators.Inthenuclearpowerplantscalledpressurizedwaterreactors,speciallargeheatexchangerswhichpassheatfromtheprimary(reactorplant)systemtothesecondary(steamplant)system,producingsteamfromwaterintheprocess,arecalledsteamgenerators.Allfossil-fueledandnuclearpowerplantsusingsteam-driventurbineshavesurfacecondenserstoconverttheexhauststeamfromtheturbinesintocondensate(water)forre-use.Inordertoconserveenergyandcoolingcapacityinchemicalandotherplants,regenerativeheatexchangerscanbeusedtotransferheatfromonestreamthatneedstobecooledtoanotherstreamthatneedstobeheated,suchasdistillatecoolingandreboilerfeedpre-heating.Thistermcanalsorefertoheatexchangersthatcontainamaterialwithintheirstructurethathasachangeofphase.Thisisusuallyasolidtoliquidphaseduetothesmallvolumedifferencebetweenthesestates.Thischangeofphaseeffectivelyactsasabufferbecauseitoccursataconstanttemperaturebutstillallowsfortheheatexchangertoacceptadditionalheat.OneexamplewherethishasbeeninvestigatedisforuseinhighpoweraircraftelectronicsDynamicscrapedsurfaceheatexchangerAnothertypeofheatexchangeriscalleddynamicheatexchangerorscraped-surfaceheatexchanger.Thisismainlyusedforheatingorcoolingwithhigh-viscosityproducts,crystallizationprocesses,evaporationandhigh-foulingapplications.Longrunningtimesareachievedduetothecontinuousscrapingofthesurface,thusavoidingfoulingandachievingasustainableheattransferrateduringtheprocess.TheformulausedforthiswillbeQ=A*U*LMTD,wherebyQ=heattransferrate.FluidheatexchangersThisisaheatexchangerwithagaspassingupwardsthroughashoweroffluid(oftenwater),andthefluidisthentakenelsewherebeforebeingcooled.Thisiscommonlyusedforcoolinggaseswhilstalsoremovingcertainimpurities,thussolvingtwoproblemsatonce.Itiswidelyusedinespressomachinesasanenergy-savingmethodofcoolingsuper-heatedwatertobeusedintheextractionofespresso.PlateFinheatexchangerThistypeheatexchangerusessandwichedpassagescontainingfinstoincreasetheeffectivityoftheunit.Thedesignsincludecrossflowandcounterflowcoupledwithvariousfinconfigurationssuchasstraightfins,offsetfinsandwavyfins.AdiabaticwheelheatexchangerAfourthtypeofheatexchangerusesanintermediatefluidorsolidstoretoholdheat,whichisthenmovedtotheothersideoftheheatexchangertobereleased.Twoexamplesofthisareadiabaticwheels,whichconsistofalargewheelwithfinethreadsrotatingthroughthehotandcoldfluids,andfluidheatexchangers.Thistypeisusedwhenitisacceptableforasmallamountofmixingtooccurbetweenthetwostreams.Seealso:Airpreheater.RegenerativeheatexchangerAthirdtypeofheatexchangeristheregenerativeheatexchanger.Inthis,theheat(heatmedium)fromaprocessisusedtowarmthefluidstobeusedintheprocess,andthesametypeoffluidisusedeithersideoftheheatexchanger(theseheatexchangerscanbeeitherplate-and-frameorshell-and-tubeconstruction).Theseexchangersareusedonlyforgasesandnotforliquids.Themajorfactorforthisistheheatcapacityoftheheattransfermatrix.Alsosee:Countercurrentexchange,Regenerator,EconomizerPlateheatexchangerAnothertypeofheatexchangeristheplateheatexchanger.Oneiscomposedofmultiple,thin,slightly-separatedplatesthathaveverylargesurfaceareasandfluidflowpassagesforheattransfer.Thisstacked-platearrangementcanbemoreeffective,inagivenspace,thantheshellandtubeheatexchanger.Advancesingasketandbrazingtechnologyhavemadetheplate-typeheatexchangerincreasinglypractical.InHVACapplications,largeheatexchangersofthistypearecalledplate-and-frame;whenusedinopenloops,theseheatexchangersarenormallyofthegasketedtypetoallowperiodicdisassembly,cleaning,andinspection.Therearemanytypesofpermanently-bondedplateheatexchangers,suchasdip-brazedandvacuum-brazedplatevarieties,andtheyareoftenspecifiedforclosed-loopapplicationssuchasrefrigeration.Plateheatexchangersalsodifferinthetypesofplatesthatareused,andintheconfigurationsofthoseplates.Someplatesmaybestampedwithchevronorotherpatterns,whereothersmayhavemachinedfinsand/orgrooves.换热器的分类及其应用换热器是一种装置内置高效换热从一个中等至另一个，无论是媒体分隔了坚实的墙，使他们永远组合，或新闻媒体直接接触。1他们被广泛用于供暖，制冷，空调，发电厂，化肥厂，石化厂，炼油厂和天然气处理。换热器可分为根据其流安排。平行流换热器，两个流体进入换热器在同样的目的，和旅行中的彼此平行的另一边。在逆流换热器的液体进入热交换器从对面的目的。目前设计的柜台是最有效的，因为它可以转移最热热火（转让）的媒介。在横流式换热器，流体旅行大约垂直于一个通过热交换器。为了提高效率，热交换器的设计，最大限度地面积之间的墙壁两个流体，同时最大限度地减少阻力流体通过换热器。该交换机的性能也会受到影响，增加了鳍或波纹中的一个或两个方向，从而增加表面积和可能的渠道流体流动或诱使动荡。驾驶温度在传热表面不同位置，但一个适当的平均气温可界定。在最简单的系统，这是记录平均温差（对数平均温差）。有时直接了解对数平均温差不提供和台大方法是使用。相变式换热器典型釜沸用于工业蒸馏塔典型的水冷式表面冷凝器此外，加热或冷却液只是一个阶段，换热器可用于加热液体蒸发（或煮沸），或用作冷凝器冷却蒸汽和凝结为液体。在化工厂和炼油厂，reboilers用于热传入饲料蒸馏塔往往热交换器。蒸馏调校通常使用蒸馏冷凝器凝结成液态气体回。电厂有蒸汽驱动涡轮机普遍使用热交换器烧开水变成蒸汽。换热器或类似的单位生产的蒸汽水往往被称为锅炉或蒸汽发生器。在核电厂的要求压水式反应堆，特别是大型换热器通过热从小学（反应堆厂房）系统二级（蒸汽厂）系统，生产的水蒸汽的过程中，被称为蒸汽发生器。所有矿物燃料和核电厂使用蒸汽驱动涡轮机的表面冷凝器转换排汽从涡轮机到凝（水）的再利用。为了节约能源和冷却能力，化学和其他植物，蓄热式换热器可用于传热从一个流，需要冷却到另一个流，需要加热，如沸蒸馏冷却和饲料预热。这个词也可以指热交换器包含物质在其结构，有一个变化的阶段。这通常是固液相由于体积小，这些国家之间的区别。这种变化的阶段有效地作为一个缓冲区，因为它发生在一个恒定的温度，但仍允许换热接受额外的热量。一个例子在这个已被调查的是用于高功率电子设备的飞机。动态刮掉表面换热器另一种类型的换热器被称为“动态换热器”或“刮面式换热器”。这主要是用于加热或冷却的高粘度产品，结晶过程，蒸发和高污染的应用。长时间运行的时间达到由于连