热泵的应用外文翻译secret.docx
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热泵的应用外文翻译secret
外文翻译
TheApplicationsofHeatpumps
1.Heatpumpsinindustry
1).Systems
Relativelyfewheatpumpsarecurrentlyinstalledinindustry.However,asenvironmentalregulationsbecomestricter,industrialheatpumpscanbecomeanimportanttechnologytoreduceemissions,improveefficiency,andlimittheuseofgroundwaterforcooling
Toensurethesoundapplicationofheatpumpsinindustry,processesshouldbeoptimisedandintegrated.Throughprocessintegrationimprovedenergyefficiencyisachievedbythermodynamicallyoptimisingtotalindustrialprocesses.Animportantinstrumentforprocessintegrationispinchanalysis,atechnologytocharacteriseprocessheatstreamsandidentifypossibilitiesforheatrecovery.Suchpossibilitiesmayincludeimprovedheatexchangernetworks,cogenerationandheatpumps.Pinchanalysisisespeciallypowerfulforlarge,complexprocesseswithmultipleoperations,andisanexcellentinstrumenttoidentifysoundheatpumpopportunities.
Industrialapplicationsshowagreatvariationinthetypeofdriveenergy,heatpumpsize,operatingconditions,heatsourcesandthetypeofapplication.Theheatpumpunitsaregenerallydesignedforaspecificapplication,andarethereforeunique.
Themajortypesofindustrialheatpumpsare:
oMechanicalvapourrecompressionsystems(MVRs),classifiedasopenorsemi-openheatpumps.Inopensystems,vapourfromanindustrialprocessiscompressedtoahigherpressureandthusahighertemperature,andcondensedinthesameprocessgivingoffheat.Insemi-opensystems,heat
fromtherecompressedvapouristransferredtotheprocessviaaheatexchanger.Becauseoneortwoheatexchangersareeliminated(evaporatorand/orcondenser)andthetemperatureliftisgenerallysmall,theperformanceofMVRsystemsishigh,withtypicalcoefficientsofperformance(COPs)of10to30.CurrentMVRsystemsworkwithheat-sourcetemperaturesfrom70-80篊,anddeliverheatbetween110and150篊,insomecasesupto200篊.Wateristhemostcommon'workingfluid'(i.e.recompressedprocessvapour),althoughotherprocessvapoursarealsoused,notablyinthe(petro-)chemicalindustry.
oClosed-cyclecompressionheatpumpsaredescribedinthesectionHeatpumptechnology.Currentlyappliedworkingfluidslimitthemaximumoutputtemperatureto120篊.
oAbsorptionheatpumps(TypeI)arenotwidelyusedinindustrialapplications.Somehavebeenrealisedtorecoverheatfromrefuseincinerationplants,notablyinSwedenandDenmark.Currentsystemswithwater/lithiumbromideasworkingpairachieveanoutputtemperatureof100篊andatemperatureliftof65篊.TheCOPtypicallyrangesfrom1.2to1.4.Thenewgenerationofadvancedabsorptionheatpumpsystemswillhavehigheroutputtemperatures(upto260篊)andhighertemperaturelifts.
oHeattransformers(TypeII)havethesamemaincomponentsandworkingprincipleasabsorptionheatpumps.Withaheattransformerwasteheatcanbeupgraded,virtuallywithouttheuseofexternaldriveenergy.Wasteheatofamediumtemperature(i.e.betweenthedemandlevelandtheenvironmentallevel)issuppliedtotheevaporatorandgenerator.Usefulheatofahighertemperatureisgivenoffintheabsorber.Allcurrentsystemsusewaterandlithiumbromideasworkingpair.Theseheattransformerscanachieveadeliverytemperaturesupto150篊,typicallywithaliftof50篊.COPsundertheseconditionsrangefrom0.45to0.48.
o
ReverseBrayton-cycleheatpumpsrecoversolventsfromgasesinmanyprocesses.Solventloadenairiscompressed,andthenexpanded.Theaircoolsthroughtheexpansion,andthesolventscondenseandarerecovered.Furtherexpansion(withtheassociatedadditionalcooling,condensationandsolventrecovery)takesplaceinaturbine,whichdrivesthecompressor.
2).Applications
Industrialheatpumpsaremainlyusedfor:
ospaceheating;
oheatingandcoolingofprocessstreams;
owaterheatingforwashing,sanitationandcleaning;
osteamproduction;
odrying/dehumidification;
oevaporation;
odistillation;
oconcentration.
Whenheatpumpsareusedindrying,evaporationanddistillationprocesses,heatisrecycledwithintheprocess.Forspaceheating,heatingofprocessstreamsandsteamproduction,heatpumpsutilise(waste)heatsourcesbetween20篊and100篊.
Themostcommonwasteheatstreamsinindustryarecoolingwater,effluent,condensate,moisture,andcondenserheatfromrefrigerationplants.Becauseofthefluctuationinwasteheatsupply,itcanbenecessarytouselargestoragetanksforaccumulationtoensurestableoperationoftheheatpump.
oSpaceheating:
Heatpumpscanutiliseconventionalheatsourcesforheatingofgreenhousesandindustrialbuildings,ortheycanrecoverindustrialwasteheatthatcould
notbeuseddirectly,andprovidealow-tomediumtemperatureheatthatcanbeutilisedinternallyorexternallyforspaceheating.Mainlyelectricclosed-cyclecompressionheatpumpsareused.
oProcesswaterheatingandcooling:
Manyindustriesneedwarmprocesswaterinthetemperaturerangefrom40-90篊,andoftenhaveasignificanthotwaterdemandinthesametemperaturerangeforwashing,sanitationandcleaningpurposes.Thiscanbemetbyheatpumps.Heatpumpscanalsobeapartofanintegratedsystemthatprovidesbothcoolingandheating.Mainlyelectricclosed-cyclecompressionheatpumpsareinstalled,butafewabsorptionheatpumpsandheattransformersarealsoinuse.
oSteamproduction:
Industryconsumesvastamountsoflow-,medium-andhigh-pressuresteaminthetemperaturerangefrom100-200篊.Steamisuseddirectlyinindustrialprocesses,andforheatdistribution.Currenthightemperatureheatpumpscanproducesteamupto150篊(aheatpumpprototypehasachieved300篊).Bothopenandsemi-openMVRsystems,closed-cyclecompressionheatpumps,cascade(combination)systemsandafewheattransformersareinoperation.
oDryingprocess:
Heatpumpsareusedextensivelyinindustrialdehumidificationanddryingprocessesatlowandmoderatetemperatures(maximum100篊).Themainapplicationsaredryingofpulpandpaper,variousfoodproductswoodandlumber.Dryingoftemperature-sensitiveproductsisalsointeresting.Heatpumpdryersgenerallyhavehighperformance(COP5-7),andoftenimprovethequalityofthedriedproductsascomparedwithtraditionaldryingmethods.Becausethedryingisexecutedinaclosedsystem,odoursfromthedryingoffoodproductsetc.arereduced.Bothclosed-cycle
compressionheatpumpsandMVRsystemsareused.
oEvaporationanddistillationprocesses:
Evaporationanddistillationareenergy-intensiveprocesses,andmostheatpumpsareinstalledintheseprocessesinthechemicalandfoodindustries.Inevaporationprocessestheresidueisthemainproduct,whilethevapour(distillate)isthemainproductindistillationprocesses.Mostsystemsareopenorsemi-openMVRs,butclosed-cyclecompressionheatpumpsarealsoapplied.SmalltemperatureliftsresultinhighperformancewithCOPsrangingfrom6to30.
2.Heatpumpsinresidentialandcommercialbuildings
1).Functions
Heatpumpsforheatingandcoolingbuildingscanbedividedintofourmaincategoriesdependingontheiroperationalfunction:
oHeating-onlyheatpumps,providingspaceheatingand/orwaterheating.
oHeatingandcoolingheatpumps,providingbothspaceheatingandcooling.
Themostcommontypeisthereversibleair-to-airheatpump,whicheitheroperatesinheatingorcoolingmode.Largeheatpumpsincommercial/institutionalbuildingsusewaterloops(hydronic)forheatandcolddistribution,sotheycanprovideheatingandcoolingsimultaneously.
oIntegratedheatpumpsystems,providingspaceheating,cooling,waterheatingandsometimesexhaustairheatrecovery.
Waterheatingcanbebydesuperheatingonly,orbydesuperheatingand
condenserheating.Thelatterpermitswaterheatingwhennospaceheatingorcoolingisrequired.
oHeatpumpwaterheaters,fullydedicatedtowaterheating.
Theyoftenuseairfromtheimmediatesurroundingsasheatsource,butcanalsobeexhaust-airheatpumps,ordesuperheatersonair-to-airandwater-to-airheatpumps.Heatpumpscanbebothmonovalentandbivalent,wheremonovalentheatpumpsmeettheannualheatingandcoolingdemandalone,whilebivalentheatpumpsaresizedfor20-60%ofthemaximumheatloadandmeetaround50-95%oftheannualheatingdemand(inaEuropeanresidence).Thepeakloadismetbyanauxiliaryheatingsystem,oftenagasoroilboiler.Inlargerbuildingstheheatpumpmaybeusedintandemwithacogenerationsystem(CHP).
Inresidentialapplicationsroomheatpumpscanbereversibleair-to-airheatpumps(ductlesspackagedorsplittypeunits).Theheatpumpcanalsobeintegratedinaforced-airductsystemorahydronicheatdistributionsystemwithfloorheatingorradiators(centralsystem).
Incommercial/institutionalbuildingstheheatpumpsystemcanbeacentralinstallationconnectedtoanairductorhydronicsystem,oramulti-zonesystemwheremultipleheatpumpunitsareplacedindifferentzonesofthebuildingtoprovideindividualspaceconditioning.Efficientinlargebuildingsisthewater-loopheatpumpsystem,whichinvolvesaclosedwaterloopwithmultipleheatpumpslinkedtothelooptoprovideheatingandcooling,withacoolingtowerandauxiliaryheatsourceasbackup.
ThedifferentheatsourcesthatcanbeusedforheatpumpsinresidentialandcommercialbuildingsaredescribedinthesectionHeatsources.Thenextparagraphdescribesthetypesofheatandcolddistributionsystemsthatcanbeusedinbuildings.
2).Heatandcolddistributionsystems
Airisthemostcommondistributionmediuminthematureheatpump