换热器的优化选型的中英文翻译.docx

换热器的优化选型的中英文翻译.docx

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换热器的优化选型的中英文翻译

附录一

NewplateheatexchangeroptimizationSelection

W.LubandS.A.Tassoub

DepartmentofMechanicalEngineering,SchoolofEngineeringandDesign,BrunelUniversity,Uxbridge,Middlesex,UK.

Abstract:

TheplateheatexchangerSelectionisbasedontheoptimizationoftheuseofheatexchangersandintheprocessoftheparametersandNTU=KA/MC=△t/△tm,thatis,transferunitsofNTUandthetemperaturedifferencethan（theaveragetemperaturedifference--Heattransferinpower）chooseplateshapes,plateheatexchangerandthetypeofstructure.

Keywords:

theaveragetemperaturedifferencebetweenNTUplateevaporatorcondenser

1averagetemperaturedifference△tm

　　Whentheheatexchangertoheat-dQ,whenthetemperaturerosetodt,C=dQ/dt,Cwillbedefinedasheatcapacity,itsaidunitsoftimethroughtheexchangeofheatperunitarea,dQ=K（th-tc）dA=K△tdA,twoofthefluidtemperaturechangesweredth=-dQ/Ch,dtc=-dQ/Cc,d△t=d（th-tc）=dQ（1/Cc-1/Ch）,whiledA=[1/k（1/Cc-1/Ch）]•（d△t/△t）,whentheA=0pointstoA=A0when,A0=[1/k（1/Cc-1/Ch）]•㏑[（tho-tci）/（thi-tco）],becauseoftwofluidexchangebetweentheheatequivalent,thatis,Q=Ch（thi-tho）=Cc（tco-tci）,thesimplifiedKnow,Q=KA0（[（tho-tci）-（thi-tco）]/㏑[（tho-tci）/（thi-tco）]）,if△t1=thi-tco,△t2=tho-tci,Q=KA0[（△t1-△t2）/㏑（△t1/△t2）]=KA0△tm,in-△tm=（△t1-△t2）/㏑（△t1/△t2）.

　　Down△tm=[（thi-tci）-（tho-tco）]/㏑[（thi-tci）/（tho-tci）]

　　Countercurrent△tm=[（thi-tco）-（tho-tci）]/㏑[（thi-tco）/（tho-tci）]

　　Forvariousflowpatternsinthesameimport,exportundertheconditionsoftemperature,theaveragetemperaturedifferencebetweenthelargestcounter-current.

　　Whentheplateheatexchangerimportandexportofthefluidtemperaturedifferencebetweenthetwo△t1andthedifferencebetween△t2notavailablewhenarithmeticaveragetemperature（△t1+△t2）/2,General△t1/△t2lessthan1.5,Maybe,if△t/△t2for3:

00,theerrorisabout10percent.

1.2thenumberoftransferunits

　　IntheheattransferunitoftheintroductionofafewdimensionlessparametersNTU,knownasthenumberoftransferunits,itsaidplateheatexchangerofthetotalthermalconductivity（heatexchangerheatresistanceofthecountdown）andtheratiooffluidheatcapacityNTU=KA/MC,itsaidinrelationtoheatfluidflow,heattransfercapacityoftheheatexchangerofthesizeoftheheatexchangerthatis,non-dimensional"heattransfercapability."Theplateheatexchangerfor,KA/MC=△t/△tm,where△t/△tmknownasthetemperaturedifferencethan,ontherightsideoftheprocessusedNTUpthatlefttheconditionsofheattransferequipmentusedNTUEsaid.NTUpisfluidtemperaturechangesintemperatureandtheaverageratiothatisused1℃△tmofseveralchangesinthevalueoffluidtemperaturechanges,when△tmlarge,NTUpissmallwhen△tmhours,ithasbecomebiggerThetendency.Onthecontrary,inNTUplargerintheprocess,△tmofthelargertemperaturechanges,NTUpsmaller,its△tmsmallchangesintemperature（seetable1）.

Table1△tm,NTUprelations

△tmlarge

△tmsmall

NTUpsmall

NTUplarge

NTUplarge

NTUpsmall

△tmlargechangesintemperature

△tmsmallchangesintemperature

　　Plateheatexchanger,theoptimaldesign,isknownNTUEtemperaturedifferencethantheconditions,todetermineareasonablemodel,processesandheattransferarea,equivalenttoNTUpNTUE.

1.3heattransferprocessandtheNTU

Heatingandair-conditioningrelatedtotheheattransferprocessiftheshowareasfollows:

⑴steamheatingwater⑵water-waterheatexchanger

a.steam133→133℃c.awater65→60℃

Water5→65℃（hotwater）Secondarywater45←40℃（heating）

b.Steam133→133℃d.awater14→9℃

Water55→65℃（heating）secondarywater13←7℃（refrigeration）

e.awater29→24℃

Secondarywater26←21℃（refrigeratorcooling）

　　MorethanfivecasesoftheprocessNTUp（seetable2）

Table2heatingair-conditioningprocessofNTUp

process

△tm

NTUp

a

133→133℃

5→65℃

94.86

（65－5）／94.86＝0.632

b

133→133℃

55→65℃

72.88

（65－55）／72.88＝0.13

c

65→60℃

45←40℃

20.00

（45－40）／20＝0.25

d

14→9℃

13←7℃

1.44

（13－7）／1.44＝4.17

e

29→24℃

26←21℃

3.00

（26－21）／3＝1.67

1.4plateheatexchangerandNTUE

　　NTUEplateheatexchangerthatthecapacityofheatexchangeristhesizeofacertainlengthoftheheatandthecombinationofheattransferunits,thetotallengthofheattransferprocessisthelengthandnumberofunitsoftheproduct.WhenthetotalnumberofNTUEis,ifthenumberofprocessesforevery1NTUe,thenNTUE=n•NTUe（wherenisthenumberofprocesses）.

　　WhenNTUe=NTUE=NTUp,theheatexchangerforone-way.IfNTUe

K=500,NTUe=NTUE/n=0.33,K=2500when,NTUe=1.67.So,canbeobtainedunderNTUetheflowofheatexchangers,heattransfercoefficientandheattransferarea.Fromtheabovewecanseethatiftheplateheatexchangerdesignunreasonableandlikelytoheattransferareaistoolarge,mayalsobepartitionedsothatflowistoohigh,toomuchresistance.

1.5plateheatexchangermanufacturingandtechnologicalprogress,platetypeofincrease,raisingtheplateheatexchangerofthevariousprocessesofadaptation.

　　⑴theNTU（∽8）,small△tm（∽1~2）theplateheatexchangertomeetthedistrictcoolingandheatpumpunitsevaporator,condenserrequirements.Fromtheaboveanalysisknow,△tmisthedrivingforceofheattransfer,if△tmsmall,meansthatthedriverofsmall,toachievetheheattransferbetweenthetwofluid,wemustincreaseheattransfercoefficient,increasingheattransferarea,inordertoHeattomakeuptoolarge,istheonlyincreaseheattransfercoefficientK.

①shallowplateofcorrugatedBeijing,Beijingistheheattransferequipmentmanufacturerslimitedliabilitycompanydevelopedanewtypeofplate,theheattransfercoefficientofabout7000W/㎡•K,istheleveloftheflatcorrugatedboardtwotimes,ischevronCorrugatedsheetsof1.5times,intheregionalcooling,thedetectionof△tmisabout1.2.Asinicestorageofethyleneglycolandchilledwateruseintheheatexchanger,△tmisabout1.5.

②plateevaporator,condenserplateBeijing,Beijingisalsotheheattransferequipmentmanufacturerslimitedliabilitycompaniesadapttothedevelopmentofanewtypeofheatpumpunitsintheheatexchanger.Andtheshell-and-evaporator,comparedtothecondenser,whichhasthefollowingadvantages:

unitvolumeintheevaporatorplate,theplatecondenserisaheattransferareaofshellandtubeheatexchangerofthreetimestheplateevaporatorheattransfercoefficientAbout1000~1200W/㎡•K,thecondenserplateheattransfercoefficientofabout1500~2000W/㎡•KareshellheatexchangertwotothreetimestheplateontheevaporatorusedtoRefrigerantdistributorofliquidevenlydistributeddevices,whentheevaporatorplateafewmore,maybeunevendistributionofliquidrefrigerantandcannottakefulladvantageofalltheheatandevaporationarea,evaporationtemperaturelowerthanthecalculateddesigntemperature.Afteradistributorovercometheseproblems.Detectionofdataontherelevantunits,evaporatorplate,theplatecondenserintheheattransfercoefficient△tmabout2.5~3℃,in1500~2000W/㎡•Kbetweentheresistanceandsmall,satisfyingtheheatpumpunitsRequirements.

⑵smallNTU（∽0.3~2）,the△tm（∽40~90℃）oftheplateheatexchangertomeettheheatrecoveryprocessandtheprocessheatingandcoolingrequirements.Whentheprocessinthe△tmconductedunderconditionsofheattransfer,thatdrivingforce,theheatandthesmaller,theheattransfercoefficientdemandisnothigh,butthatthisprocessorhigh-pressurework,orworkHightemperature,orprocessheatingandcoolingprocessintheliquidcontainingfiberdiameterorlargerparticles,theplateheatexchanger,thepressure,temperatureandabilitytorequest,theheatexchangertotheplatespacingrequirements.

①Pai（breathing）gas-watershellheatexchanger（Provincecan）,Pai（breathing）gas-shell-airheatexchangers（airpreheater）isaheatexchangerinBeijingBeijing-equipmentmanufacturerslimitedliabilityPortlandpetrochemicalcompaniesandco-developedanewtypeofplateheatexchanger,allweldedplateheatexchangerintheheattransferthroughthemediumtoachievethecontrolboard,composedofboardcontrolbytheplateforformingmoldsuppression,all-welded-Beaminstalledinthepressureshell.Corrugatedplatewithstaticmixing,inaverylowReynoldsnumberformedundertheturbulence,andlowcoefficientofdirt,theheattransfercoefficientistheshellandtubeheatexchangerofthetwoorthreetimes.Inordertoadapttotheheattransfer,fluidpressureontherequest,boardspace,equivalentdiameterofabout28mm.Inordertomeetthedemandsofworkpressureplatebeam（Anti-pressure）P≤4.5Mpa,thepressureplatebeam（pressure）withthepressureshell,unrestricted;temperaturet≤550℃.UrumqiPetrochemicalCompany400,000tons/yearforarestructuringofthefeed（coldmedium）anddischarg