AppliedThermalEngineering36(2012)227e235

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AppliedThermalEngineering

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Theapplicationofentransydissipationtheoryinoptimizationdesignofheatexchangerq

JiangfengGuoa,MingtianXub,*

ab

InstituteofEngineeringThermophysics,ChineseAcademyofSciences,Beijing100190,PRChinaInstituteofThermalScienceandTechnology,ShandongUniversity,Jinan250061,PRChina

articleinfo

Articlehistory:

Received25January2011Accepted21December2011

Availableonline29December2011Keywords:

Entransydissipation

EntransydissipationnumberGeneticalgorithm(GA)OptimizationdesignHeatexchanger

abstract

Theoptimizationofheatexchangerdesignisinvestigatedbyapplyingtheentransydissipationtheoryandgeneticalgorithm.Itisfoundthattheroleplayedbythe uidfrictionisnotfullytakenintoaccountwhentheworking uidofheatexchangerisliquidinsingle-objectiveoptimizationapproach.Inordertocircumventthisproblem,amulti-objectiveoptimizationapproachtoheatexchangerdesignisestablished.

Ó2011ElsevierLtd.Allrightsreserved.

1.Introduction

Withthesharpdeclineoffossilfuelssuchaspetroleumandcoal,touseenergyef cientlyisoneofeffectivewaystofacetheincreasingenergydemand.Heatexchangerasanimportantdeviceinthermalsystemiswidelyappliedinpowerengineering,petro-leumre neries,chemicalindustries,andsoon.Hence,itisofgreatimportancetodeveloptechnologieswhichenableustoreducetheunnecessaryenergydissipationandimprovetheperformanceofheatexchanger.

Theevaluationcriteriaforheatexchangerperformancearegenerallyclassi edintotwogroups:the rstisbasedonthe rstlawofthermodynamics;thesecondisbasedonthecombinationofthe rstandsecondlawofthermodynamics.Theheattransferinheatexchangersusuallyinvolvestheheatconductionunder nitetemperaturedifference,the uidfrictionunder nitepressuredropand uidmixing.Theseprocessesarecharacterizedasirreversiblenon-equilibriumthermodynamicprocesses.Hence,inrecentdecadesthestudyofthesecondgrouphasattractedalotofattention[1].Inspiredbytheminimumentropyproductionprin-cipleadvancedbyPrigogine[2],Bejan[3,4]developedtheentropy

*Presentedatthe14thInternationalHeatTransferConference,Washington,DC,August8-13,2010.RepublishedwithpermissionfromAmericanSocietyofMechanicalEngineers(ASME).

*Correspondingauthor.Tel.:þ865319930006503;fax:þ8653188399598.E-mailaddress:mingtian@(M.

Xu).

generationminimization(EGM)approachtoheatexchangeropti-mizationdesign.Inthisapproach,Bejan[3]tookintoaccounttwotypesoftheirreversibilitiesinheatexchanger,namely,theheatconductionunderthestream-to-streamtemperaturedifferenceandthefrictionalpressuredropthataccompaniesthecirculationof uidthroughtheapparatus.Therefore,thetotalentropyproduc-_genisthesumofentropyproductionsasso-tionratedenotedbyS

ciatedwithheatconductionand uidfriction.However,amongallthevariationalprinciplesinthermodynamics,Prigogine’sminimumentropygenerationprincipleisstillthemostdebatedone[5].Accordingly,theentropygenerationminimizationapproach,widelyappliedtomodelingandoptimizationofthermalsystemsthatowetheirthermodynamicimperfectiontoheattransfer,masstransfer,and uid owirreversibilities,demonstratessomeinconsistenciesandparadoxesinapplicationsofheatexchangerdesigns[6].Thisisbecausethefocusoftheentropygenerationminimizationapproachisontheheat-workconversionprocesses,whileinheatexchangerdesignstherateandef ciencyofheattransferaremoreconcerned.Byanalogywiththeelectricalconduction,Guoetal.[7,8]de nedanewphysicalconcept,entransy,whichdescribestheheattransferability.Basedontheentransy,theheattransferef ciencycanbede nedandtheopti-mizationdesignofheatexchangercanbediscussed.Itisfoundthatintheirreversibleprocessestheentransyisdissipatedandtheheattransportcapabilityattenuates[9].Themoredissipationoftheentransyimpliesthehigherdegreeofirreversibilityinheattransfer

1359-4311/$eseefrontmatterÓ2011ElsevierLtd.Allrightsreserved.doi:10.1016/j.applthermaleng.2011.12.043