一种新型扭带对管内对流换热影响的研究

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1、万方数据一种新型纽带对管内对流传热影响的研究ThestudyontheheattransfercharacteristicsintubewithanewkindoftwistedtapeinsertAbstractHeattransferenhancementintubeiSvalidlyusedinmanytechnologyregions．Asapassiveheattrans；ferenhancementtechnology．twistedtapeiSasimpleandeffectivemethod．Twistedtapecanchanget1

2、1echanneloftheflow．reducethethicknessoftheboundarylayer．andthenenhanceheattransfer．However．twistedtapeCanalSOincreasethefrictionfactor．Asaresult、tobalancetheNesseltnumberandfrictionfactorandmaintainhigherPEC．themainemphasisiSputonthemodificationoftheshapesoftwistedtapes．Anewkind

3、oftwistedtape(TTC)wasintroducedinthisPaDer．NumericalsimulationandexperimentalresearchwasperformedtOstudytheeffectonheattransferandfrictionfactorcharacteristicsinatubewiththisnewkindoftwistedtapesinsert．Inthenumericalstudy．uniformwalltemperaturewasusedasthethermalboundaryconditio

4、nsforbothlaminarflowandturbulentflow．Otherwise．theresultswerecomparedwithtwistedtapewithoutcurve(TT)intheperipheryregion．TheresultsshowedthattheNuandfrictionfactorinthetubefittedwithTTCwere1．18．1．50and2．65．3．22timesofthatfortheplainttubeinturbulentflowconditions，respectively．The

5、ratioofMtoMnreducedwiththeincreaseofReynoldsnumber．whichindicatedthatTTCperformedbeUerinweakturbulentflowconditions．ThePECforTTCWas1．86．1．02．whichwas1．09．1．17timesofthatforTT．Inlaminarflowconditions．thePECinthetubefixedwithTTCwere1．34．1．78and1．05·1．13timesofthatfortheplainttubea

6、ndTT．respectively．ItCanbeseenthatTTCperformedbeRerthanTTbothinlaminarflowandturbulentflow。Asaresult．TTCwasrecommendedfromtheviewofheattransferemciencyandmaterialsaving．Forthelimitationofexperimentalsystem．onlyturbulentflowconditionswerestudiedintheexperimentalstudy．Fourtwistedta

7、peswithdifferentlengthwereusedintheexperimentalstudy．TheexperimentaldatarevealedthatNuincreasewiththeincreaseofRe．A1lthesefourtwistedtapesCancausehigherNuthantheplaintube．Thetwistedtapesalsocausehigherfrictionfactor，especiallyfor朋=1．0and0．75，withthevalueof3．69—5．75and2．30．4．48．r

8、espectively．The尸ECforL／l=1．0，0．75，0．50andO．25iS