Title of article
Predictionoftheobstacleeffectonfilm-boilingheattransferOriginalResearchArticle
Author/Authors
L.K.H.Leung، نويسنده , , D.C.Groeneveld، نويسنده , , J.Zhang، نويسنده ,
Issue Information
روزنامه با شماره پیاپی سال 2005
Pages
14
From page
687
To page
700
Abstract
Acorrelationhasbeendevelopedtoaccountfortheeffectofobstacles(simulatingthespacingdevicesinbundles)onheattransferindispersed-flowfilmboiling.Thecorrelationisexpressedasamodificationfactortothereferencegeometrywithoutanyobstacles.Thebasicformofthecorrelationisanexponentialdecayfunctionthatresemblesthediminishingeffectonturbulenceenhancement.Thecoefficientsandconstantsinthecorrelationhavebeenoptimizedwithheat-transferdataoflow-pressuresingle-phase(air)flowandhigh-pressuresteam-waterflowatfilm-boilingconditions.
Anexperimenthasbeensetuptoobtainvalidationdatawithaheatedtubeof4.1mminsidediameter.HFC-134awasusedastheworkingfluid.Threetypesofobstacleswiththesameblockage-arearatioof37.8%weretested.Theresultsshowedthattheobstaclesexhibitedastrongenhancementeffectonthefilm-boilingheat-transfercoefficientatlocationsdownstreamoftheobstacles.Acomparisonbetweenpredictionsofthecorrelationforthespacing-deviceeffectandexperimentaldatashowedanunderpredictionoftheheat-transferrateatlocationsdownstreamoftheobstacle.Theunderpredictionisduemainlytotherewettingoftheheatedsurfaceatthelocationofanobstacle,beyondwhichthedevelopingfilm-boilingeffectbecomesdominant.Theagreementbetweenpredictionanddataissignificantlyimprovedafteraccountingforthecriticalheatflux(CHF)enhancementanddevelopingfilm-boilingeffectsinthecalculations.
Journal title
Nuclear Engineering and Design Eslah
Serial Year
2005
Journal title
Nuclear Engineering and Design Eslah
Record number
894879
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