Experimentswithmicro-ntubeinsinglephase

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1、InternationalJournalofRefrigeration27(2004)876–883www.elsevier.com/locate/ijrefrigExperimentswithmicro-fintubeinsinglephaseJacquelineBianconCopetti*,MarioHenriqueMacagnan,DaianadeSouza,RejaneDeCe´saroOliveskiDepartmentofMechanicalEngineering,SchoolofPhysicalandTechno

2、logicalSciences,UniversidadedoValedoRiodosSinos,Av.Unisinos,950Sa˜oLeopoldo,RS93022-000BrazilReceived4July2003;receivedinrevisedform30December2003;accepted2April2004AbstractThisworkshowsheattransferandfrictioncharacteristicsforwatersingle-phaseflowinmicro-fintubes.The

3、analysisofthermalandhydraulicbehaviorfromalaminartoaturbulentflowwascarriedoutinanexperimentalsetupwitha9.52mmdiametermicro-fintube.Thetubewaswrappedupwithanelectricalresistancetapetosupplyaconstantheatfluxtoitssurface.Differentoperationalconditionswereconsideredintheh

4、eatingtests.Theinletandoutlettemperatures,differentialwalltemperaturesalongthetube,pressuredropandflowrateweremeasured.Therelationshipsofheatfluxandflowratewithheattransfercoefficientandpressuredropwereanalyzed.Underthesameconditions,comparativeexperimentswithaninternal

5、lysmoothtubewereconducted.Themicro-fintubeprovideshigherheattransferperformancethanthesmoothtube(inturbulentflowhmicro-fin=hsmooth¼2:9).InspiteoftheincreaseinpressuredropðDpmicro-fin=Dpsmooth¼1:7Þtheheattransferresultsweresignificantlyhigher(about80%).Thisshowstheadvan

6、tagesofthisenhancedconfigurationinthermalperformancerelatedtoconventionaltubes.ThesmoothtuberesultswerevalidatedbythecomparisonwiththeDittus–BoelterandGnielinskicorrelations.Forthemicro-fintubeanempiricalcorrelationtotheheattransfercoefficientadjustedfromthesetofmeasur

7、eddataisproposed.Thevaluesobtainedareinconformitywithexperimentalresults.q2004ElsevierLtdandIIR.Allrightsreserved.Keywords:Experiment;Heattransfer;Pressuredrop;Flow;Water;FinnedtubeTubeamicroailetlesa`e´coulementmonophasique:expe´riencesMots-cle´s:Expe´rimentation;T

8、ransfertdechaleur;Chutedepression;Ecoulement;Eau;Tubeailete´1.Introductionsmalldiameterwereintroducedforthefirsttimeintheendofthe1970sbyHit