螺纹管内单相流动换热与污垢沉积的数值分析与优化设计

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1、万方数据AbstractRecently,internalhelicallyribbedtubebecomesoneofthemostwidelyusedpassiveheattransferenhancementtechnique，becauseofitseffectiveheattransfereffect，lowpressuredroplossandlowcostofmassproduction．Andfoulinginenhancedheattransferexchangersisaninen

2、vitableandcomplexproblem，whichhasmanyinfluentialfactors，SOmorcandmoreinvestigationsareneededinthedetailresearchesofheattransferandfoulingperformance．Frommassbalanceintheinvestigation，thispaperusesVon—Karmananalogytopredictthefoulingperformanceandnumeric

3、allystudytheeffectonheattransferenhancementandfoulingofeachmainparameterinhelicallyfibbedtubes，whichCanbeusedtooptimizethedesignofhelicallyribbedtubegenerallyandbroadenitsfurtherapplications．Resultsareasfollows：(1)Thenumericalanalysisofheattransferandpr

4、essuredropforturbulentflowineighthelicallyribbedtubeswith15．54mminsidediameterhasbeenperformed．Theturbulentmodelisselectedcarefullyandtheeffectof鲥dindependenceisextensivelyexamined．Thecomputationalresultsmatchwellwiththeexperimentaldatatovalidatetheaccu

5、racyofthenumericalmodel．(2)ThefoulingmodelisestablishedbasedonKern—SeatonmassbalancemodelandVon-Karmananalogy．Combinedwithnumericalmodel，heattransfereffectandfoulingperformanceonthehelicalsurfacecallbeobtained．Bycomparingtheresultswithexperimentalfoulin

6、gdata,theinvestigationmethodthepaperusedisright．(3)Theeffectofeachmainparameter：ribshape，ribstarts，helixangle，andribheight，onheattransferandpressuredropisinvestigated．Everyparameterhasbeenanalyzedandcomparedbyenhancementfactor，7’carefully,SOthatwecansel

7、ecttheoptimumgeometry：ribshapeofrectangle，trapezoidandtrianglewithsmallincluededanglearebetterthanothershapes；ribstartsisbetteraroud50andhelixangleisbestat25。-35。；ribheightlookslikethehigherthebetter．(4)Consideringfoulinginpracticalsituation，theratioofp

8、itchoverribheightisanimportantparametertoselectthetubes．ItisadvisabletoselectthetubeswithpitchOVerrib111万方数据heightratiogreaterthan3．5，whichhavebetterheattransferandlowerfoulingpotential．Therefore，whenribstartsis50andhelixangleis2