简介：

简介：

简介：Thelocalpressuredistributionsandresistancecoefficients(f1andf2)throughthesharp180degturninarelativelyshort(L/De=4)two-passsmoothandrib-roughenedchannelwereinvestigatedforaReynoldsnumberrangeof1.0×10^3,9.0×10^3.Theribpitch-to-herghtratios(p/e)were5,10,and20,Theribheight-to-hydraulicdiamterratios(e/De)were0.025,0.050and0.10,andtheribanglesofattack(a)were90,45,60,-45,and-60deg.Ridswereinstallednotonlyinbeforeandafterturnregionsbutalsointurnregion.TheresultsshowthatresistancecoefficientsremainapproximatelyconstantwhenReynoldsnumberismorethan3.0×10^4,Theeffectsoftheribconfiguration(ribspacing,ribheight,andriborientation)ontheinletstraightductresistancecoefficient(f2)weresignificant,however,theireffectsontheoverallresistancecoefficient(f1)weredilutedbythesharp-180turn.Forthisrelativelyshortchannel(L/De=4),theoverallresistancecoefficient(f1)wasgreatlyaffectedbythesharpturn.Correlationsfortheoverallresistance(f1)andinletstraightductresistancecoefficient(f2)arepresented.

简介：Amechanismisproposedfornucleatepoolboilingheattransferalongwithageneralmodelforbothpureliquidsandbinarymixtrues.Acombinedphysicalmodelofbubblegrowthisalsoproposedalongwithacorrespondingbubblegrowthmodelforpureliquidsonsmoothtubes.Usingthegeneralmodelandthebubblegrowthmodelforpureliquids,ananalyticaslmodelfornucleatepoolboilingheattransferofpureliquidsonsmoothtubesisdeveloped.

简介：Acombinedphysicalmodelofbubbelgrowthispropsedalongwithacorrespondingbubblegrowthmodelforbinarymixturesonsmoothtubes.UsingthegeneralmodelofWangetal.^[1].andthebubblegrowthmodelforbinarymixtures,ananalyticalmodelfornucleatepoolboilingheattransferofbinarymixturesonsmoothtubesisdeveloped.Inaddition,nucleatepoolboilingheattransferofpureliquidsandbinarymixtruesonahorizontalsmoothtubewasstudiedexperimentally.Thepureliquidsandbinarymixturesincludedwatermethanol,ehanol,andtheirbinarymixtures.Theanalyticalmodelsforbothpureliquidsandbinarymixturesareingoodagreementwiththeexperimentaldata.