Two-phaseflowandboilingheattransferintwoverticalnarrowannuliOriginalResearchArticle

Experimentalstudyassociatedwithtwo-phaseflowandheattransferduringflowboilingintwoverticalnarrowannulihasbeenconducted.Theparametersexaminedwere:massfluxfrom38.8to163.1kg/m2s;heatfluxfrom4.9to50.7kW/m2forinsidetubeandfrom4.2to78.8kW/m2foroutsidetube;equilibriummassqualityfrom0.02to0.88;systempressurefrom1.5to6.0MPa.Itwasfoundthattheboilingheattransferwasstronglyinfluencedbyheatflux,whiletheeffectofmassvelocityandmassqualitywerenotverysignificant.Thissuggestedthattheboilingheattransferwasmainlyvianucleateboiling.Thedatawereusedtodevelopanewcorrelationforboilingheattransferinthenarrowannuli.Inthetwo-phaseflowstudy,thecomparisonwiththecorrelationofChisholm[Chisholm,D.,1967.AtheoreticalbasisfortheLockhart–Martinellicorrelationfortwo-phaseflow.Int.J.HeatMassTransfer10,1767–1778]andMishimaandHibiki[Mishima,K.,Hibiki,T.,1996.Somecharacteristicsofair–watertwo-phaseflowinsmalldiameterverticaltubes.Int.J.MultiphaseFlow22,703–712]indicatedthattheexistingcorrelationscouldnotpredictthetwo-phasemultiplierinthenarrowannuliwell.Basedontheexperimentaldata,anewcorrelationwasdeveloped.