CHFanddryoutpointinverticalnarrowannuliOriginalResearchArticle

ExperimentalstudyassociatedwithCHFanddryoutpointinnarrowannuliisconductedwith1.5mmand1.0mmgap,respectively.Distilledwaterisusedasworkfluid.Theparametersexaminedwere:pressurefrom2.0MPato4.0MPa;massfluxfrom26.0kg/(m2s)to69.0kg/(m2s);heatfluxfrom10kW/m2to70kW/m2;exitequilibriummassqualityfrom0.52to1.08. ItisfoundthatCHFmonotonouslyincreaseswithmassfluxininternallyheatedannuliandbilaterallyheatedannuli.However,theobservedtrendsarenotsimilartothatinexternallyheatedannuli.TheCHFisnotaffectedsignificantlybymassflux. Criticalqualitiesofdryoutpoint(XDO)decreaseswithmassfluxandincreaseswithinletqualities.UnderthesameconditionsXDOinoutertubearealwayslargerthanthatininnertube.Accordingtoexperimentaldata,acriterionfortheappearanceofdryoutpointforbilaterallyheatedhasbeenpresented. Thecomparisonwiththecorrelations[КУТАТЕЛАДЗЕ,C.C.,1979.Тедплоэнергетика,No.6]andexperimentaldataindicatesthattheexistingcorrelationsappliedtotubecannotpredictXDOinnarrowannuliwell.Basedonexperimentaldata,anewcorrelationisdeveloped.