One-dimensionalcriticalheatfluxconcerningsurfaceorientationandgapsizeeffectsOriginalResearchArticle

Testswereconductedtoexaminethecriticalheatflux(CHF)onaone-dimensionaldownwardheatingrectangularchannelhavinganarrowgapbychangingtheorientationofthecoppertestheaterassemblyinapoolofsaturatedwaterunderatmosphericpressure.Thetestparametersincludeboththegapsizesof1,2,5and10mm,andthesurfaceorientationanglesfromthedownward-facingposition(180°)totheverticalposition(90°),respectively.Also,theCHFexperimentswereperformedforpoolboilingwithvaryingheatersurfaceorientationsintheunconfinedspaceatatmosphericpressureusingtherectangulartestsection.ItwasobservedthattheCHFgenerallydecreasesasthesurfaceinclinationangleincreasesandasthegapsizedecreases.Inconsistencywithseveralstudiesreportedintheliterature,itwasfoundthatthereexistsatransitionangleatwhichtheCHFchangeswitharapidslope.AnengineeringcorrelationisdevelopedfortheCHFduringnaturalconvectiveboilingintheinclined,confinedrectangularchannelswiththeaidofdimensionalanalysis.Thiscorrelationagreeswiththeexperimentaldataofthisstudywithin±20%.