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1、Inr.J.HealMossTransfer.Vol.34,No.11,pp.2827-2831,19910017-9310/9153.00+0.00PrintedmGreatBritain@?1991PergamonPressplcAstudyonthemechanismofdropwisecondensationYONGJISONG,DUNQIXUandJIFANGLINDepartmentofChemicalEngineering,DalianUniversityofTechnology,Dalian116012,ChinaandSIEXONGTSIA
2、NDepartmentofPhysics,FudanUniversity,Shanghai,China(Received21August1990andin$nalform10December1990)Abstract-Fromthebasicviewpointofadsorptiontheory,themechanismoftheformationofdropletsduringdropwisecondensationisanalysed.Itisproposedthatathinfilmofcondensateexistsontheareaamongthe
3、dropletsandalsoafilmofcondensatestillexistsatthespotsfromwhichthedropletsdeparted.Consequently,amechanismofthedropwisecondensation(dropletsandfilmcoexisting(DFC))ispresented.Withthecomputerizedthinfilmthicknessmeasurementtechnology,themechanismisproved.INTRODUCTIONfaceandsomemolecu
4、leswillcondenseuponthesur-faceofasolid.ThesurfacewhichisexposedtotheTHEHIGHheattransfercoefficientsofdropwisecon-gasorvapourcanadsorbthemeverywhere.Asfordensationaregenerallyaccepted,butthemechanismthephysicaladsorption[5],heatwillbegivenupdur-ofthisphenomenonhas,notsurprisingly,gi
5、venriseingtheadsorptionprocess.Therefore,equilibriumtoavarietyofsuggestions.adsorptivityofthegasorvapouronthesurfacewillTherearetwocompletelydifferentviewpointsincreaseatdecreasedtemperatureofthesurface.aboutthemechanismoftheformationofdropletsPhysicaladsorptioncanbemonolayeradsorp
6、tionorduringdropwisecondensation.Oneideathatathinmultilayeradsorption.Inmultilayeradsorption,theunstablefilmfirstappearsonthenewlyexposedareaadsorptiveheatofacertainlayerislessthanthenextandsubsequentlybreaksupintodroplets,waspro-oneaboveit,andthemorelayers,themoretheposedbyJakob[l
7、].liquifyingheatofthegas,orvapour,atthispressureTheotherideathatthedropsappeartohavetheisapproached.Therefore,thecondensationprocessessamearrangementonthesurfaceandtheexistenceofgenerallyoccurintheconditionofthelimitationofparticularnucleationsitesoccursonthesurface,wasphysicaladso
8、rptionprocesses.proposedby