Microcomputer-enhanced optical investigation of transport processes with phase change in near-equilibrium thin liquid films.pdf

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1、Microcomputer-EnhancedOpticalInvestigationofTransportProcesseswithPhaseChangeinNear-EquilibriumThinLiquidFilmsMANOJSUJANANIANDPETERC.WAYNER,JR.1TheIsermannDepartmentofChemicalEngineering,RensselaerPolytechnicInstitute,Troy,NewYork12180-3590ReceivedJuly27,1990;acceptedOctober25,1990Thenear-equil

2、ibriumthicknessprofilesofanextendedmeniscusinthecontactlineregionofacom-pletelywettingfilmofoctaneonaninclined,flatplateweremeasuredusinganellipsometerandamicrocomputer-enhancedinterferometer.Theextremesensitivityofthesystemtothenonequilibriumeffectsassociatedwithvolatileliquidsisdemonstratedan

3、devaluated.Theinferredequilibriumprofileagreedwiththeoreticalpredictionsofthewidthofthetransitionregion,thecurvature,andthethicknessoftheadsorbedfilm.Theproceduresallowtheinterfacialpropertiesofthesystemtobeevaluatedinsituatthestartofdynamicstudiesandthentobeusedtodescribethetransportprocessesa

4、ssociatedwithevaporationandcondensation.Theeffectoftransportprocessesonthethicknessprofileagreedwithprevioustheoreticalmodels.Theconvenienceofmicrocomputer-enhancedvideomicroscopynat-urallyleadstoabetterunderstandingofthetransportprocessesinthecontactlineregion.Theresultsdemonstratethatthenear-

5、equilibriumprocessesofchange-of-phaseheattransferandfluidflowinthinfilmsareintrinsicallyconnectedbecauseoftheircommondependenceontheintermolecularforcefieldandgravity.©1991AcademicPress,Inc.INTRODUCTIONandtheregion'sextremesensitivitytocon-taminationandnonisothermaleffects,factorsWhenacompletel

6、ywettingliquidfilmwhicharedifficulttoincludeintheoreticalspreadsonasolidsubstrateacontactlinere-analysesandwhichmayvarygreatlyfromonegionisformedwherethevapor,liquid,andexperimentalstudytoanother.solid(withanadsorbedfilmofvapor)phasesConsiderFig.1whichrepresentsaninclinedareincloseproximity.The

7、transportprocessessiliconplateimmersedinaliquidatanangleandinterfacialphenomenaoccurringinthis0tothehorizontal.Theplateisinaclosedcellmicroscopicregion[width~0(10-3m);andaspreadingliquid,inequilibriumwithitsthickness6<10-5m]arecon