MODELING OF INTERFACIAL SHEAR FOR GAS-LIQUID FLOWS IN ANNULAR FILM CONDENSATION

Internal flow of pure vapor experiencing film condensation on the wall s of a straight horizontal duct is studied. The commonly occurring ann ular case of turbulent (or laminar) vapor flow in the core and laminar flow of the liquid condensate-with or without waves on the interface- is emphasized. We present a new methodology which models interfacial s hear with the help of theory, computations, and reliable experimental data on heat transfer rates. The theory-at the point of onset of conde nsation-deals with issues of asymptotic form of interfacial shear, non uniqueness of solutions, and selection of the physically admissible so lution by a stability type criteria. Other details of the flow are pre dicted with the help of the proposed modeling approach. These predicti ons are shown to be in agreement with relevant experimental data. The trends for film thickness, heat transfer rates, and pressure drops are also made available in the form of power-law correlations.