Modeling of condensation in steam-water stratified flow based on convective heat transfer

Abstract

This paper presents a model of direct contact condensation in steam-water stratified flow. It is based on convective heat transfer in the liquid film (CHT model). The analytical form of a model makes the use suitable within one-dimensional two-fluid models as a closure law. Validity of CHT model is demonstrated by the simulation of Bankoff's and Lee's (1987) experiments of complex steam-water counter-current flow with condensation, as well as the simulation of Celata's et al. (1989) experiments of the stagnant steam condensation on turbulent and laminar subcooled liquid films. The two-fluid model predictions with CHT model show excellent agreement with the measured data. Both liquid film and steam flow parameters, such as the condensation rate, steam flow rate, liquid film thickness and change in temperature, are accurately predicted in case of counter-current flow, despite the presence of wavy interface and intensive interfacial mass and momentum transfer. In case of stagnant steam condensation, the influence of laminar and turbulent flow conditions, as well as a liquid film level change to the rate of condensation is clearly demonstrated. In order to obtain an insight in liquid film velocity and temperature distributions, here is applied a 2D parabolic model of liquid film flow. Also, discussed are possibilities of the 1D and 2D approaches to incorporate the dependence of the condensation rate upon turbulent effects in the liquid film.