Effect of non-condensable gas on convective condensation on a short vertical plate

The effect of mass fraction of non-condensable air, liquid film and velocity of air-vapor mixture on the convective condensation on a short vertical plate was investigated numerically. The volume of fluid (VOF) was applied to model the two-phase flow of liquid film and gases mixture. The species transport between water vapor and air was calculated by the conservation equation for species. A modified phase change model, derived from basic equations related to the kinetic gas theory, was proposed and verified by two different cases. It was found that a small amount of non-condensable gas shows no significant effect on the convective condensation of water vapor. However, the heat transfer coefficient of convective condensation shrinks obviously as air concentration increases. And the heat transfer coefficient is about 8% higher than that of not ignoring liquid film. The heat transfer coefficient of convective condensation improves by increasing inlet velocity of the gas mixture to a lower extent than pure water vapor convection.