Numerical simulation of methane condensation in the presence of nitrogen

Abstract

A numerical model was built to calculate methane condensation on isothermal vertical plate with nitrogen existed as a non-condensable gas. A volume of fluid (VOF) method based on Eulerian multiphase models was used to trace liquid-gas interface. Mass and energy source terms during condensation at the liquid-gas interface were calculated with a user defined function (UDF) based on mass conservation. Nitrogen mass fractions of 0%, 0.869%, 1.733%, 3.441%, 8.417%, 11.616% and 16.249%, and wall subcooled temperatures of 5 K, 10 K, 15 K and 20 K were considered in this study. The results show that the presence of nitrogen significantly reduces heat transfer coefficient of methane condensation. When the nitrogen mass fraction is 3.441%, the heat transfer coefficient declines by ~70% compared with pure methane at wall subcooled temperature of 10 K. The liquid film thickness is two orders of magnitude thinner than that of the gas boundary layer. The main resistance of heat transfer is the diffusive resistance of the vapor-gas mixture.