Volume of Fluid (VOF) Modeling of Liquid Film Evaporation in Mixed Convection Flow through a Vertical Channel

In this paper, the volume of fluid (VOF) method in the OpenFOAM open-source computational fluid dynamics (CFD) package is used to investigate the coupled heat and mass transfer by mixed convection during the evaporation of water-thin film. The liquid film is falling down on the left wall of a vertical channel and is subjected to a uniform heat flux density, whereas the right wall is assumed to be insulated and dry. The gas mixture consists of air and water vapor. The governing equations in the liquid and in the gas areas with the boundary conditions are solved by using the finite volume method. The results which include temperature, velocity, and vapor mass fraction are presented. The effect of heat flux density, liquid inlet temperature, and mass flow rate on the heat and mass transfer are also analyzed. Better liquid film evaporation is noted for the system with a higher heat flux density and inlet liquid temperature or a lower mass flow rate. Therefore, the VOF method describes well the thermal and dynamic behavior during the evaporation of the liquid film.