Conjugate thermosolutal convection and condensation of humid air in cavities

Abstract

Heat transfer by natural convection and surface condensation in two-dimensional enclosures in contact with a cold external ambient through a wall of finite thickness was studied numerically. Special attention was given on the modeling of the flow of a binary mixture consisting of humid air. Low-Mach number assumption was introduced in order to account for decreases in mixture mass and average pressure within the enclosure between the initial and steady states. The computations show that thermodynamic balances are satisfied within the accuracy of the numerical procedure. The heat and fluid flows with and without condensation are compared for various operating conditions. It is shown that vapor condensation increases the heat transfer rate at the cold wall at the early stage of the transient regime. The decrease in the average density of the mixture leads to significant variable's reductions at steady-state which, in turn, causes lower overall heat transfer rate than for dry air.