Turbulent film condensation in a vertical tube in presence of non condensable gas

Abstract

This paper presents the simulation of the condensation of methanol vapour in the presence of non-condensable gas in turbulent flows in a vertical tube. The liquid and gas stream are approached by two coupled turbulent boundary layer. For solving the coupled governing equations for liquid film and gas flow together with the interfacial matching conditions an implicit finite difference method is employed. The effect of the influencing parameters are studied so the effect of inlet Reynolds number, the effect of temperature gradient, mass fraction are illustrated. The numerical results demonstrate that an important concentration of no-condensable gas reduces the heat transfer coefficient and film thickness considerably. The local heat flux and film thickness increase as tube surface temperature decreases at any bulk concentration of non-condensable gas. Moreover, inlet velocity increases as film thickness decreases and heat flux increases.