Convective Condensation of Methanol Vapor in Presence of a Non-Condensable Gas with Turbulent Flow in Vertical Tube

Abstract

The problem of turbulent film condensation of methanol vapor in the presence of concentration non-condensable gas such as humid air flowing in a vertical tube under turbulent forced convection conditions is formulated theoretically. The vapor condensing at dew point temperature releases both sensible and latent heats and diffuses on to the surface of the. Thus it is treated as combined heat and mass transfer problem governed by mass, momentum and energy balance equations for the vapor-gas mixture and diffusion equation for the vapor species. The flow of the falling condensate film is governed by the momentum and energy balance equations. 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.