Laminar film condensation in a vertical tube in the presence of noncondensable gas

A two-dimensional, steady state model of convective film-wise condensation of a vapor and noncondensable gas mixture flowing downward inside a vertical tube is developed. The mass transfer at the film and gas interface is treated as diffusion controlled process. The noncondensable effect on the condensation is taken into account through boundary layer analysis of species concentration and energy balance. Numerical predictions were obtained for the condensation heat transfer coefficient of turbulent vapor flow associated with laminar condensate. The predictions were compared with the experimental data in the literature to assess the model. Noncondensable mass fraction and vapor–noncondensable mixture temperature were presented in the form of radial and axial profiles.