A two-phase boundary-layer model for laminar mixed-convection condensationwith a noncondensable gas on inclined plates

A finite-volume-based numerical model for mixed-convection laminar film con densation from a flowing mixture of a vapor and a heavier noncondensable ga s on inclined isothermal flat plates is presented. The full boundary layer equations for the liquid film and the vapor-gas mixtures (including liquid inertia and energy convection terms) are solved implicitly with appropriate liquid-mixture interface conditions. Results were obtained for three mixtu res, covering wide ranges of liquid Prandtl number and free-stream gas conc entration in the forced-convection, mixed-convection and free-convection fl ow regimes. The effects of liquid inertia were found to be significant only for low-Prandtl-number fluids and lower gas concentrations. The effects of liquid energy convection were found to be significant only for high-Prandt l-number fluids and to be most significant for mixed-convection condensatio n.