Numerical solution of the complete two-phase model for laminar film condensation with a noncondensable gas.

摘要

Laminar film condensation, of a vapor-noncondensable gas mixture on a flat isothermal surface, with quiescent or moving mixtures, is analyzed. Surface orientation varied from vertical to horizontal and variable properties are used. Using a finite control volume approach, the full boundary layer equations for conservation of mass, momentum, energy and species (mixture only) for both the liquid and vapor-gas mixture phases are solved in primitive variable form. The focus of this thesis is on developing the velocity and temperature fields in both phases and gas concentration profile in the vapor-gas mixture phase, as well as the film thickness, the heat transfer coefficients and the condensation rate. These results are then used to assess the effects of neglecting the inertia terms in the liquid momentum equation and the energy convection terms from the liquid energy equation. Dimensionless parameters are also developed allowing the results to be presented in a generalized format.;Results are obtained for three different vapor-gas mixtures to examine a wide range of Prandtl number, Pr;The inertia terms in the liquid momentum equation were found to have negligible effect on the hydrodynamic and thermal characteristics of the flow for both the steam-air and glycerin-bromine mixtures. The inertia terms had the greatest effect on pure sodium, with the deviation decreasing with increasing argon gas concentrations, such that when the free stream gas concentration is increased to 10;Furthermore, the energy convection terms in the liquid energy equation were found to have negligible effect on the hydrodynamic and thermal characteristics of the flow for both the steam-air and sodium-argon mixtures. The effect of neglecting the energy convection terms for the glycerine-bromine is to underpredict the heat transfer coefficient, with the error reaching a maximum between the horizontal forced convection limit and the free convection limit. (Abstract shortened by UMI.)