Free-Convection Condensation of Steam on a Vertical Surface in the Presence of a Small Amount of Noncondensing Gas.

Abstract

Similarity solutions for free-convection condensation of an air-steam mixture, where the bulk air mass concentrations W1V∞ are 0.1, 0.01 and 0.001 and the bulk temperatures TV∞ are 100, 65.56°C and 26.67°C, are presented. From the solutions, a new correlation equation for the gradient of W1V at the vapor-liquid interface is obtained. It is confirmed that this equation agrees well with the similarity solutions not only for an air-steam mixture with large W1V∞ values but also for mixtures of ethanol-water and CFC114-CFC11. The algebraic solution using the equation compares well with existing experimental results, even for a helium-steam mixture when the absolute value of the buoyancy term is taken. It is also discussed that the discrepancy between the theoretical solution and the experimental results by Slegers and Seban may be caused by the choice of the representative value of the bulk mass concentration rather than by the effect of forced convection.