Heat and Mass Transfer of Laminar Free Convection Film Condensation of Pure Vapor

Abstract

With heat and mass transfer analysis, the theoretical equations for Nusselt number and mass flow rate are provided for the laminar free convection film condensation of vapor where only the wall temperature gradient and condensate mass flow rates are unknown variables, respectively. With increase of the wall subcooled grade, the wall temperature gradient will decrease, especially for lower wall subcooled grade. While, with increase of the vapor bulk superheated grade, the wall temperature gradient will increase. However, the effect of the wall subcooled grade on the wall temperature gradient is more obvious than that of the vapor bulk superheated grade. With increase of the wall subcooled grade, the condensate film thickness will increase, especially for lower wall subcooled grade, while with increase of the superheated grade, the condensate film thickness will decrease. However, the effect of the wall subcooled grade on the condensate film thickness is more obvious than that of the vapor bulk superheated grade. With increase of the wall subcooled grade, the velocity components will increase, especially for the small value of the wall subcooled grade. While with increase of the vapor bulk superheated grade, the velocity components will decrease. As per the results, with increase of the wall subcooled grade, the condensate mass flow rate parameter will increase, especially due to the function of condensate film thickness. While with increase of the vapor bulk superheated grade, the mass flow rate parameter will decrease. However, the effect of the wall subcooled grade on the condensate mass flow rate parameter is more obvious than that of the vapor bulk superheated grade. On the basis of the rigorous numerical solutions, the wall temperature gradient and then mass flow rate parameter are formulated, and then the formulated equations for reliable predictions of heat and mass transfer are created for heat and mass transfer application of the laminar free convection film condensation of water vapor.