An experimental investigation of film condensation of flowing mixtures of steam and air on a vertical flat plate

The effects of the flowing mixture of steam and air to the condensation heat transfer were investigated experimentally at atmospheric pressure varying the air concentration. Rates of heat transfer have been measured on a single face of a water-cooled flat plate suspended vertically in a cylindrical test section as steam and mixtures of steam and air flowed over it. The measured heat transfer rates for the pure steam case showed good agreements with the Nusselt theory of natural convection condensation. However, in the steam and air mixture cases, the small mixture flows enhanced the heat transfer rates. The measured heat transfer rates were within the envelops of natural and forced convection condensations with more shift to the force convection condensation. At large sub-cooling temperatures, the ratios of heat flux with and without air increased by the stronger sweeping effect of the mixture flows to the thicker air-rich layers. It is concluded that the small steam flow over the cooling plate shows negligible effect to the condensation heat transfer but the mixture flow enhances the heat transfer substantially. (C) 2004 Elsevier Science Ltd.