Experimental comparison of film-wise and drop-wise condensations of steam on vertical flat plates with the presence of air

Abstract

This paper presents experimental results comparing film-wise and drop-wise condensations. The condensing plates were developed to promote film-wise or drop-wise condensation respectively. Rates of heat transfer have been measured on a single face of water-cooled flat plates suspended vertically in a cylindrical test section as steam and mixtures of steam and air flowed over it. In the pure steam cases, the drop-wise condensations showed much higher heat transfer rates than film-wise condensations, which showed good agreements with the Nusselt theory of natural convection condensation. However in the steam and air mixture cases, as expected, both modes of condensations fell in similar range of heat transfer rates. Due to the difference in the condensate flows, the drop-wise condensation showed even lower heat transfer rates than film-wise condensation with the presence of air.