The Effect of Polyvinylidene Chloride Coating Thickness to Promote Dropwise Condensation of Steam

Abstract

The surfaces of dropwise condensation coated with noble metals are more expensive than those coated with polymers. In this paper we proposed the use of polyvinylidene chloride coatings as the promoter and investigated the effect of the thickness of the coatings to promote dropwise condensation of steam. Four kinds of thicknesses, 0.05μm, 0.10μm, 0.25μm and 0.50μm were examined. The surface was heat-set for 83 hours after each coating. Then each surface was evaluated for its ability to promote and sustain dropwise condensation of steam. The 0.05μm coating showed dropwise condensation as high performance of heat transfer as gold or oleic acid promoter surface. All thicknesses of film showed no signs of deterioration of promotion, for example the coating did not peel or crack even after heat transfer tests of transition of dropwise-filmwise-glacial condensation. The 10μm thickness of film was visually evaluated in its ability to promote and sustain dropwise condensation of steam for a long term. While exposed to steam at atmospheric pressure, good appearence of dropwise condensation was observed over a priod of 8076 hours.