Evaluation of organic coatings for the promotion of dropwise condensation of steam

Abstract Several new polymer coatings, as well as gold and silver, were evaluated for their ability to promote and sustain dropwise condensation of steam. Long-term behavior on 25-mm-square specimens was qualitatively observed in an endurance apparatus and heat transfer coefficients on single horizontal tubes were determined in a separate heat transfer apparatus. The organic coatings were successful in promoting good quality dropwise condensation for prolonged periods of times (> 12,000 h). Dropwise heat transfer coefficients as large as six times the film condensation value were obtained with these coatings and results were not dependent upon the thermal conductivity of the wall.