Study on drop wise condensation by using functionalized heat transfer surface

Koizumi, Yasuo; Yoshizawa, Shota*

The enhancement of drop wise condensation heat transfer by functionalizing a heat transfer surface was examined for 0.1 MPa steam. A gold-plated surface was used to produce the drop wise condensation. Rectangular-grooved heat transfer surfaces were adopted to functionalize the heat transfer surface. The size of the grooves were 2 mm 2 mm 2 mm, 3 mm 3 mm 3 mm and 2 mm 3 mm 2 mm (depth top width bottom width), respectively. The heat flux of the grooved surface was larger than that of the plain gold-plated surface. When the groove size was 2 mm 2 mm 2 mm and the top parts and the walls of grooves were plated with gold, the heat transfer rate augmentation was highest; the augmentation rate was 1.53. Since to increase the width of the top part of the grooves tended to bring the quality of the surface structure close to the plain surface, it was not right direction. It was also implied that to make summits and troughs on the surface to collect condensate tended to expose the summit part to steam more, which might result in the heat transfer augmentation.