Effects of surface roughness and surfactant on film condensation heat transfer of steam

The design of a two phase heat exchanger requires a fundamental knowledge of the parameters affecting film condensation. The interaction of roughened surfaces and change of surface energy by the addition of a surfactant to the system for quiescent steam was examined in this study. Three types of roughened surfaces were generated by roughening a polished surface with sandpaper, electroplating to obtain a thin porous coating of nodules onto the condenser surface, and soldering of porous aluminum foam to the condenser face. The addition of a nonionic surfactant, alcohol alkoxylate, to the system was evaluated for the roughened surfaces. For a Reynolds number less than 50, the roughened surfaces examined all degraded the condensation heat transfer. The addition of a surfactant to the system enhanced condensation heat transfer on polished surfaces almost two fold.