The plasma polymerization method and dynamic ion-beam mixed implantation method were employed to coat ultra-thin polymer films on copper plates. Experiments indicated that steady dropwise condensation of steam at atmospheric pressure occurred. The condensation heat transfer coefficients increased by approximately 3 and 5－7 times for the polytrimethylvinylsilane film and polytetrafluoroethylene film respectively, compared with the value for film condensation under the same experimental conditions. The temperatures on the condensing surface and inside the test block were found to be rapidly and randomly fluctuated. The properties of the coated films and advantages of the methods used in this investigation were discussed briefly.
In order to study the influence of solid liquid interfacial energy on the filmwise condensation heat transfer performance, a correlation relating heat transfer coefficient with contact angle was derived with respect to liquid film flow and heat transfer at vapor liquid interface. The calculated results for steam filmwise condensation indicated that heat transfer coefficient increased with increasing contact angle when the contact angle was within a certain range. When contact angle was very small (approaching 0°), the predicted heat transfer coefficient was consistent with the result of classic Nusselt theory.
