The enhancement of dropwise condensation by wettability modification of solid surface

The method of solution dipping was used to prepare the stearic acid film for the purpose of obtaining a good surface to achieve dropwise condensation. The wettability, uniformity and stability of the films were detected by a dynamic contact angle analyzer. Experimental results show that a heterogeneous film is obtained and the uniformity and hydrophobic property can be improved by appropriate heat treatment. A long treating time is required at a lower annealing temperature, but it can be shortened by elevating the annealing temperature. However, for the higher annealing temperature (250 degrees C), the deposited stearic acid may re-evaporate so that the contact angle will become smaller when the annealing time is longer. In general, the properties of the films prepared by the present process were inferior to those obtained by the vacuum deposition in our previous work. (C) 1998 Elsevier Science Ltd