Effects of interfacial structure on film condensation.

摘要

Film condensation in the presence of a noncondensable gas is expected to be strongly affected by the presence of interfacial structure. An experimental program was undertaken to simultaneously measure a set of parameters for the interfacial waves and the condensation heat transfer coefficient. Experiments were performed in a square test section 100 mm by 100 mm and 1.83 m long. The heat transfer surface was formed by the last 610 mm of the bottom wall. Mass ratios of air to steam could be varied from about 1 to 15. Water films could also be injected to simulate thicker films.;An isothermal air-water series was conducted in which air was blown over a flowing film. The experimental techniques for wave characterization were developed during these tests. Film thickness and wave amplitude, frequency, and celerity were measured. Wavelengths were computed using the measured values. There was good agreement with those observed visually.;Two sets of heated tests were conducted. The first set utilized an injected film. Film and wave parameters were measured using the methods developed in the isothermal runs. The data showed an apparent suppression of the waves by the bulk flow of steam to the interface as was anticipated. Heat transfer data were also taken but were marred by problems with heat balance corrections for the injected film. The second set of heated tests did not use an injected film. Wave parameters were not measured, but visual observations were noted. Heat transfer coefficients compared well with the results of the previously developed theoretical model of M. H. Kim.