On the Stability of Vapor Film in Pool Film Boiling

Abstract

The stability of vapor film in pool film boiling on a horizontal surface is considered by taking account of the effect of change in the local heat transfer rate due to the perturbation of vapor film thickness. It is shown that a vapor film below a certain critical thickness becomes stable over all disturbances with any wavelength. Assuming that the average film thickness during the actual film boiling is proportional to the foregoing critical film thickness, the heat transfer coefficient can be derived. The predicted heat transfer coefficient agrees well with the recent film boiling data obtained in a range of unprecedentedly low surface superheat by Shoji using a very large surface.