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Next: Observations Up: POST-CHF HEAT TRANSFER Previous: Transition Boiling
Consider the case when the mass velocity decreases to very low value. As G decreases the flow situation becomes more like pool boiling where the post-CHF regime becomes film boiling. Because the liquid is displaced from the heating surface by a vapor film and the uncertainties associated with bubble nucleation are removed, film boiling is very amenable to analytical solution. This is similar to condensation where stratified flow occur with a liquid film. In general, the problem is treated as an analogue of film-wise condensation and solutions are available for horizontal and vertical flat surfaces, and also inside tubes under both laminar and turbulent conditions with and without interfacial shear. It is not, however, proposed to review all these solutions here and the reader is referred to the comprehensive reviews of Clements and Colver (1970), of Hsu (1972) and of Bressler (1972).