Acceleration and the Critical Heat Flux in Pool Boiling Heat Transfer

Abstract

Many theories predicting the critical (or burnout) heat flux in saturation pool boiling have been proposed during the past decade. Although most are able to correlate existing experimental data, it is evident that the theoretical models upon which they are based are widely different in concept. Moreover, owing to lack of experimental evidence it is not clear which, if any, are based upon the more correct models. Certain of the theories implicitly contain the acceleration due to gravity raised to a different power; by performing a relatively simple experiment it may be possible to accept or reject certain of the theories. An experiment of this type is described in the present paper. On the basis of the results of this experiment it is possible to reject several of the above theories. The extent to which the acceleration of the boiling system is important as a parameter in determining the critical heat flux was ascertained experimentally. A simple centrifugal apparatus is described which was used for determining the critical heat flux in pool boiling to water at atmospheric pressure and accelerations in the range 1 < ( a/g) < 160. A two-variable non-linear correlation involving a logarithmic transformation was made upon the experimental results after allowing for the possible effect of pressure and potential sub-cooling by extrapolation to zero subcooling. The resulting equation is of the form: