Applicability of a Mechanistic Model for the Prediction of Boiling Heat Transfer for Refrigerants

Among the different mechanisms of heat transfer during nucleate pool boiling, evaporation from the micro layer, evaporation from the macro layer, and transient heat transfer from the fluid mass above the macro layer play very crucial roles. Based on these three mechanisms, a model made earlier by the authors can predict the pool boiling heat transfer of water from flat and tubular surfaces quite accurately. To the best of our knowledge no model has so far been constructed for refrigerants considering evaporation from micro and macro layers. This leaves an opportunity for extending the generic micro–macro layer-based boiling heat transfer model for refrigerants. In the present work the authors' earlier model has been used to predict boiling heat transfer for a number of refrigerants. Experimental data for both flat and tubular surfaces have been considered for the validation of the model. Good agreements have been observed in most of the cases. Although the model is developed for nucleate boiling, it has been extended for a higher degree of superheat, and a matching trend can be seen beyond the critical heat flux for various heat input rates. Values of critical heat flux are also well predicted by the present model.