A transient micro-convection model of nucleate pool boiling

This work advances the fundamental understanding of nucleate pool boiling on plain surfaces. A model is developed for prediction of the nucleate boiling coefficient as a function of the bubble dynamics characteristics (nucleation site density, bubble departure diameter and bubble frequency). This work extends that of Mikic and Rohsenow, who developed a model based on transient conduction to the superheated liquid layer. The present model includes the effects of transient convection to the liquid, as a result of convection in the wake of the departing bubbles. An asymptotic correlation is used to patch the transient conduction and the steady-state convection asymptotes to cover the full bubble cycle. The predicted heat transfer coefficient is compared using data for R-11 and R-123, and good agreement is found. The model shows that the contribution of transient conduction is small compared to transient micro-convection. It is believed that this is the first successful demonstration of a mechanistically based model for nucleate boiling on plain surfaces. (C) 1997 Elsevier Science Ltd.