Effect of Superheat and Cavity Size on Frequency of Bubble Departure in Boiling

Abstract

A theoretical model has been developed to predict the effect of cavity size (both radius and depth), and superheat on frequency of bubble departure by considering the effect on waiting time (time between the last bubble departure and appearance of the next one on the surface) and bubble growth time. An increase in cavity size or decrease in surface superheat results in longer waiting time and bubble growth time, thus causing a lower frequency. The model explains qualitatively the observed effect of superheat and cavity size on bubble departure frequency during pool boiling experiments with water on artificial cavities drilled by laser.