Numerical simulation of single bubble growth and heat transfer considering multi-parameter influence during nucleate pool boiling of water

Abstract

Nucleate boiling is an essential heat exchange method in industry. Due to the complicated mechanisms of the boiling process, prediction of its heat transfer performance has always been challenging. Studying the growth and heat transfer characteristics of a single bubble is of great significance for understanding the internal mechanisms of nucleate boiling. In this paper, single bubble growth in saturated pool boiling was numerically studied. The microlayer evaporation at the bubble base was calculated and added to the simulation via UDFs. The effects of contact angle, wall superheat, and microlayer initial thickness distribution were investigated. The results show that a thinner microlayer has a greater evaporation rate, resulting in an increased bubble growth rate and departure diameter. The bubble growth rate, departure time, and departure diameter increase with the increase in the contact angle and wall superheat. As the wall superheat increases, there is a competition between microlayer evaporation and phase interface evaporation, which ultimately leads to an extremum of the total contribution of microlayer evaporation to bubble growth. The heat transferred by microlayer evaporation accounts for at least 67.3% and up to 83.6% of the bubble's latent heat at departure, indicating that microlayer evaporation has a significant impact on bubble growth.