Lattice Boltzmann Study on Influence of Gravitational Acceleration on Pool Nucleate Boiling Heat Transfer

Under both normal gravity and microgravity conditions, pool boiling is an efficient mode of heat transfer which has been widely applied in practice. Studying the influence of gravitational acceleration on boiling heat transfer is not only of academic significance, but also helpful for the design of space equipment related to boiling. With the development of computer technology, numerical method has been a new reliable way to investigate the boiling heat transfer under different gravities. Pseudopotential lattice Boltzmann (i.e., LB) model is one of the most popular multiphase LB models, in which the phase interface could be formed, disappeared and migrated naturally. In this paper, the Multi-Relaxation-Time (i.e., MRT) pseudopotential LB model coupled with phase-change model was applied to simulate the pool boiling heat transfer under different gravitational accelerations and wall superheats. Pool boiling curves under different gravities were obtained. It's found that: 1) the pool boiling heat transfer coefficient at a given wall superheat decreases with a decrease in gravity; 2) the wall superheat, as well as heat flux, at the CHF (i.e., critical heat flux) point and ONB (i.e., onset of the nucleate boiling) decrease gradually with a decrease in gravity. In addition, based on the numerical results, a new gravity scaling model was proposed to predict the influence of gravitational acceleration on the nucleate boiling heat transfer under different wall superheats. Finally, the new gravity scaling model was proved to be capable of predicting the heat flux during the nucleate boiling under different wall superheats and gravities