Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

TL;DR

This paper introduces a new lattice Boltzmann model for simulating boiling heat transfer, successfully reproducing the boiling curve and analyzing the effects of wettability on boiling behavior.

Contribution

The study presents the first numerical reproduction of the boiling curve using a hybrid thermal lattice Boltzmann model that avoids previous spurious effects.

Findings

The model captures the three boiling stages and heat flux fluctuations.

Wettability influences boiling onset and critical heat flux.

Increased contact angle promotes boiling but reduces critical heat flux.

Abstract

A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach [Q. Li, K. H. Luo, and X. J. Li, Phys. Rev. E 87, 053301 (2013)]. The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid-vapor phase change. Using the model, the liquid-vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic features and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Furthermore, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies.