Pseudo-potential MRT - thermal LB simulation of flow boiling in vertical tubes

Abstract

The flow boiling in vertical tubes is simulated by the MRT pseudo-potential - thermal LB model to study the effect of contact angle. No empirical correlations are given in this simulation. To validate the model, the relationship between the acceleration of gravity and the departure velocity of bubble in the departure period is compared with the empirical formula. The effect of dynamic contact angle on boiling is investigated. The simulation results of the dynamic contact angle and the static contact angle show that the dynamic contact angle has great influence on the bubble behavior. The key features of dynamic contact angle, i.e. the advancing contact angle, receding contact angle and contact angle hysteresis, are investigated. The mechanisms of differences of entire bubble period and bubble departure diameter under various contact angles are discussed. The heat transfer coefficient, the critical heat flux and the flow pattern of different surfaces are investigated. The results suggest that the critical heat flux of hydrophilic surface are higher than that of hydrophobic surface.