Mesoscale simulations of saturated pool boiling heat transfer under microgravity conditions

Abstract

Microgravity effects on pool boiling heat transfer from a horizontal hydrophilic surface under constant wall temperature are simulated numerically based on an improved liquid-vapor phase-change lattice Boltzmann method with the imposition of a conjugate thermal boundary condition at solid/liquid interface. Effects of microgravity on bubble departure diameter and bubble departure frequency are investigated. Both the bubble departure diameter and the duration of one bubble cycle are found to be increasing with decreasing gravity levels. Boiling curves under normal gravity and microgravity are numerically obtained and compared. It is shown that gravity has significant effects on pool boiling curves from nucleate boiling to critical heat flux, and from transition boiling to film boiling heat transfer. Moreover, the critical heat flux is lower and it occurs at a lower wall superheat under microgravity conditions than under normal gravity. Effects of heater size in pool boiling under both of microgravity and normal gravity conditions are investigated as well.