Mesoscale simulations of boiling curves and boiling hysteresis under constant wall temperature and constant heat flux conditions

Mesoscale simulations for pool boiling curves and boiling hysteresis on hydrophilic/hydrophobic surfaces, under constant wall temperature/constant wall heat flux conditions, are presented in this paper. It is found that simulated boiling curves in dimensionless form under these two different heating modes are identical in nucleate boiling and film boiling regimes, and they differ only in the transition boiling regime. Saturated temperatures have relatively small effects on boiling curves up to the fully-developed nucleate boiling regime, but have pronounced effects on critical heat flux and on film boiling. Boiling hysteresis between increasing heating and decreasing heating are also simulated numerically. It is confirmed numerically that boiling hysteresis exists in transition boiling regime for both hydrophilic and hydrophobic surfaces under controlled wall heat flux conditions. Under controlled wall temperature conditions, however, boiling hysteresis exists only on a hydrophobic surface during decreasing heat flux but no boiling hysteresis exists on a hydrophilic surface. Rohsenow's classical correlation equation for nucleate boiling heat transfer matches well with simulated nucleate boiling heat transfer results for smooth horizontal superheated surfaces. Simulated critical heat fluxes are in qualitative agreement with those predicted by Zuber's hydrodynamic model and by Kandlikar's analytical model.