Numerical investigation on heat transfer of water spray cooling from single-phase to nucleate boiling region

Abstract

In the present study, spray cooling heat transfer characteristics were numerically investigated under the heat flux ranging from 50 to 170 W/cm2. Effect of nozzle height and spray pressure was also studied in order to reveal the microscopic mechanisms of the heat transfer enhancement from single-phase to nucleate boiling regions. A two-phase flow heat transfer model was adopted based on the Euler-Lagrangian approach. The dependence of thermo-physical properties of fluid on the temperature was also taken into account. The comparison between simulated wall temperature and experimental data demonstrates a satisfactory agreement. The results show that the heat transfer coefficient increases monotonously with the heat flux. In the nucleate boiling region, the wall film is thinner with a smaller velocity compared with those in the single-phase region. Spray cooling heat transfer is enhanced evidently as the nozzle height decreases and the spray pressure increases. The most important feature which separates the present study from the literature is that the numerical simulation in this paper presents some detailed microscopic characteristics, e.g. the wall film thickness and velocity, which play an important role in spray cooling heat transfer.