Numerical study of spray cooling with flash evaporation

This work aims to apply Computational Fluid Dynamic (CFD) method to establish a flash evaporation spray cooling (FESC) model to simulate the heating process and find the optimum cooling performance. The heat transfer process during FESC is studied through numerical simulation using commercial code ANSYS FLUENT. The species transport model and the discrete phase model are applied to simulate the multiphase flow and heat transfer process. The turbulence effect is included. The effects of flow rate, nozzle pressure, nozzle angle, and the nozzle orifice size on spray cooling are investigated through analyzing the final surface temperature distributions. This work revealed the mechanism of the heat transfer process in FESC by means of particle tracks and velocity magnitude distribution. The simulated results for the effect of flow rate were compared with other researchers' previous published experimental results. The comparison shows same trend, which verified the model and the simulation result. The optimum cooling performance is found by analyzing various working conditions. The results show that high flow rate, high nozzle pressure, small nozzle angle and small nozzle orifice can improve the FESC characteristics. The detailed mechanisms of these effects under various working conditions are also discussed. Under giving working conditions, the optimum cooling performance is obtained for the condition where mass flow rate of working fluid is 2L/min, the nozzle pressure is 100MPa, the nozzle angle is 15 degrees and the orifice size of the nozzle is 1mm.