Numerical analysis of heat transfer performance in water spray cooling under low atmospheric pressure

Abstract

Spray cooling has gained significant attention as an efficient thermal management strategy in various industrial and aerospace applications. In this study, we numerically investigate the heat transfer characteristics of low ambient pressure spray cooling systems using a Euler-Lagrangian approach to simulate two-phase boiling over a pressure range of 20–100 kPa. Results show that at a mass flow rate of 0.00468 kg/s, the heat transfer coefficient increases by up to 76.17 % at an ambient pressure of 20 kPa compared to atmospheric condition. Microscopic analyses reveal that flash evaporation at lower pressures promotes strong droplet-wall interactions and enhanced boiling heat transfer. Moreover, at 40 kPa, the temperature distribution reversal is evident. Consequently, we further examined mass flow rate effects at this representative low pressure and found a critical threshold beyond which maximum heat transfer performance is achieved. It is noteworthy that the time to reach thermal equilibrium becomes shorter under lower ambient pressures, indicating a faster dynamic response compared to atmospheric condition. These findings expand the understanding of spray cooling in low ambient pressure and offer practical guidelines for optimizing both system design and operation.