Comparative Study of Double-Sided Spray Cooling System Under Atmospheric and Sub-Atmospheric Ambient Pressures

Spray cooling is a highly efficient cooling technique that is widely used on the ground, but is more challenging with regards to the thermal management of airborne microelectronics due to sub-atmospheric ambient pressure. In this study, we experimentally analyzed a double-sided spray cooling system designed to cool the two sides of a copper block with different heat fluxes and spray coolant flow rates at sub-atmospheric and atmospheric ambient pressures. The results show that under sub-atmospheric ambient pressure, the cooling rate is higher, cooling surface temperature at steady state is lower, and the heat transfer coefficient is higher. The cooling efficiency and overall performance, considering both heat transfer coefficient and effective power consumption, are significantly improved under sub-atmospheric ambient pressure. Additionally, the cooling efficiency under sub-atmospheric ambient pressure is more sensitive to lower flow rates. The overall performance is 40% greater compared to that under atmospheric ambient pressure. This study can facilitate the development of double-sided spray cooling system for airborne microelectronics.