Optimization of an open-loop high-power flash cooling system with microchannel heat sink and multi-nozzle spray under low environment pressure

Thermal management of high-power airborne electronic devices faces challenges due to insufficient cooling performance of traditional airborne technologies using air and fuel, as well as the limited amount of cooling medium that can be carried on board. In this study, we utilize water due to its highest latent heat of vaporization as the consumable working fluid and develop an open-loop high-power flash cooling system. A novel heat exchange module combining multi-nozzle spray (MSP) and microchannel heat sink (MHS) is proposed. With the objectives of optimizing heat transfer characteristics and minimizing system weight, the effects of system operating parameters and heat exchange module design are investigated experimentally. The results show that lowering the chamber pressure and increasing the hot side inlet temperature can both enhanced heat transfer. Optimization on the MSP indicates that there is an optimal nozzle aperture that maximizes the vaporization ratio and coefficient of performance (COP). Optimization of the MSH shows that using a combination of two types of turbulence structures achieves the highest heat transfer rate, with a power efficiency coefficient (PEC) of 2.67. After final optimization, the MSP-MHS heat exchange module achieves a heat transfer rate of 4604 W and a maximum vaporization ratio of 44.6 %.