Optimizing spray cooling systems: A comprehensive study on influential parameters and their effects on heat transfer under varied heat flux conditions

Abstract

This research explores the heat transfer characteristics of spray cooling under heat flux conditions ranging from 10 to 200 W/cm2 through numerical simulations. We examined the effects of spray height, spray pressure, surface tension, contact angle, system pressure, and gravity on spray cooling efficiency, to optimize spray cooling systems. Furthermore, we validated the simulation results through experiments and found a good agreement between the two. Key findings include a consistent increase in the heat transfer coefficient with rising heat flux. Under specific heat flux density, increased spray pressure leads to a gradual decline in wall temperature and improved wall temperature uniformity, but the reduction rate slows as pressure continues to increase. Lower spray heights can improve cooling efficiency, but may reduce temperature uniformity. Additionally, heat transfer performance in the two-phase zone improves with higher surfactant (Tween 20) concentration, with a 75ppm solution reducing cooling wall temperatures by 7.4 K compared to pure water. Spray processes at 10 kPa and 50 kPa result in lower wall temperatures before entering the two-phase zone compared to atmospheric pressure, improving cooling efficiency and temperature uniformity. Finally, differences in spray cooling effects under varying gravities manifest primarily during the two-phase heat exchange stage, with the temperature difference widening with increasing heat flux density. These insights offer valuable guidance for spray cooling applications in electronic thermal management.