Performance of spray cooling with vertical surface orientation: An experimental investigation

Abstract

• Vertical surface spray cooling system is built and investigated. • The surface temperature is controlled below 120°C with high input power of 650 W. • The maximum critical heat flux of 596 W/cm 2 is achieved. • The interplay of convection and evaporation heat transfer is studied. • Nusselt number correlation in the single-phase regime is proposed. Spray cooling is a promising thermal management solution for high heat flux applications. Surface orientation is a key parameter of spray cooling performance while vertical surface orientation has been proved to have excellent heat transfer performance. However, key spray parameters regarding the vertical surface spray cooling system have not been comprehensively studied. In this work, a vertical surface spray cooling system is designed and established. The effects of spray volumetric flux, nozzle-to-surface distance, and coolant inlet temperature on the heat transfer characteristics of spray cooling are experimentally investigated. The system shows a magnificent heat dissipation capability as high as a critical heat flux of 596 W/cm 2 at a low spray volumetric flux (0.83 × 10 -2 m 3 ·s -1 ·m -2 ). Nozzle-to-surface distance, which has no obvious effect on the two-phase regime, is observed to play a significant role in the single-phase regime. Interestingly, the heat transfer coefficient can be enhanced by increasing the coolant inlet temperature while it will not necessarily lower the surface temperature. Furtherly, an experimental dimensionless correlation of Nusselt number for the single-phase regime is proposed, demonstrating a higher contribution of coolant flow properties to the spray cooling system performance with vertical surface orientation. This work reveals the underlying mechanism of how the key spray parameters impact the performance of the spray cooling system with vertical surface orientation and is expected to facilitate high-heat-flux heat dissipation and provide guidance for the research on spray cooling.