Experimental investigation on heat transfer of spray cooling with isobutane (R600a)

• The mass flow rate has a positive influence on heat transfer coefficient.
• h is up to 35,000 W/(m2 K) when q is 132 W/cm2, and Tsur can be maintained below 52 °C.
• With the increase of the chamber pressure, h is enhanced from 19,000 W/(m2 K) to 23,000 W/(m2 K).
• The increase of the nozzle inlet pressure will increase the mass flow rate and enhance the atomization.

In order to enhance the heat transfer performance of spray cooling system, an integrated system is developed. The system is based on the refrigeration cycle, and uses isobutane (R600a) as the coolant. The heat transfer performance, such as the heat surface temperature, the heat transfer coefficient and the surface temperature distribution, are experimentally investigated in this paper. When the coolant mass flow rate is nearly 6.9 kg/h, the surface temperature can be kept at 57.3 °C with the heat flux of 145 W/cm2. The heat transfer coefficient can be achieved up to 35,000 W/(m2 °C) when the nozzle inlet pressure and the chamber pressure are 4.9 bar and 2.3 bar, respectively. The surface temperature uniformity is mainly influenced by the mass flow rate, the heat flux and the nozzle inlet pressure together, and the standard deviation of the surface temperature is less than 4.0 °C in this study. All the results indicate that this system is promising in the application for high heat flux removal.