Parametric investigation on the close-loop R410A flash spray system for high power electronics cooling under low temperature

For high power density electronics, flash spray cooling is one of the most effective ways of dissipating heat at safe working temperature. Spray parameters exert significant influences on the heat transfer capacity. This paper conducted an experimental investigation to explore the influences of spray chamber pressure, mass flow rate and subcooling degree on the cooling capacity on a flat heated surface in a spray cooling cycle using R410A as the working fluid. The results indicated that the initial increases in spray chamber pressure, mass flow rate and subcooling degree all improved the heat transfer performance. The best cooling performance was achieved once these parameters reached their optimal values; those were 0.57 MPa, 4.9 g/s and 5 °C respectively. The subsequent increase of them deteriorated spray cooling heat transfer, decreasing critical heat flux and heat transfer coefficient while increasing surface temperature. The main reasons responsible for the heat transfer were related to the atomization performance of flash spray affected by the spray parameters. The critical heat flux and maximum heat transfer coefficient yielded on a simple flat copper surface achieved 300 W/cm2 and 550 kW/(K m2) while surface temperature was maintained below 30 °C under the optimal spray parameters.