Experimental study on heat transfer and power consumption of low-pressure spray cooling

Abstract

In this study, an experimental system was built to comprehensively investigate the heat transfer characteristics and power consumption of low-pressure spray cooling. The heat transfer performance and effective power consumption was calculated according to the spray pressure, and the flow rate of the heating surface were evaluated under varied spray pressures (0.1–3 bar), spray heights (5–30 mm), and heat flux (20–70 W/cm2). At low spray pressure, the heat transfer coefficient is small but could still reach a value of 1.8 W/cm2K, and the power consumption is considerably lesser. The heat transfer coefficient is maximized at an optimal spray height. In addition, the optimal height is influenced by the spray pressure. Interestingly, when the pressure was increased to 0.5 bar, the optimal spray height, H = 15 mm, was unchanged. Based on a comprehensive consideration of the heat transfer performance and effective power consumption, a performance evaluation criterion was proposed to quantify the overall performance of the spray. Remarkably, the performance evaluation criterion value of the spray was the highest at low pressures. In addition, from the perspective of comprehensive performance, it was found that the variation in performance evaluation criterion value corresponded to that of the heat transfer coefficient and that an optimal height exists at which the performance evaluation criterion value can be maximized. This research can provide significant guidance for the efficient operation of low-pressure spray cooling systems.