Multi-nozzle array spray cooling for large area high power devices in a closed loop system.

A prototype of a closed loop system was built to study multi-nozzle array spray cooling on high-power, large-area electronic devices. Fifty-four nozzles with an in-lined array of 9 × 6 were applied to spray cool a simulated 6U electronic card using R134a. Simple drainage concepts were introduced to assist the drainage of both liquid and vapour on the heated surface. The results indicated a promising prospect of using a multi-nozzle array on large-area power electronics cooling. 16 kW heat was removed from the 6U card area by maintaining the mean surface temperature below 26.5 ° C . Heat transfer coefficient up to 2.8 × 10 4 W / m 2 K was obtained, and liquid usage fraction as high as 0.88 was achieved before CHF occurred. It was found that increasing nozzle pressure drop or flow rate enhanced heat transfer and gave better surface temperature uniformity. Chamber pressure significantly influenced mean surface temperature, but had no observable effects on surface temperature uniformity. The control of chamber pressure can maintain a constant temperature on the heated surface when heat load varied largely. The results also showed that the spray-to-spray interactions had inconspicuous effects on local surface temperatures but rather the distance from a location relative to the drainage outlets. [ABSTRACT FROM AUTHOR]