Thermal Testing of Arrays of PHP Finned Plates for Enhanced Air-Cooling of Electronics

Several recently patented (joint Chinese patent of JJ Cooling Innovation and Novark Industries [1]) air-cooled flat plate pulsating heat pipe (PHP) designs were tested individually and the results were presented at ITHERM 2022 [2]. A continuation of this work is presented here for the same flat plate pulsating heat pipes now mounted in an array on a base board to mimic the cooling of board-mounted power electronics and high-power telecommunication base stations. Tests were performed with arrays of: (1) plain thin solid aluminum plates, (2) PHP fin plates without louvers and (3) PHP fin plates with louvers in completely passive mode (natural convection of air and self-excitation of the PHP) and in fan-driven operation. The low global warming potential (GWP) fluid R1233zd(E) was used as the working fluid in the PHPs. Tests results demonstrated that in natural convection conditions, the maximum dissipated power ensuring a case temperature lower than 80 °C was 25% higher with both arrays with PHP cooling plates compared to the aluminum fin array and that the case temperature was up to 5.6 °C lower for the same heat dissipation. In forced convection conditions, the case temperature did not exceed 80 °C for a power dissipation 40% higher with the two arrays with PHP cooling plates compared to the aluminum plain fin array and a reduction of 9.5 °C for the case temperature was observed. These results in forced convection were obtained with a low power consumption fan which yielded cooling load to fan power consumption performance ratios up to 139.