An 820-Watt clamshell module was fabricated and tested in order to assess the feasibility of cooling future high heat flux avionic hardware via subcooled phase change. One half of the module was constructed from aluminum 7075-T6 and populated with 16 heat sources simulating microelectronic chips. The other half was substituted with a transparent plastic cover to facilitate optical access to the boiling taking place in the module cavity. A dielectric coolant, Fluorinert FC-72, was supplied to, and rejected from the module via sleeveless quick connection couplers. Tests were performed with an inlet coolant pressure of 1.52 bar (22 psia) and inlet temperatures ranging from 27 to 47°C. These tests yielded power dissipation exceeding 410 W per half module for coolant flow rates and pressure drops as small as 0.023 kg/s (0.221 gpm) and 0.149 bar (2.16 psia), respectively, and the device and rib guide temperatures were maintained below 80 and 60°C, respectively. The pressure drop remained constant with increasing module power proving, as was confirmed visually, it is possible to condensate all the vapor within the module cavity, allowing only liquid to exit the module. Thus, coolant conditioning external to the module can be greatly simplified by employing a simple single-phase liquid flow loop.

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