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A passive cooling approach for aircraft electromechanical actuators (EMAs) supports technology development under the Air Force More Electric Airplane (MEA) program. A two-phase coolant is used in a thermosyphon type cooler that transfers heat from the hot electric motor to a cool structural surface. Energy storage is also incorporated, in the form of phase change material, to provide a load leveling function between peak loads and low loads.

Potential applications for high-power electronics in the aerospace industry are increasing at a rapid rate with the development of new switch technologies for high switching power. Inherent in these trends are rapidly increasing heat fluxes and severe difficulty in minimizing silicon operating temperatures to satisfy reliability requirements. Various new technologies are presented that have been developed to meet the difficult cooling requirements of high-density power electronics equipment for the aerospace industry. These enhanced cooling techniques have also been optimized to meet the maintainability requirements of future applications.

A unique heat exchanger has been developed with potential applications for cooling high power density electronics and perhaps high energy laser mirrors. The device was designed to absorb heat fluxes of approximately 50 w/cm2 (158,000 Btu/hr.ft2) with a low thermal resistance, a high surface temperature uniformity and very low hydraulic pumping power. A stack of thin copper orifice plates and spacers was bonded together and arranged to provide liquid jet impingement heat transfer on successive plates. This configuration resulted in effective heat transfer coefficients, based on the prime surface, of about 85,000 w/m2 °C (15,000 Btu/hr.ft2 °F) and 1.8 watts (.002 HP) hydraulic power with liquid Freon 11 as coolant.