Development of a Flexible Loop Heat Pipe Cold Plate

The current trend in military avionics design is to physically move electronics closer to the components they control. This saves on weight, increases component maintainability, reduces aircraft manufacturing costs, and reduces the amount of electromagnetic shielding. A disadvantage to this trend is the difficulty in achieving thermal control of these remotely located electronics.

Accordingly, this thermal control issue is being addressed through the development of a flexible loop heat pipe cold plate (FLHPCP). The FLHPCP is different than previous hardware of its kind by the fact that it operates in any orientation. The prototype FLHPCP that was fabricated and tested was 29 inches long and weighed 1.7 pounds. At full adverse orientation (evaporator vertically above condenser), the prototype met the 45 watt heat load requirement at an average evaporator cold plate-to-condenser cold plate temperature drop of 20°C. Reduction of this temperature drop is planned in future development. In addition, the prototype was tested in the adverse orientation and shown capable of transporting at least three times this heat load.

The FLHPCP is flexible to allow relative motion between the package to be cooled and the heat sink. It also allows cooling to be provided to surfaces in awkward locations relative to the heat sink. Connections to the heat sink can be anything from convective air cooled fins to solid plates bolted on the aircraft's structure.