Design, fabrication, and testing of high capacity high-temperature Monel/water heat pipes

A development program was completed to demonstrate key technologies required for the JIMO Heat Pipe Radiator. Part of this work included the design, assembly, and performance testing of two favorable wick designs in full length water heat pipes. A parametric study identified CP-2 titanium and Monel K-500 alloys as favorable envelope materials. The design effort also identified two promising wick designs Based on porous-walled axially grooves. Several heat pipes of each design were assembled and tested. The heat pipes were tested at temperatures up to 300 degrees C under several tilt conditions. A sintered groove evaporator design operated at up to 1500 W against gravity at temperatures between 280 degrees C and 300 degrees C, and an inverted meniscus evaporator designs operated at up to 1200 W at similar temperature and tilt conditions. Based on the test results, the sintered groove wick design is recommended for further development. One of the heat pipes was also subjected to a startup from an initially frozen condition. A neon inert gas charge of 16 cc was added to the devices to promote successful frozen startup. A favorable response observed from this test provides confidence that the design will survive and operate under a frozen startup condition.