Pulsating Heat Pipe Experiments for Microgravity Sounding Rocket Tests

Two flat plate diffusion-bonded pulsating heat pipes (PHPs) for the thermal management and heat dissipation of concentrated heat flux in electronics applications, such as aboard satellites and spacecraft, were specially developed for future tests aboard a sounding rocket in microgravity conditions. Both devices contain 26 channels with round cross sections, one with ultrasharp lateral grooves in the evaporator. Two heat sinks were tested: a water-cooling bath for the thermal characterization of the PHPs, and a copper box with a phase change material (dodecahydrate bibasic sodium phosphate) to be qualified as the heat storage for future microgravity tests. Water was used as the working fluid. The best filling ratio (relative to the total internal volume of the PHPs) was experimentally determined to be 50%, for which the devices presented the earliest startup and the lowest thermal resistance, around 0.033 & DEG;C/W for the grooved PHP. This research proposes an efficient and alternative cooling method, the phase change material storage, to be used as a heat sink in future microgravity tests. Also, the microgravity effect on the thermal performance of such PHPs can be assessed by comparing the present results with future microgravity data obtained in an experimental module aboard a sounding rocket.