Pulsating Heat Pipe Laboratory Tests for a Microgravity Sub-Orbital Experiment

In the last decades, satellites and spacecraft have become more sophisticated, and consequently, the onboard electric/electronic systems have increased their demand for more efficient thermal control. Considering that most technologies for the thermal management of electronics in space applications involve two-phase devices, many research groups concentrate efforts on improving the performance of heat pipes and similar devices under microgravity conditions. In this context, a flat plate pulsating heat pipe (PHP) for the thermal management and heat dissipation of electronics, such as those aboard satellites and spacecraft, was specially developed for future tests aboard the VSB-30 sub-orbital rocket in the Igaratá Mission, within the microgravity program of the Brazilian Space Agency (AEB). A two-phase device contains 26 round cross-section channels. The PHP thermal performance of ethanol and water was compared in order to select the best working fluid for the microgravity experiment. Also, two heat sinks were tested: a water-cooling bath for the thermal characterization of the PHP and a copper box with a PCM (dodecahydrate dibasic sodium phosphate) qualifying as heat storage for tests aboard the sub-orbital rocket. According to the experimental results, ethanol is a better working fluid for such an experiment, as it meets flight requirements and presents an early start-up, saving battery power. Besides, the proposed PCM heat sink showed a satisfactory thermal performance, being an efficient option for experiments aboard sounding rockets, as it allowed a proper PHP operation. As the main result, the proposed experimental module was validated on ground tests, including the PHP and the heat sink, being ready for the next missions.