Space-based experiments show that wax-filled heat sinks keep electronics cooler for longer

An interdisciplinary research team, including Mickey Clemon, professor of mechanical science and engineering at Grainger University’s Faculty of Engineering at the University of Illinois at Urbana-Champaign, is investigating how heat sinks are cooled by conducting experiments on satellites currently orbiting the Earth.

“The university-sponsored satellites have a very low success rate of putting it in space, so we’re very pleased that we put it in space and our system works,” Clemon said.

The team has published recent findings from ongoing research. “We investigate the performance of heat sinks for satellite avionics thermal management, from ground level testing to space-like conditions.”

Thermal management of electronic devices in space poses a unique set of challenges due to the generation of waste heat and the lack of convective cooling in vacuum. Therefore, systems operating in space must either effectively emit radiation or limit more prohibitive computing.

To address these challenges, the team developed a heat sink containing wax-based phase change materials that melt within the normal operating temperature range of electronics. Melted wax stores energy more quickly and allows electronic devices to cool for longer.

“We’re testing different duty cycles and cooling regimes using the fixed heat sink we put there,” Clemont said. “The idea is that this will inform the design and operational sequence of other electronic devices and space computing.”

The team deployed the test rig on Cubesat, a miniaturized satellite consisting of 10 cm cubic modules on each side. The satellite was launched in August 2024 (see the working dashboard here) and has several payloads, including heat sinks, as part of the Waratar Seed mission.

“We alternate our experiments with other payload experiments,” Clemon said.

The results for the team so far are promising. For one, melting wax greatly increases the time that electronic devices can operate within safe temperature ranges. Furthermore, the microgravity environment does not affect the orientation of the wax in the heat sink.

“We have developed some simplified models to predict the performance of these heat sinks, which could provide the first direction for designers to test their designs rather than building something and physically testing them,” Clemont said.

With more experiments planned, the team’s exploration in space continues.

“Our orbit is about 90 minutes, so we have sunlight exposure times and non-sun exposure times,” Clemon explained. “We have a fundamental heating profile from the sun itself and we want to investigate the effect on computing time available on electronic devices.”

First author, Larissa Sueza Rafa, studying at Sydney Institute of Technology, is a PhD from Clemon. Student. Second author, Matt Ryall, represents the team’s industry partner, Mawson Rovers. Other authors include Professor Iver Cairns of the University of Sydney and Associate Professor Nick Bennett of the Institute of Technology of Sydney.