Laryssa Sueza Raffa, Matt Ryall, Nick S. Bennett, Lee Clemon
Maintaining satellite electronics within their maximum allowable operating temperatures is crucial for long-term reliability, yet increasingly power-dense payloads and miniaturized satellites introduce severe challenges. To meet the demand for efficient thermal management, this study leverages advances in additive manufacturing and explores triply periodic minimal surface (TPMS) heat sinks with phase change material (PCM) for space use, a growing area but with limited research. As part of the design development of the University of Technology Sydney’s payload Matilda, this work examined how geometry, material composition, and orientation influence the performance of PCM-based thermal management modules. Five heat sink designs were investigated: hollow, gyroid, I-graph-Wrapped Package-graph (IWP), swirl, and radial plane fins. The heat sinks were 3D-printed from titanium and stainless steel, filled with paraffin wax PCM, and tested under vacuum at two power levels. Key parameters such as internal surface area and mass were analysed. Results show that, although material thermal conductivity influences temperature, design-dependent factors such as total metallic mass and internal structure distribution dominate heat dissipation. The gyroid achieved the lowest temperatures, though at the cost of increased mass, while mass-normalized performance identified the IWP lattice and radial-finned designs as most efficient. A mass-matched comparison of these two revealed nearly identical performance despite 27% difference in internal surface area, underscoring the role of total mass and internal geometry distribution. Orientation and initial PCM position had minimal influence, with less than 4 °C variation. These findings demonstrate that thermal performance is heavily affected by material properties, total mass, and structure distribution, with geometric complexity offering secondary benefits, and orientation and PCM position yielding minimal returns.