Additive-manufactured topology-optimized heat sinks for enhancing thermoelectric generator conversion efficiency

Thermoelectric generators (TEGs) are gaining great attention as a promising technology for waste heat recovery due to their ability to directly convert heat into electricity. However, their relatively low conversion efficiency limits widespread adoption. While efficient thermal management of TEGs is crucial to achieve high conversion efficiencies, less attention has been paid to this aspect thus far compared to materials development. Efficient TEGs require efficient heat dissipation on the cold side of TEGs, demanding careful heat sink design. In this study, a topology optimization model was developed to design air-cooled heat sinks specifically for TEG applications, incorporating both thermoelectric properties and geometric structure of TEGs. The optimized heat sink was fabricated using additive manufacturing, and its performance was experimentally validated. Compared to a conventional rectangular fin heat sink, the topology optimized (TO) heat sink significantly reduced thermal resistance across a wide range of pressure drops (6 Pa to 30 Pa), achieving a 33.5% reduction at a 12 Pa pressure drop. This led to a 44.7% increase in the output power of a commercial TEG. Despite a ~40% increase in power consumption, the TO heat sink resulted in a 21.3% improvement in conversion efficiency. This improvement is equivalent to a 27% increase in the device thermoelectric figure of merit (ZT). Numerical simulations revealed that the TO heat sink can enhance temperature uniformity on the cold side of the TEG, further contributing to performance gains. These findings highlight the effectiveness of heat sink topology optimization in enhancing conversion efficiency of TEGs.