Increasing waste heat recovery performance of a hexagonal thermoelectric generator with microchannels

In this work, a hexagonal thermoelectric generator with novel fins is proposed to improve the overall thermoelectric performance. The diverging design and microchannels are introduced into the traditional fin structure to achieve high heat transfer efficiency and low pressure drop. Additionally, a fluid-thermal-electric multiphysics numerical model of the hexagonal thermoelectric generator is established for optimizing parameters and evaluating the performance of the novel fins. Research indicates that reducing the spacing and width of microchannels in the novel fins can not only increase the output power of the hexagonal thermoelectric generator but also decrease backpressure losses, except that backpressure losses increase with the decrease of microchannel width. To maximize net power, the optimal values of microchannel structural parameters are determined as w = 0.25 mm and d = 0.25 mm within the 0–40 g/s mass flow rate range. Finally, a comprehensive comparison is conducted among the novel fins, diverging fins, and traditional fins. The comparison results show that the hexagonal thermoelectric generator with non-microchannel diverging fins has lower efficiency and net efficiency than the hexagonal thermoelectric generator with traditional fins. The introduction of microchannels compensates for this deficiency and comprehensively improves the overall performance of the hexagonal thermoelectric generator. Compared to the traditional structure, the output power, net power, efficiency, net efficiency, and temperature uniformity coefficient of the hexagonal thermoelectric generator with novel fins showed an average improvement of 17.01 %, 10.81 %, 6.41 %, 1.25 %, and 2.58 %, respectively.