Numerical Investigation on Thermoelectric Power Generator With Gradient Plate-Fin Heat Exchanger

The multiphysics numerical model for the thermoelectric power generator (TEG) is established. The influence of heat exchanger is fully considered. The characteristics of temperature distribution, pumping power and thermal conversion efficiency of the TEGs with different fin structures are studied at Reynolds number from 1000 to 10000. Three types of fins including the full-height plate fin (Fin-1), gradient fin emphasizing downstream enhancement (Fin-2), and gradient fin emphasizing upstream enhancement (Fin-3) are compared and analyzed. The result shows that, with a constant length-to-height ratio of hot-side channel and coverage rate of thermoelectric materials, the output power and conversion efficiency of the TEG show a quadratic changing trend with the flow rate, and the optimal matching flow rate makes the system have the best power generation performance. The full-height plate fin is sensitive to the change of flow rate. With the increase of flow rate, the pressure loss increases, resulting in no benefit for the net output power and conversion efficiency. In comparison, the heat exchanger with gradient fin can generate positive benefits in a larger range. The heat exchanger with Fin-2 has the best streamwise temperature uniformity, but the local thermal resistance along the channel is the largest. Based on the performance of the local thermal resistance distribution and pumping power consumption, the TEG system with Fin-3 has the highest net conversion efficiency, so the synthesis factor of the local thermal resistance distribution and pumping power is the key to the optimal design of heat exchanger in TEGs.