Numerical and Experimental Study on Performance of a Low-Backpressure Polyhedral Thermoelectric Generator for Waste Heat Recovery

Optimized fin arrangement and dimension of heat exchanger can improve the maximum output power of thermoelectric generator (TEG) system which converts the wasted heat into electricity with thermoelectric modules (TEMs). Considering that the geometric symmetry contributes to the temperature uniformity improvement and convenient TEMs arrangement, a low-backpressure TEG system based on a polyhedral-shape heat exchanger was developed. To assess the effect of inner topology and fin parameters on the heat transfer and output power of the TEG system, a realizable k-ε turbulence based numerical model was established and validated to perform numerical simulations. The results demonstrate that increasing fin length, fin width and fin intersection angle are beneficial to the average surface temperature, temperature distribution uniformity and maximum output power of the TEG system. Moreover, decreasing fin spacing distance contributes to the enhanced average surface temperature and maximum power of TEG system, and has insignificant effect on its temperature uniformity. The inserted fins with optimal length, width, intersection angle and spacing distance enhance higher output power, whereas result in increasing backpressure. The maximum difference between the experimental and simulation results is 3.2%, which validates the feasibility of the established numerical model. It also provides a theoretical reference to the optimal design and performance analysis of low-backpressure TEG systems used in automobile exhaust heat recovery.