Configuration optimization of the segmented modules in an exhaust-based thermoelectric generator for engine waste heat recovery

Thermoelectric generators have gained extensive attention for the waste heat recovery of internal combustion engines. This work develops a three-dimensional numerical model of a thermoelectric generator (TEG) system used for the engine waste heat recovery. Using presented model, the heat exchanger with thinner wall thickness and moderate inlet dimensions is considered in this study to reduce the negative effects of weight increment and back pressure firstly. And then, the performance of two modes with different structures and configurations of thermoelectric modules (TEMs) are compared. In the mode of single-TEMs, segmented structure is adopted to match the large temperature gradient in the radial direction and there is a 13.4% increase of maximum output power compared with the original one. The TEG system with the mode of multi-TEMs proves to be more effective in waste heat recovery. The maximum output power in this mode is 78.9 W and there is an improvement of 30.8% compared with the original model. Finally, extended surfaces/fins in the heat exchanger can enhance the heat transfer and improve the temperature uniformity effectively. In addition, the fins also alter the optimal configuration of TEMs and further increase the maximum output power to 89.7 W.