Reconstruction of flow and temperature fields of exhaust gas flow for enhancing the energy harvesting performance of a thermoelectric generator

This study investigates the reconstruction of flow and temperature fields to achieve optimal energy transfer from exhaust gas to thermoelectric modules (TEMs). A robust three-dimensional numerical model incorporating multiphysics associated with thermoelectric generators (TEGs) was developed to analyze the detailed effects of field reconstruction via porous conditioners. Nusselt number analyses indicated that transverse field reconstruction reduced the thermal resistance between the exhaust gas and TEMs by 11.5%, enhancing the waste heat recovery performance. The cross-sectional temperature contours visualized the longitudinal field reconstruction and corresponding reheating of the TEMs. The key finding is that the field reconstruction effect begins at one TEM length before the porous conditioner and continues to the end of the exhaust gas channel, clarifying the optimal location of the primary conditioner. With the primary conditioner at the optimal location, the best pair location of a boost conditioner, whose porosity ranges 0.335–0.730, was obtained through coefficient of variation analysis and the net power output of the TEG. The results showed that harmonizing the primary and boost conditioners improved the net power output of the TEG by 9.3% and 25.7%, respectively, compared with the cases with only the primary conditioner and without any conditioner.