No abstract

In this study, the hot-side heat exchanger (HHE) thermal uniformity in the thermoelectric generator unit (TGU) is enhanced by optimizing the muffler's guide fins. Three parameters of the guide fins (i.e., fin gap δ, fin angle θ, and fin position x) are proposed. Various muffler models with different guide fins' geometry are numerically investigated to achieve the optimal set of δ, θ, and x parameters by assessing the exhaust flow uniformity of the HHE. The optimal muffler model is then simulated to compare with the nonoptimal muffler model. The HHE's thermal uniformity of these two models is experimentally investigated under various testing conditions. The results show that the parameters of δ and θ significantly affect the exhaust flow uniformity of the HHE, whereas the variable of x only has a minor influence. Thanks to the optimal values of δ, θ, and x, the exhaust flow uniformity increases 11.23% on average compared to the nonoptimal model. Consequently, the thermal uniformity is improved, and the maximum temperature difference on the HHE of the optimal model is 35% lower on average than that of the nonoptimal model.

Following the development of the muffler with the optimal guide fins (MOGF) in the companion paper (Part 1), this study optimizes the muffler outlet in terms of structure and geometry to further improve the thermal uniformity of the hot-side heat exchanger (HHE). Two outlet structures and two outlet geometry parameters (i.e., outlet angle φ and outlet position y) are proposed. The exhaust flow uniformity of HHE serves as an assessment criterion in numerous computational fluid dynamics simulations to determine the optimal outlet structure and optimal values of φ and y.The outlet of the MOGF is then modified based on the simulation results to create the muffler with the optimal guide fins and outlet (MOGFO). Various experiments on the MOGFO are conducted to verify the simulation results and evaluate the improvement of the HHE's thermal uniformity. The simulation results prove that the optimal outlet improves the exhaust flow uniformity by 1.78% on average compared with the original outlet. In experiments, the combination of optimal muffler's outlet and optimal muffler's guide fins on the MOGFO raises the thermal uniformity of HHE by an average of 22.71% and 50% compared with the MOGF and the muffler model with nonoptimal guide fins and outlet in Part 1, respectively.