Performance evaluation and improvement of thermoelectric generators (TEG): Fin installation and compromise optimization

•The performance of a thermoelectric module (TEM) with/without fins is explored.•A TEM’s performance with 78 square pin fins is higher than that with plate fins by 24.14%.•The compromise between heat transfer and material cost occurs at 54 square pin fins.•The net output power of a TEM with square pin fins is up to 34.06 folds that without fins.•Square pin fins can significantly increase output power and reduce material costs. How to improve the performance of thermoelectric generators is an important issue to recover waste heat and convert it into green power, which is conducive to practicing net-zero carbon dioxide emissions. The heat transfer and power generation of a thermoelectric module (TEM) under the influence of fin installation is investigated by three-dimensional fully numerical simulations where vehicle exhaust waste heat is harvested. This study considers a TEM in a hot channel without fins as well as with plate fins and square pin fins, while a cold channel is used to cool the TEM. The results show that installing plate fins or square pin fins can drastically intensify waste heat harvest, and the optimal number of square pin fins is 78 which increases the output power of the TEM by 24.14% compared to the plate fins. A compromise method in terms of heat flow rate ratio and heat flow rate ratio per unit area of square pin fins is conducted, which simultaneously considers the TEM’s output power and material cost. As a result, it is found that the optimal number of square pin fins is 54. The influences of the temperature and mass flow rate of the hot fluid on TEM performance are also evaluated, and the results indicate that the former has a pronounced impact whereas the latter is relatively unimportant. Installing more square pin fins gives rise to a higher pressure drop. Nevertheless, the net output power of the TEM increases with increasing the number of square pin fins and the highest value occurs at 78.