Energy and exergy analysis of a thermoelectric generator mounted between dual channels with corrugated and perforated fin inserts using a ternary hybrid nanofluid

Thermoelectric generators (TEGs) are increasingly recognized as a promising technology in energy harvesting applications, particularly for recovering waste heat from industrial plants via the Seebeck effect, which converts thermal energy into electrical energy. This study aims to address the challenge of TEGs' relatively low thermal conversion efficiency by investigating methods to maximize heat exchange at the extremities of the thermoelectric generator, thereby enhancing electricity production. The finite element method is adopted to solve the governing multiphysics equations of a three-dimensional thermoelectric generator, consisting of 128 pairs of bismuth telluride semiconductor elements, mounted between hot and cold channels through which a Cu-Al₂O₃-MWCNT/water ternary hybrid nanofluid flows. The present study examines the integration of three distinct fin geometries (zigzag, rectangular, and wavy) in the hot and cold channels. Key factors, including the amplitude of corrugation (1–5 mm), the number of corrugations (1–5), and the Reynolds number (200–1500), are evaluated to identify the optimal energy and exergy efficiencies of the TEG module. The results show that increasing the amplitude and number of corrugations on the fins greatly enhances both electrical production and thermal conversion efficiency of the TEG. Maximum power improvement occurs with a 5 mm amplitude and a frequency of 3 for zigzag and wavy fins, producing 0.452 W and 0.451 W, respectively. These fin designs increase electrical power production by 33% and 32.3% compared to a finless hot channel, while the rectangular fin improves it by 22%. Additionally, thermal conversion efficiency rises by 15% for zigzag, 14.9% for wavy, and 10% for rectangular fins. A slight increase in the TEG's exergy efficiency is observed when three fins are added to the hot channel; however, this also raises entropy generation. Furthermore, as the Reynolds number increases, the TEG's power generation, thermal conversion efficiency, and exergy efficiency all rise significantly, though this is accompanied by increased pumping power penalties. Finally, inserting three additional fins in the cold channel at optimal locations improves the TEG's output power by 67.3% for the zigzag, 65.8% for the wavy, and 50% for the rectangular configurations. The corresponding thermal conversion efficiency improvements are 27% for the zigzag, 24% for the wavy, and 24% for the rectangular configurations.