Numerical investigation on optimizing the couple geometry of a thermoelectric generator under various thermal conditions

In the quest for effective thermal energy recovery and thermoelectric generation of electricity, thermoelectric devices stand out and offer a promising pathway as compact, solid-state energy harvesters capable of converting temperature gradients directly into electrical power, scalability, and environmental compatibility. This study presents a detailed finite element analysis using COMSOL Multiphysics to optimize key geometric and thermal parameters affecting thermoelectric generator (TEG) performance. The investigation begins with a single thermoelectric leg (TEL), varying its dimensions (1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm), cross-sectional areas (0.25 × 0.25 mm 2 , 0.5 × 0.5 mm 2 , 0.75 × 0.75 mm 2 , and 1.0 × 1.0 mm 2 ), conductor layer thickness of 0.125 mm, and insulating layer thickness of 0.25 mm. Simulations were carried out under hot-side temperatures 350 K, 400 K, 450 K, 500 K, and 550 K), with the cold side (T C ) maintained at under matched load conditions. As well as the couple number effect on the thermal and electrical performance of thermoelectric modules was examined at different operating and design conditions. The optimal configuration leg has a length of 1.5 mm and a cross-sectional area of 1.0 × 1.0 mm 2 . The outcomes showed the highest electric current of 1.2 A and a power output of 0.069615 W. The output power increases with the increase in the number of thermoelectric pairs under all the studied conditions, which proves an effective and dominant role in enhancing the performance of the thermoelectric unit. The simulated results demonstrated excellent agreement with existing literature, showing error margins of less than 3%, thereby validating the model. The novelty of the current study lies in its consistency, based on leg-level optimization and full-module performance analysis under both fixed and variable substrate configurations. In addition, the numerical simulations were conducted for both imposed heat flux and constant temperature difference, allowing uniform modeling standards across all cases. This work provides critical insights into how geometric precision and thermal loading affect the efficiency of TEGs, offering valuable guidelines for the future design of microscale and industrial-grade thermoelectric energy harvesters.