Computational and experimental investigation of thermoelectric generators in series-parallel configurations under variable resistive loads and temperature gradients

Thermoelectric generation is a potential technology for waste heat recovery, however, increase in the internal resistance is one of the key parameters limiting its utilization for scalable applications. Previous research in this domain is limited to the thermoelectric elements and modules. Current research focuses on the performance evaluation of thermoelectric generators under variable resistive loads and temperature gradients in different configurations. Computational modelling of the thermoelectric generator has been performed using fully coupled steady-state model in conjunction with experimental research to validate the results. Results were acquired under varying temperature gradients and resistive loads between 1Ω and 30Ω and extended up to 40Ω for eight modules in series. The system is analyzed experimentally through natural convective cooling for variable resistive load maintained at constant temperature, and the reverse scenario is also considered. The maximum power generated from a single thermoelectric module is 1.69W at 5Ω resistive load. This value corresponds to the temperature difference of 100°C and surpasses the experimental value by 6.29%. The study computationally evaluates thermoelectric performance of two, four, and eight modules in both series and parallel arrangements. The power output for eight modules configured in series, parallel, and hybrid arrangement was measured as 13.53W, 12.60W, and 13.55W, respectively, and efficiency was determined as 3.79%, 3.77%, and 3.84% respectively. The comparative results highlight optimal performance of thermoelectric generators in series & parallel hybrid arrangement. Study represents low grade waste heat recovery potential from coal fired power plants and oil and gas sector.