Optimal Thermal Conditions for Maximum Power Generation When Operating Thermoelectric Liquid-to-Liquid Generators

Abstract

Thermoelectric modules (TEMs) embedded in heat exchangers provide a means of converting industrial waste heat into electrical power for local electrical energy needs. Due to the nature of the thermoelectric effect, a generator’s efficiency is dictated by a balance in its ability to act as a heat exchanger and its ability to maintain a high temperature difference. The present system-level study investigates the thermal conditions required for optimal power generation when using TEM embedded heat exchangers. From the analytical results, optimal thermal operating conditions are scrutinized, and a model is developed providing insight into the balance between heat transfer and temperature differential for optimal thermoelectric generator (TEG) design. It is demonstrated that under constant temperature difference, a heat exchanger effectiveness of 0.5 is an optimal compromise between heat flux and temperature difference for thermoelectric power generation. This criterion is universally applicable to TEGs as it relies solely on basic heat transfer and thermoelectric equations. Numerical simulations confirm that constant temperature difference along the length of the generator is achievable using tabulated inserts. A generator’s efficiency and power output are analytically solved and compared to the experimental results.