Optimization of the thermal regime of thermoelectric generators in waste heat recovery applications

A thermoelectric generator is a device, which directly converts heat to electricity. These generators have been receiving renewed interest in recent years in a wide range of applications such as domestic wood heating, remote area power generation, automotive applications and power supply in interplanetary space flights. Applied as waste-heat recovery systems (WHRS), these generators can reduce fuel consumption and greenhouse gases such as carbon dioxide in stationary and mobile power plants. A pilot study of the applicability of thermoelectricity to waste-heat recovery from the exhaust gases of a small-scale steam boiler is presented. The steam boiler is used as the heat source for the low temperature WHRS of a single thermoelectric module (TEM). Two main types of heat sinks are used operating under various conditions, providing the necessary cold side temperature and hence the temperature gradient through the TEM. Both the energy input to the WHRS and the cooling flow rates of air and water are controlled to determine the effect on the electrical power output. The paper will experimentally investigate the thermal regime of assorted heat sinks functioning under various circumstances to establish the optimum operating conditions to achieve maximum power outputs from the WHRS. Further work is planned to estimate the thermal contact resistance at various interfaces in the system with different electrical insulators.