Experimental study on thermoelectric generators with gas heat source: Thermoelectric performance, exergy analysis and economic assessment

The utilization of high-temperature gases such as industrial waste and automobile exhaust as heat sources in thermoelectric generators (TEGs) has been widely adopted. This study experimentally examines the performance of a generator under various gas parameters and conducts exergy and economic analyses. Results reveal that enhancements in both the thermoelectric efficiency and resistance power consumption of the generator correlate with increasing gas flow rates and temperatures, presenting a greater proportion of resistance power consumption at lower flow rates. The generator is highly sensitive to the flow rate with respect to the temperature and voltage uniformity coefficients, yet the overall variation remains within 10 %. Exergy loss in gas heat transfer contributes to more than 50 % of the total exergy loss, whereas the heat transfer exergy loss in the module gradually increases with increasing gas flow rates and temperatures. An economic assessment of a TEG involves a cost‒benefit coefficient analysis, and the critical module price helps determine the necessity of employing a TEG for waste heat recovery from gas. For low-temperature, low-flow-rate gas, improving system economics can be achieved by reducing the heat exchanger thermal resistance. The insights from this study offer valuable guidance for the effective utilization of waste heat recovery from gases.