Analytical and experimental study of a thermoelectric generator system for low grade chimney waste heat recovery

This study presents an analytical model and module scale experimental assessment of a thermoelectric generator system for low grade waste heat recovery from an industrial chimney. The model couples the effective module properties, the thermoelectric energy balance, the hot and cold side heat sink paths and the electrical load, and is used to examine load resistance, thermoelement leg length, heat sink fin thickness and cold side heat rejection. A module scale bench experiment at a hot side temperature of 164 to 183 °C gave a measured peak output power of 0.354 W at a load resistance of 1.5 Ω, and the model reproduced the measured voltage, current and power with a power root mean square error of 16.4 mW, where the external conductances and the internal resistance were obtained by fitting the model to the measured power at the same fourteen load points. The module model built from the manufacturer data was checked separately against the manufacturer matched load curves. The model gave a maximum power of 0.328 W at 1.30 Ω and a maximum efficiency of 1.45 per cent at 1.39 Ω, with load resistance and leg length selected together. A plate fin heat sink analysis gave an optimum fin thickness of 0.76 mm with the fin height set by the optimum profile relation, and raising the cold side conductance from 0.276 to 2.0 W/K increased the modelled power to 1.13 W, identifying cold side heat rejection as the limiting path. Applied to a 9 m² active recovery area, the module results give a section output of 1.85 to 1.99 kW for the measured and modelled cases and 2.72 kW for the leg length design case, reported as a uniform boundary reference rather than installed field output.