Thermoelectric generator for industrial gas phase waste heat recovery

A technical solution recycling exhaust gas sensible heat based on thermoelectric power generation is proposed by using finite time thermodynamics. The effects of some key parameters such as exhaust gas inlet temperature, exhaust gas and cooling water heat transfer coefficient on the optimum length of the thermoelectric elements are analyzed. It is found that the gas temperature drops rapidly because of the small specific heat of the exhaust gas. Enhancing the heat transfer of gas can effectively improve the power, but not the efficiency. Exhaust gas inlet temperature and transfer coefficient have significant effects on the optimal thermoelectric element length. Due to the highest hot surface operating temperature limit 200 degrees C, the optimal length of the thermoelectric elements is about 2 mm. About 1.47 kW electrical energy can be produced per square meter and the conversion efficiency of 4.5% can be achieved for exhaust gas at 350 degrees C. The payback period of the waste heat recovery device is about 4 years for the price and performance of thermoelectric products made in China. (C) 2017 Elsevier Ltd. All rights reserved.