Analysis of thermoelectric generation characteristics of flue gas waste heat from natural gas boiler

• Published in: Energy conversion and management Vol. 148; pp. 820 - 829
• Main Authors: Zhao, Yulong, Wang, Shixue, Ge, Minghui, Li, Yanzhe, Liang, Zhaojun
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 15.09.2017; Elsevier Science Ltd
• Subjects: Boilers; Electric power generation; Electricity generation; Enthalpy; Exhaust gases; Flue gas; Heat generation; Heat of vaporization; Heat transfer; Heat transfer coefficients; Humidification; Latent heat; Natural gas; Performance enhancement; Performance optimization; Sensible heat; Temperature effects; Thermal energy; Thermoelectric generation; Thermoelectric generators; Thermoelectric power generation; Thermoelectricity; Waste heat; Waste heat utilization; Water vapor; Wet flue gas; Waste heat utilization; Performance optimization; Natural gas; Wet flue gas; Thermoelectric generation
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2017.06.029

•A model was established to investigate the TEG characteristics of wet flue gas.•The TEG performance of wet flue gas was different from that of dry flue gas.•Gas humidification was proposed to improve the TEG performance of wet flue gas.•Intermediate humidification was proposed for the high temperature wet flue gas.•The optimal intermediate humidification temperature was presented. For the large quantity of water vapor present in the exhaust gas of natural gas boilers, the waste heat of the flue gas is not only determined by the sensible heat, but also by the latent heat of condensation. In this study, a generation model was established in order to investigate the thermoelectric generation characteristics of the wasted flue gas heat. The calculated results show that the characteristics curves can be divided into a sensible heat generation region and a mixed power generation region, with the power generation performance of both regions having different characteristics. Considering that the heat transfer coefficient of wet flue gas is higher than that of dry flue gas, this paper proposes to improve the performance of the generator through gas humidification, which not only improves the maximum output power, but also reduces the area of the thermoelectric module required for maximum power output. In addition, a thermoelectric power generation system created by intermediate humidification of flue gas, and which can fully utilize high-temperature flue gas and improves the power performance of thermoelectric generators at a lower temperature is presented. An optimum intermediate humidification temperature that results in maximum output power at the smallest corresponding module area is also determined.