Experimental investigation of waste heat recovery of thermoelectric generators with temperature gradient. (April 2022)

• Record Type: Journal Article
• Authors: Ma, Xiangrong; Hu, Shenhua; Hu, Wuyuan; Luo, Yuze; Cheng, Hao
• Is Part Of: International journal of heat and mass transfer. Volume 185(2022)
• Publication Date: 2022-04
• Subjects: Waste heat recovery -- Temperature gradient -- Module array configuration -- MPPT -- Thermal resistance; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2021.122342
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Fully assess an air-to-liquid waste heat recovery system with temperature gradient. The effect of inlet temperature, mass flow rate, insert and electrical connection type on the performance of the TEG were investigated. A new power system was proposed based upon experimental results and MPPT techniques. Abstract: In gas-to-liquid thermoelectric generators (TEG), the stream-wise gas temperature drop on hot side is inevitable and then the problem of decreased power output appears due to the inhomogeneous temperature gradient distribution on heat exchanger surface. Several factors, such as inlet temperature, mass flow rate, will affect the performance characteristic of waste heat recovery. In order to fully assess a waste heat recovery system with temperature gradient, a thermoelectric experiment platform composed of 32 TEGs was built. The effect of inlet temperature, mass flow rate, turbulating insert and connection type on the performance of the TEG were investigated in detail. The inlet temperature and mass flow rate were varied from 150 0 C and 12 kg/h to 300 °C and 24 kg/h, respectively. Five different TEG array configurations were formed using series, parallel and combination connections to form one source or several sources to provide electrical energy. Based upon experimental results and maximum power point tracking (MPPT) techniques, a new power system was proposed. Compared to the common connection type (32 TEGs in series), the net output power of the new system could enhance by 19–67% without increasing pumping power and air loss power. Moreover, with increasing the load resistance, the output current will decrease, which leads to an increase in the temperature difference across the TEG and the thermal resistance. In our experimental condition, the maximum net efficiency was nearly 0.7%. Finally, the convective heat transfer coefficient of inner wall of heat transfer exchanger was compared with the value calculated by Hausen's correlation, and most of the results were within 30%.