Efficiency enhancement of an industrial-scale thermoelectric generator system by periodically inputting thermal power

Abstract

This paper discusses the practicality of transferring heat energy from exhaust waste gas produced by iron and steel factories to Dowtherm T, which is employed as a heat source of a thermoelectric generator (TEG) system. The electrical performance of an industrial-level TEG system when supplied with pulsed thermal power is optimized. Heated Dowtherm T is periodically pumped into an industrial-level TEG-based heat-to-electricity conversion system (i.e., TEG unit) to generate pulsed heat power. Twelve TEGs are used in the experiments; they are evenly separated and doubly sandwiched among three heat exchangers. The conversion efficiencies at duty cycles of 21% and 46% are measured and compared. The experiments show that pulsed thermal power yields better results than the steady-state power input in terms of the conversion efficiency under the same power input conditions; the thermal power of the lower duty cycle produces a greater enhancement of efficiency. Specifically, a maximum efficiency enhancement of 3.5× is achieved for a time period of 60min and duty cycle of 21%. These findings suggest that the thermal power input should be periodic rather than constant to greatly improve the electrical performance of an industrial TEG unit. The feasibility of employing periodic heating into waste heat recovery system is verified.