Performance optimization of a segmented converging thermoelectric generator for waste heat recovery

In this work, a segmented converging thermoelectric generator is proposed and optimized by designing a variable converging angle in each segment of the heat exchanger. A mathematical model of thermoelectric generator is developed to determine the corresponding converging angles. Also, the effects of air temperature and mass flow rate on the segmented converging structure are explored. Results show that the output power of thermoelectric generator can be apparently improved by using the segmented converging heat exchanger that can make the temperature differences of thermoelectric modules in all segments approximately identical. Compared to the conventional one, the output power can be increased by 12.5% at the air temperature of 500 K and air mass flow rate of 20 g/s, where the converging angles of the segments of heat exchanger are 0 degrees, 2 degrees, 1 degrees, and 1.8 degrees respectively. It seems that the converging angles between the segments change like a sine wave, and the wave range rises with increasing the air temperature and decreasing the air mass flow rate. In addition, the backpressure power loss induced by the segmented converging heat exchanger is lower than the conventional plate-type one due to an apparent decrease of the head loss of outlet cover. This novel optimization structure of the heat exchanger can provide a global performance improvement for the thermoelectric generator system.