Experimental investigation of energy storage and reuse of recovered waste heat based on thermoelectric generation

Abstract

Heat energy may be converted into electric energy via a thermoelectric generator (TEG). It is an effective method of recovering and utilizing low-grade energy. However, the output voltage of a TEG is typically too low for direct applications. A waste heat recovery system based on thermoelectric generation was developed to convert waste heat energy into electric energy for energy storage and to operate an LED car light. The variability of thermal-electrical conversion and energy distribution in different stages of the system, as well as the response characteristics of the LED car light under heating temperature fluctuations, are investigated experimentally. The performance of different energy storage components on the time-dependent output characteristics of the light is also analyzed. The results indicate that the energy storage elements can store the energy derived from waste heat, power an LED car light independently, and buffer the power fluctuations caused by the heat source's temperature variation. The energy distribution ratio differs for different energy storage components. Lithium batteries have a high energy density and can store more electricity. The cold start of the LED car light is quick, and the illumination time is longer, but it requires more time to obtain a full charge. The supercapacitor has a sluggish cold start but a high charge and discharge speed, reducing voltage fluctuations when the waste heat recovery system is turned on for a short period. In addition, the system may be utilized to power additional low-power devices.