Experimental study of energy utilization effectiveness of thermoelectric generator on diesel engine

This study was devoted to investigating the energy utilization of a thermoelectric generator (TEG). Key factors governing the power generation characteristics of the TEG-the power output, system resistance, and conversion efficiency-are systematically analyzed under various engine operating conditions. The effects of heat rejection conditions on the energy utilization by the TEG are also examined. Experimental results show that a slight coolant temperature reduction of 10 K increases the TEG power output by up to 33.7%, increasing the short-circuit current. The coolant temperature reduction also causes more than 34.8% improvement in the conversion efficiency. Contour maps for the power output and conversion efficiency are proposed as functions of the engine load and speed. A maximum power output and conversion efficiency obtained are ∼125.7 W and ∼3.0%, respectively. In contrast to the coolant temperature effect, a change in the coolant flow rate has a relatively insignificant effect on energy utilization: the power output variation is only 6.8%-8.5%. The TEG design effectiveness is evaluated by analyzing the flow of exhaust gas energy. The analysis shows that a relatively large portion of exhaust gas energy (37.4%-47.1%) is lost to the environment instead of being used for power generation by the TEG.