The Research Of Two-stage Thermoelectric Generator For Waste Heat Recovery Using High Temperature Exhaust Of Internal Combustion Engine

Thermal efficiency of internal combustion engine can be improved throughwaste heat recovery (WHR), while thermoelectric generator (TEG) is a promisingmethod to recover waste heat of ICE. The characteristics of exhaust gas, property andtypes of thermoelectric materials were analyzed, and then a two-staged TEG has beenproposed and established to improve the engine thermal efficiency based on the largetemperature difference of exhaust gas and the optimized working temperature ofthermoelectric material.Firstly, the thermoelectric materials of two-stage TEG have been decided. Atwo-stage TEG model has been built and verified. Based on the two-stage TEG model,the performance of single-stage and two-stage TEG were compared under differentambient conditions, including the effect of external resistance, different heat and coldsource temperatures and transfer coefficient in cold and heat sides. The results showthat heat source temperature has an important impact on the selection of TEGstructure; the two-stage TEG has a better performance than the single stage TEG at ahigh temperature source with large temperature difference.Then, the two-stage TEG structure is designed, including couple-level andcomponent-level. The main research of couple-level is the effect of thermocouplecharacteristics on the performance of two-stage TEG, including the length andcross-sectional area of thermocouple, thermoelectric material and the number ofthermocouples. It is shown that the effects of thermocouple nature are different onoutput power and conversion. The main research of componment-level lies in theselection of heat exchanger, the thermal ceramic, external resistance, the structure ofparallel and serial. The optimization working conditions of two-stage TEG can beobtained using exhaust gas and cooling water as heat and cold source.Through the optimization of structure and work conditions on two-stage TEG,we can see that it is an effective way to save energy and reduce fuel consumption andCO2emissions, which lays a good foundation on WHR system in ICE.