Theoretical Analysis Of Semiconductor Thermoelectric Generator Using Exhaust Gas Of Vehicle As Heat Source

In recent years, with a series of polices and measures of energy conservation andemission reduction implemented in China, more and more attention has been attractedin these areas nationwide. China has become a big automaker that energyconservation and emission reduction in auto industry and auto itself are becoming animportant topic of research. Fuel economy of engine is a important target ofenergy-saving of auto, as the technology of engine is quite mature, it is dififcult toimprove energy-saving of auto simply from improving performance of engine.Considering there is a lot of high temperature heat energy in exhaust gas of auto thatcan be transferred into electric energy by means of semiconductor thermoelectrictechnology and stored into storage battery, which is then re-supplied the auto electricequipment or constitute part of hybrid electric vehicle with motive power, it will be ofgreat significance on energy conservation and emission reduction in auto field. Basedon Fouir’ers law and Seebeck effect, this paper presents a mathematical model ofThermoelectric Generator (TEG) device using the exhaust gas of vehicles as heatsource. The model simulates the impact of relevant factors including vehicles exhaustmass flow rate, temperature and mass flow rate of different type of cooling fluid,convection heat transfer coeiffcient, height of PN couple, ratio of external resistanceto internal resistance of circuit on the output power and eiffciency. The results showthat using water-cooling is much better than air-cooling, and the output power andefficiency increase significantly by changing convection heat transfer coeiffcient ofhigh-temperature-side than that of low-temperature-side. Meanwhile we find that withthe change of the height of PN couple, there is a peak value of the output power whichdecreases when decreasing the thermal conductivity of PN couple and increases whenincreasing the Seebeck coeiffcient and electric conductivity of material. We alsoconclude that the maximum output power and eiffciency of TEG appears whileexternal resistance is bigger than internal resistance which is different from thecommon circuit. And with the increment of ZT, the maximum value moves toward thedirection of increasing ratio of external resistance to internal resistance. We propose anew idea that combing with phase-change technology which has huge capacity of heat absorption and release. It is expected hopeful to achieve a big improvement in output power and efficiency of TEG device by changing our experiment design accordingly.Finally, based on the current theoretical inadequacies, recommendations for improvement are proposed and the follow-up studies of the subject project are suggested.