Integrated Design Of Thermoelectric Generator For Internal Combustion Engine Waste Heat Recovery And Exhaust System

Only about one third of the energy generated by fuel combustion in internal combustion engines is converted into effective power output,and the rest of the energy is dissipated into the environment in the form of exhaust and cooling water.Recovery of waste heat from internal combustion engine is beneficial to improving the efficiency of internal combustion engine.In addition,the exhaust of internal combustion engine has great recycling value because of its high temperature and high grade.Thermoelectric technology is an ideal waste heat recovery technology because of its simple structure,stable operation and convenient maintenance.At present,the main problem of thermoelectric generator(TEG)is the low efficiency.Besides,the performance of TEG is also influenced by the pressure drop and increased weight for installing TEG in exhaust system.The pressure drop and increased weight will increase the power consumption of engine,and further affect the net output power of TEG.In this paper,the TEG is considered to integrate with the catalytic converter and muffler in the exhaust system.The hot side heat exchanger has both functions of purification and noise elimination,which is helpful to reduce the total pressure drop and weight of the exhaust system.Firstly,the integration of TEG and three-way catalytic converter(TWC)is studied.The thermal-electric model of thermoelectric module and the reaction kinetics model of catalytic converter are established.The integrated model is optimized through the coupled calculation of thermal-electric-flow-reaction to get both good performance of TEG and TWC.The results show that the catalyst carrier installed at the back of the heat exchanger can make the heat exchanger surface have a relatively uniform temperature distribution,which is conducive to improving the maximum output power of TEG;a proper number of modules can maximize the maximum output power of TEG,and too many modules not only reduce the maximum output power of TEG,but also affect the conversion efficiency of TWC;the guide body can improve the output power of TEG,and attention should be paid to balance on the pressure drop and the conversion efficiency of the catalytic converter when designing the guide body.Based on the optimized model,the net output power of the integrated TEG and the single TEG is compared.The integrated design can increase the net output power by 37%.Then the design scheme of thermoelectric generator with noise elimination function is explored.Based on Fluent platform,the evaluation method of noise attenuation effect is established.The transmission loss of original guide body type heat exchanger is calculated,and an improved design scheme of the baffle heat exchanger is proposed.The baffle structure enhances the heat transfer and divides the heat exchanger into several expansion chambers,which has a good effect of noise elimination.Several parameters of baffle heat exchanger were studied.The results show that optimizing the position of baffles can increase the output power of TEG and change the position of baffles can improve the noise attenuation of certain frequency noise;increasing the height of baffles can increase the output power of thermoelectric generator as well as the transmission loss;under the condition of optimizing the position of baffles,increasing the number of baffles can’t obviously improve the output power of thermoelectric generators,but increase the transmission loss of heat exchangers.