Integrated Design Study Of Internal Combustion Engine Exhaust Heat Transfer And Aftertreatment

With China’s goal of reaching peak CO₂ emissions by 2030 and striving to achieve carbon neutrality by 2060,the energy-saving requirements of internal combustion engines（ICEs）,still the most important power machinery in the transportation sector,have become more urgent.At the same time,the deepening awareness of environmental protection and ecological civilization has also prompted governments to impose increasingly stringent regulations on vehicle emissions.Waste heat recovery（WHR）technology can effectively utilize the waste heat energy of ICEs,thus improving the overall energy efficiency of ICEs.However,the exhaust gas heat exchanger,a necessary equipment for waste heat recovery,has space and functional interference with the exhaust gas aftertreatment system with many components.Causes the exhaust back pressure increase,the vehicle’s weight increases,aftertreatment performance decreases and other effects.Not conducive to the practical application of bottom cycle waste heat recovery technology in motor vehicles.In order to realize the lightweight and compactness of the waste heat recovery and aftertreatment system,this paper integrates the design of exhaust gas heat exchange and aftertreatment,and conducts performance analysis and optimization studies for them.A one-dimensional transient model of the exhaust pipeline containing the heat exchanger was developed.The layout study of heat exchanger and aftertreatment equipment was carried out,and the logical relationship between the exhaust gas heat exchanger and aftertreatment equipment was analyzed and summarized.Proposes that the exhaust gas heat exchanger has the potential to significantly reduce the pressure drop in the exhaust system,but due to the decentralized arrangement of the components,the optimum performance of each cannot be achieved.Accordingly,the idea of integrating the exhaust gas heat exchanger with the key components of the post-treatment system into the design is proposed.Three types of integrated exhaust gas layer aftertreatment-heat exchanger configurations are also proposed.In this paper,the exhaust aftertreatment-heat exchange configuration is simplified into sub-channels,and a joint numerical simulation model of three-dimensional flow,heat exchange,nitrogen oxide（NO_X）catalytic conversion,and particle trap is developed for it.Based on this simulation model,the heat transfer and aftertreatment performance of the three Types of structures are analyzed.The effect of setting porous media layer at the heat-conducting spacer on the heat transfer and aftertreatment performance was also analyzed.The results show that the rectangular porous wall surface and the W-Type porous wall surface have better heat transfer performance,but the aftertreatment performance is poor.The porous media layer at the spacer can improve the heat transfer performance,but has a greater adverse effect on the post-treatment.According to the results of the analysis,the rhombic porous wall surface with heat transfer performance and aftertreatment performance are selected as,and the pressure drop analysis and optimization are carried out.An integrated device is designed based on the sub-channel scheme.A comprehensive evaluation method for the integrated configuration with the functions of exhaust gas heat exchange,catalytic conversion,and particle trapping is proposed.The integrated device was further analyzed and optimized from the perspective of thermal conductivity.Compared with the original system with the same performance,the final optimized design device reduces the total volume by 58.7%,which has a very obvious compactness advantage.