Analysis On Coupling Characteristics Of Diesel Engine Exhaust Integrated Aftertreatment System

In the fields of transportation and engineering machinery,diesel engines are widely recognized and applied for their advantages such as high thermal efficiency,strong power,and reliability.However,NOx,PM,CO,HC and other pollutants emitted by diesel engines will also cause serious air pollution.The off-engine aftertreatment technologies for reducing pollutants from diesel engine exhaust include:Diesel Oxidation Catalyst?DOC?,Diesel Particulate Filter?DPF?,Selective Catalytic Reduction?SCR?,Ammonia Oxidation Catalyst?AOC?,etc..However,relying solely on a certain aftertreatment technology makes it difficult to meet increasingly stringent emission regulations.Therefore,the use of integrated aftertreatment systems has become a necessary choice.However,when the integrated aftertreatment system is adopted,the purification effect of the integrated aftertreatment system on the exhaust gas of the diesel engine and the mutual coupling between the various after-treatment systems have yet to be studied.Based on this,this paper uses simulation method to take DOC+DPF+SCR+AOC system as the research object to study the coupling characteristics of diesel engine exhaust integrated aftertreatment system.According to the technical parameters of the existing diesel engine,diesel vehicle and integrated after-treatment system,the GT-Power simulation model of the working process of the diesel engine,the GT-Power simulation model of each sub-aftertreatment system and the integrated aftertreatment system,and the road cycle conditions of the diesel vehicle GT-Driver simulation model of the working process.Under different diesel engine operating conditions,the reaction characteristics of the integrated aftertreatment system were studied;Using the obtained diesel engine exhaust characteristic parameters,the effects of different exhaust parameters,catalyst structure parameters,chemical reaction parameters,and different layout schemes on the catalytic conversion characteristics of the integrated aftertreatment system were studied.Under the regeneration condition of DPF,the catalytic conversion effect of DOC+CDPF+SCR+AOC system on NOx is worse than that of DOC+SCR+CDPF+AOC system,but the catalytic conversion effect on CO is not as good as that of DOC+SCR+CDPF+AOC system.Based on the study of the dynamic emissions of diesel vehicles under road conditions,the simulation model of the working process of the diesel vehicle and the integrated aftertreatment system is coupled to study the transient response characteristics and influencing factors of the integrated aftertreatment system.Through the comparison of the reaction characteristics of each subsystem and other subsystems when they are coupled and when they work alone,the coupling effect between the subsystems of the integrated post-processing system is studied:The effect of coupling on the average pressure of DOC is obviously greater than the average temperature,and it has little effect on the conversion of CO,HC,and NO in DOC;it has little effect on DPF purification particles;for SCR,the efficiency of NO conversion during coupling is greater than that of NO₂ The conversion efficiency is less than when working alone;the NH₃ conversion rate of AOC during coupling work changes with time to be more stable.This paper makes a corresponding study on the effect of integrated aftertreatment system on diesel engine exhaust purification and the mutual coupling between the various aftertreatment systems.The research results can provide research for diesel engine exhaust aftertreatment technology and the development of integrated aftertreatment system Theoretical and technical basis.