The Design And Research Of Emission Aftertreatment Device For The Regulation Of The Stage ? Of The Non-road Diesel Engine In China

Due to its high thermal efficiency,low fuel consumption,high output power and low emissions,diesel engines play an important role in agricultural production and urban development,but the emission problems are becoming more and more serious.The developed countries such as the United States,the European Union,and Japan have realized the importance of controlling emissions from the non-road diesel engines.A series of emission regulations have been enacted.And a largr number of studies have been conducted on their emission control technologies.And as a result,the emission levels of the non-road diesel engines have been greatly improved.China began to enact the emission regulations and do some research of non-road diesel engines very late.And in China,non-road diesel engines have large reserves with poor emission levels.China is in the stage of transition from China III to China IV currently.Therefore,it is of great significance to study the control technology for the non-road IV emission regulation.In this paper,the influence of DPF structure parameters on trapping performance and pressure drop is studied.And the influence of DOC structure parameters on pollutant conversion efficiency is researched.The DPF regeneration method is designed.It also research the influencing factors of PM combustion in DPF.Firstly,analyze the development and status quo of non-road diesel engine emission regulations in the United States,the European Union and China.And in this paper,it introduces the purification measure of diesel engine and aftertreatment technology to reduce NO_X and PM.Based on a diesel engine of China?emission,according the emission test results,in order to achieve the China?emission standard,put forward and analyze two emission technology routes,and finally adopt the route of EGR+DOC+DPF.Secondly,begin to do the research and design of the aftertreatment device.A simulation model of DPF performance is established.The calibration conditions of the2200r/min full-load of the diesel engine is studied.And research the variation law of DPF capture performance and pressure drop with filter length,CPSI,porosity,micropore diameter and filter wall thickness.The DOC performance simulation model is established.And research the effects of CPSI and carrier length on CO,HC and NO conversion.According to the research results,the exhaust aftertreatment device is designed and loaded into the engine for steady and transient conditions to do the emission test.As a result,the test shows that the pollutants meet the non-road IV standard of China.Finally,a regeneration study of DPF is performed.Based on the passive continuous regeneration technology,in order to improve the NO conversion of DOC,research the effects of exhaust gas temperature,exhaust gas mass flow rate and exhaust oxygen concentration on the NO conversion.The result shows that the secondary gas can increase the NO conversion,and promote passive continuous regeneration.According to the DPF fuel-injection catalytic combustion regeneration method,the fuel-assisted combustion catalytic regeneration bench test is designed.The regeneration model is built based on GT Power.By optimizing the injection timing,fuel and oxygen injection rate,the heating time shortens 140s and the maximum temperature increases10°C.The simulation model of PM combustion in DPF is established.And the effects of initial soot mass,exhaust oxygen concentration and particle activation energy on PM combustion are analyzed.It indicates that the DPF regenerative back-pressure should be properly set to avoid the filter temperature being too high.The appropriate oxygen replenishment should be carried out to shorten the time for the combustion of the PM.It also indicates that the lower the activation energy of the PM,the shorter the regeneration time.