| NOX emissions of diesel engine combustion is one of the main atmospheric pollutants,Selective catalytic reduction(SCR)technology is one of the effective methods to reduce nitrogen oxide emissions.In order to meet the emission control regulations which is increasingly strict day by day? It is particularly important to design and optimize the SCR system,the simulation calculation of urea aqueous solution injection process can help the designer understand the physical phenomena that occurred in front of the catalytic converter,able to optimize design,as well as make SCR system develop and design more efficient.This paper is aimed at fluid simulation afertreatment system(DOC+SCR)of un-road ?-stage engine,introduces the simulation analysis method of the urea injection process and the evaporation process simulation analysis method.The velocity uniformity and NH3 uniformity distribution coefficient of DOC and SCR cross-section,the system pressure drop and liquid membrane accumulation to determine whether a post-processing system reaches the requirement.At first,simulate the original geometric model under four operating conditions,but not able meet the requirement.Then adjust urea injection location,mixer installation and the shape of mixer,at last meet engineering application of afertreatment system,the analysis is shown as below:1.velocity distribution uniformity of inlet cross-section of DOC.2.The velocity and NH3 distribution uniformity before catalytic converter is analyzed.3.Research the formation and development of the liquid membrane(urea aqueous solution)on the wall,including the location of the liquid film appeared,thickness, and wall heat transfer process and the evaporation process.4.In order to predict and reduce the crystallization,simulate and research the wall temperature distribution of the SCR system.5.pressure drop distribution of the afertreatment system. |
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