| With the strict emission regulations,new requirements are put forward for aftertreatment system.As an indispensable part of the diesel engine,the diesel engine aftertreatment system can effectively reduce pollutants exported by the diesel engine.But in the development process,the calibration of aftertreatment system often costs a lot of resources.Numerical simulation can effectively reduce the cost of resources in the process of bench calibration,improve efficiency and reduce development cycle.The experiment can truly reflect the performance of catalyst,which is of great significance to the evaluation and research of catalyst performance.In this paper,numerical simulation and small-scale catalyst’s experiment are combined to improve the calibration accuracy of the aftertreatment system and shorten the development cycle.The conditions of experiment are set up based on the conditions of bench test,which is more consistent with the actual use of catalyst.The influence of water vapor on the storage performance of NH3 was investigated by experiment,and the oxidation performance of NH3,NO,standard SCR,fast SCR and NO2-SCR of Cu-based zeolite catalyst were also tested.Furthermore,the effects of different NO2/NOx ratio on NOx conversion,N2 O production and transient response of Cu zeolite catalyst were also studied through sample tests.A one-dimensional reaction kinetics model was established based on BOOST,and the model was validated with sample test data.The formation of NH4NO3 at low temperature would inhibit the occurrence of SCR reaction,so the formation mechanism of NH4NO3 at low temperature should be considered.The hot WHTC test was carried out by inputting the verified reaction kinetic parameters.Since the amount of urea injection was adjusted by calculating the coverage of NH3 on the catalyst surface,the accuracy of the model would seriously affect the specific emission results.The experimental results showed that the reaction kinetics model verified by steady-state test data would be inhibited by NH4NO3 at low temperature,resulting in the model underestimating the catalytic activity of the catalyst at low temperature.After modifying the NH4NO3 inhibition effect at low temperature by optimizing the kinetic parameters,the accuracy of the model at low temperature was improved and the specific emission of NOx was reduced. |
