Performance Estimation Of Diesel After-treatment Device In Service Process Based On Data-driven

In China,emissions from some diesel vehicles is seriously exceeded the requirements of laws and regulations,the forced elimination of such vehicles will result in a great economic burden.Therefore,the government took the lead in many cities to carry out retrofitting of after-treatment devices for in-use diesel vehicles.The DOC+CDPF’s technical route has effectively reduced the emissions of such vehicles.The after-treatment device may be damaged or blocked during its service,which may have a great impact on the vehicle performance.Therefore,the performance of the after-treatment device needs to be monitored.This thesis take the CRT as the research object,which is coupled with DOF and CDPF.Its performance influencing factors and influence laws have been studied,and performance estimation methods for the faults that occur during the service process have been proposed.Based on the detailed analysis of the physical and chemical processes during DOC and CDPF working,the theoretical models of temperature field and pressure drop for DOC and CDPF were established.According to the structural parameters of the aftertreatment device,a one-dimensional simulation model was established based on GTPower.The performance of the model was verified by bench test and vehicle data.The influence laws of exhaust gas composition,exhaust mass flow,and exhaust temperature on the post-treatment devices under steady-state conditions were studied.Under transient conditions,the influence laws of abrupt changes in exhaust temperatures,mass flow,and different carbon loads on the temperature transfer phenomenon of the after-treatment device were studied.Under the road conditions,the simulation of the blockage and damage of the aftertreatment device was performed.Based on the influence of failure modes on the aftertreatment device temperature,a performance estimation method based on the accumulated value of the temperature difference and and a performance estimation method based on the temperature-related were proposed.Methods use statistical means to eliminate the effects of high-frequency changes in road conditions during normal driving condition.A remote monitoring system for emission control after-treatment device was developed.More than 1,800 in-use vehicles’ after-treatment device data had been collected,and the problems existing in the original data have been pre-processed.Taking two typical vehicles as examples,the temperature data of the after-treatment device are analyzed.The research shows that: in the amplitude domain,distribution of the three measuring points temperature of the normal status after-treatment device is relatively concentrated,and the probability density distribution of temperature difference presents similarity with normal distribution with 0 as the mean;blocking of the after-treatment device would cause the outlet temperature to deviate from the temperature of other measuring points,and the temperature difference is mostly distributed in positive values.In the time difference domain,the delay time of the normal status after-treatment device is stable within 30~40s;and the delay time of the blocking after-treatment device is increased from 42 s to 76 s.It also validated the effectiveness of the performance estimation methods.In this thesis,the performance influencing factors and laws of after-treatment devices have been studied,and methods for estimating the performance of aftertreatment devices witch suitable for in-use vehicles have been proposed.The results has a certain value on the in-use vehicle retrofit device reconstruction project and the after-treatment device remote performance monitoring.