Study on Correlation between After-Treatment Performance and Running Conditions, Exhaust Parameters of Heavy-Duty Diesel Vehicle 2018-01-0338

The increasingly stringent emission regulations have mandated the use of CCRT (catalyzed continuously regeneration trap) made by upstream DOC (diesel oxidation catalyst) and downstream CDPF (catalyzed diesel particulate filter) for heavy-duty diesel vehicles, which is proved to be the only way that can efficiently control the gaseous and particulate emissions. The performance of after-treatment is greatly influenced by the running conditions of the diesel vehicle and its exhaust parameters, so this paper intended to use grey relational analysis to study the correlation between running conditions (velocity, acceleration, VSP (vehicle specific power)), exhaust parameters (exhaust flow rate, DOC inlet temperature, concentrations of CO, THC, O₂ and NO_X) and the performance of DOC and CCRT based on chassis dynamometer test. Results showed that the effect of DOC on CO and THC is mainly affected by exhaust flow rate, exhaust temperature and THC concentration. This also applied to effect on CCRT on CO. But for the effect of CCRT on THC, the most important three factors are exhaust temperature, O₂ and THC concentration. The trapping effect of DOC on PN (particle number) was greatly affected by vehicle speed, exhaust flow rate and exhaust temperature, while for CCRT, the trapping effect on both PN and PM (particle mass) are greatly affected by exhaust temperature, THC and O₂ concentration. And the exhaust flow rate is also a noticeable factor for the effect of CCRT on PM. In terms of the pressure drop of CCRT, the important factors are ranked as: THC concentration > exhaust flow rate > PN reduction = PM reduction. In summary, the performance of DOC and CCRT was greatly affected by the exhaust flow and temperature, while the THC concentration of the engine was also a main factor.