Assessment of Light Duty Diesel After-Treatment Technology Targeting Beyond Euro 6d Emissions Levels

Since previous publications, Ricardo have continued to investigate the development of advanced after-treatment technologies through model based system simulation using an integrated model based development (IMBD) approach. This paper presents the results of the evaluation of after-treatment systems and management strategies for a range of diesel passenger cars. The targets of this study are applicable to Real Driving Emissions (RDE) legislation, but now targeting emissions levels beyond Euro 6d. The work was carried out as part of the EC Horizon 2020 co-funded REWARD (Real World Advanced technologies foR Diesel engines) project. Owing to the wide variation in feed-gas properties expected over an RDE cycle, the results seen for current production system architectures such as Lean NO_X traps (LNT) or actively dosed Selective Catalytic Reduction (aSCR) systems highlight the challenge to adhere to emissions limitations for RDE legislation whilst fulfilling stringent CO₂ targets. Optimisation of both the after-treatment system configuration and control strategies are required. Vehicle simulation has been performed with a range of after-treatment system specifications and engine-out feed-gas properties. The work includes an assessment of exhaust thermal management with regards to catalyst performance. The results are evaluated considering a range of criteria including; emissions control capability, estimated system on-cost, packaging limitations, fuel consumption penalty and additional fluid consumption. After-treatment system recommendations are made that deliver appropriate emissions control for a range of legislative, RDE and urban cycles for a selection of light duty diesel applications.