Combination of LNT and Passive SDPF – A System Assessment for Small Passenger Car Diesel Engines under RDE Conditions

Authors

DI Reinhard Ratzberger, Dr. Eberhard Schutting, Univ.-Prof. Dr. Helmut Eichlseder,
Institute of Internal Combustion Engines and Thermodynamics,
University of Technology Graz;
Dr. Klaus Hadl, DI Martin Wieser, DI (FH) Horst Mitterecker,
AVL List GmbH, Graz

Summary

The market share of Diesel engines for small passenger cars in Europe and India will be strongly dependent on the complexity of future Exhaust Aftertreatment Systems (EAS). A Lean-NO_X-Trap (LNT) in combination with a conventional Diesel Particulate Filter (DPF) was extensively applied for Euro 6b. With regard to Real Driving Emissions (RDE) legislation, high load engine operation and component aging, LNTs reach their boundaries of an efficient NO_X conversion. Thus, measures are required to support the NO_X conversion beyond the restricted operating range of the LNT. Therefore, a system was tested which additionally uses Selective Catalytic Reduction (SCR) yet without active AdBlue^® dosing, i.e. passive SCR. The LNT was combined with a DPF extended with an SCR coating (SDPF) in a close-coupled arrangement. A major focus of the investigation was on the operation during aggressive driving cycles, in order to counteract the especially here distinct restrictions of a hot-end LNT by the addition of the SDPF. Depending on the vehicle, it can accordingly be dispensed with an active AdBlue^® dosage in wide operating areas.

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