Super Ultra-Low NOx Emissions under Extended RDE Conditions – Evaluation of Light-Off Strategies of Advanced Diesel Exhaust Aftertreatment Systems 2019-01-0742

Super ultra-low NOX emission engine concepts are essential to comply with future emission legislations. To meet the future emission standards, application of advanced diesel exhaust aftertreatment systems (EATS), such as Diesel Oxidation Catalyst (DOC), Lean NOX Trap (LNT), Selective Catalytic Reduction coatings on Soot Filters (SCRF) and underfloor SCR, is required. Effective customized thermal management strategies are essential to ensure fast light off of the ETAS after engine cold start, and to avoid significant cooldown during part load operation. This paper describes the investigation of different exhaust gas heating measures, such as intake throttling, late fuel injection, exhaust throttling, advanced exhaust cam phasing, retarded intake cam phasing, cylinder deactivation, full turbine bypass, electric catalyst heating and electrically heated intake manifold strategies. For these investigations, a steady-state GT-Power simulation model of a state-of-the-art EU6c 2.0L diesel engine, equipped with high and low pressure exhaust gas recirculation (EGR) and 2-stage boosting, was used. The results were then transferred to FEV´s complete powertrain simulation platform. As representative vehicles, a segment C car, a compact SUV and a light duty van have been selected, and have been investigated using the Worldwide Harmonized Light Vehicle Test Procedure (WLTP) and extended Real Driving Emissions (RDE) cycles. The results for the different vehicles together with all EATS configurations and their heating strategies are being compared and evaluated to demonstrate the potential in terms of a fast light off to guarantee optimal EATS operation conditions. At low engine loads RDE cycles, this potential amounts to a reduction of NOX tailpipe emissions of up to approximately 70 % and a benefit in CO2 emissions of approximately 3 % for example a light duty van.