Ultra-Low Heavy-Duty Diesel NOx Emissions in Real World Conditions
12524
Abstract
The Euro VI Step E emission standard for heavy-duty vehicles (HDVs) is the first to introduce limits for solid particle number (PN) to be measured with Portable Emissions Measurement Systems (PEMS) under In-Service conformity (ISC). In addition, Cold Start emissions during on-road operation are now included. The measured emissions resulting from the on-road testing are analyzed through the Moving Average Window (MAW) evaluation procedure as prescribed in the EU regulation, where data boundary conditions are also applied, leaving non-negligible emissions data unaccounted for in the determination of the final result. The preparatory work for the definition of the European Commission proposal for a Heavy-duty Euro VII emissions regulation is ongoing, and the discussion on vehicle compliance is shifting from structured ISC on-road test trips to Real World operation. This shift emphasizes the need to reduce pollutant emissions in a wide regime of operating conditions in order to minimize individual exposure to pollutants. The objective of the work presented is to show ultra-low diesel NOx and particulate emissions capability across a wide range of real-world operating conditions on a heavy-duty vehicle, and more specifically, address emissions reduction at low average speeds and loads in urban operation. To achieve this objective, a system combining state-of-the-art emission control technologies containing Diesel Oxidation Catalyst (DOC), Selective Catalytic Reduction (SCR), catalized Diesel Particulate Filter (cDPF) and Ammonia Oxidation Catalyst was implemented on a diesel N3 long haul tractor. Two SCR volumes are included, one close-coupled and one underfloor, with dual NH3 dosing. On-road testing was conducted to evaluate the system performance for regulated (NOx, PN, CO, THC) and non-regulated pollutants (NH3, N2O and CH4). Results will be presented.