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The gap between diesel vehicle emissions in laboratory tests compared to those in use has been addressed by the introduction of the Real Driving Emissions (RDE) requirements. Modern diesel technology now demonstrates low emissions on the road over a wide range of driving conditions. This paper further demonstrates that consistent low nitrogen oxide (NOx) and particle number (PN) emissions can be achieved over a wide range of driving conditions beyond Euro 6d RDE requirements, with emission control technologies combined in an integrated approach. An LNT (Lean NOx Trap) is combined with a dual-dosing SCR (Selective Catalytic Reduction) system. Low-load NOx control is achieved by the LNT in combination with a close-coupled SCR coated on the Diesel Particulate Filter (SDPF). High load conditions, on the other hand, are covered by the underfloor SCR system with a second AdBlue® injector.

The market share of Gasoline Direct Injection (GDI) vehicles has been increasing, promoted by its positive contribution to the overall fleet fuel economy improvement. It has however been reported that this type of engine is emitting more ultrafine particles than the Euro 6c Particle Number (PN) limit of 6·1011 particles/km that will be introduced in Europe as of September 2017 in parallel with the Real Driving Emission (RDE) procedure. The emissions performance of a Euro 6b GDI passenger car was measured, first in the OEM build without a Gasoline Particulate Filter (GPF) and then as a demonstrator with a coated GPF in the underfloor position. Regulated emissions were measured on the European regulatory test cycles NEDC and WLTC and in real-world conditions with Portable Emissions Measurement Systems (PEMS) according to the published European RDE procedure (Commission Regulation (EU) 2016/427 and 2016/646).

The exhaust emissions of two Euro 6 diesel cars with different emissions control systems have been evaluated both on the road and over various chassis dynamometer test cycles. European emissions limits are currently set using the New European Driving Cycle (NEDC), but the European Commission is preparing additional test procedures to ensure that emissions are well controlled both in real-world use and over the legislative test cycle. The main focus of this work on ‘Real Driving Emissions’ (RDE) is on measurements using Portable Emissions Measurement Systems (PEMS) in truly representative, on-road, driving. A key focus of the test programme, undertaken as a collaboration between AECC (the Association for Emissions Control by Catalyst) and Ricardo UK, was therefore the use of PEMS systems to measure on-road emissions of both gaseous pollutants and particulate matter. This included measurement of particle number emissions with a new candidate system for this type of measurement.

From 1 September 2014 new car types in the EU must meet ‘Euro 6’ emissions requirements. The ‘New European Driving Cycle’ (NEDC) is currently the main test for this, but the European Commission intends to also introduce PEMS (Portable Emissions Measurement Systems)-based procedures to ensure that emissions are well controlled in real use. ‘Random Cycles’ have also been considered and remain a possible option for ‘real world’ particle number measurement. At the same time, the UN Working Party on Pollution and Energy (GRPE) has developed the new Worldwide harmonized Light vehicles Test Procedure (WLTP) that is expected to be adopted in the EU in the near future. To identify and understand the differences in emissions that may arise between these various methodologies, AECC has conducted some initial tests on two modern light-duty vehicles.

AECC, the Association for Emissions Control by Catalyst, conducted a test program to compare the newly developed World-harmonized Light vehicles Test Cycle (WLTC) with the current European regulatory New European Drive Cycle (NEDC) and the cold-start Common Artemis Driving Cycle (CADC). Vehicle engines and aftertreatment technologies were selected to cover a wide range of future systems. Six European commercially available passenger cars were chosen: three Euro 5 Gasoline Direct Injection cars, two Euro 6 Diesel cars and a Euro 5 non-plug-in gasoline hybrid car. The hybrid car was tested with three different battery state of charge: nominal, minimum charge, and maximum charge. Investigations on the test temperature were also conducted by comparing emissions at 25°C and at −7°C. Regulated gaseous emissions (HC, CO, NOx) and particulate mass and particles number were measured, together with additional pollutants such as CH4, NO2 and ammonia.

Four state-of-the-art >500 cc Euro 3 and one 150 cc Indian specification motorcycles were selected and evaluated over the Euro 3 and world harmonized WMTC test cycles for regulated pollutants and particles. The objectives of the work were to examine the correlation between emissions on the WMTC and Euro 3 cycles, to compare those results with previous work completed before the European WMTC limits were set, to examine particulate emissions, and to then evaluate the durability of one machine. The correlation between Euro 3 and WMTC emissions results was used to extrapolate the appropriate level of WMTC limit values from the emissions limits on the Euro 3 test cycle. These WMTC extrapolated emissions limits were in line with the previous AECC motorcycle test program conducted in 2004 on Euro 2 motorcycles and also confirmed the appropriate level of the WMTC Euro 3 limits set in European Directive 2006/72/EC amending 97/24/EC.

The paper is aimed at investigating backpressure and backpressure variation of three way catalysts (TWC). Results presented show that backpressure variation is influenced by measurement error, substrate dimensional variation, and washcoat thickness. A broad range of anticipated washcoat differences between coaters is also considered. Results provided shows that Delphi high-flow FlexMetal catalyst achieves optimum emissions control with up to 40% less backpressure, leading to 5% additional torque on a 3.2 L engine.

Euro IV emissions limits have become a major milestone for the car industry in Europe. To comply with reduced emissions targets, a significant effort was required to minimize light-off time and to improve steady state performance for the pollutants HC and NOx. The main challenges and the technical solutions are discussed in this present work. Among them are substantial catalyst improvements needed to accommodate the progressively more severe agings related to high-speed driving conditions in Europe, and the close-coupled location of the catalyst, with the introduction of the converter welded directly to the exhaust manifold. Vehicles equipped with Euro IV emissions systems have been running in the field for more than 2 years and have shown that only a systems approach, including optimized exhaust manifold and canning designs, robust engine calibration strategies and specifically developed washcoats, can lead to a cost effective emissions solution.