Experimental Assessment of NOx Emissions from 73 Euro 6 Diesel Passenger Cars

Controlling nitrogen oxides (NOx) emissions from diesel passenger cars during real-world driving is one of the major technical challenges facing diesel auto manufacturers. Three main technologies are available for this purpose: exhaust gas recirculation (EGR), lean-burn NOx traps (LNT), and selectiv...

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Bibliographic Details
Published in:Environmental science & technology 2015-12, Vol.49 (24), p.14409-14415
Main Authors: Yang, Liuhanzi, Franco, Vicente, Mock, Peter, Kolke, Reinhard, Zhang, Shaojun, Wu, Ye, German, John
Format: Article
Language:English
Subjects:
Air Pollutants - analysis
Automobile Driving - legislation & jurisprudence
Automobiles
Diesel fuels
Emission standards
Emissions control
Environmental science
Gasoline
Nitrogen
Nitrogen Oxides - analysis
Vehicle Emissions - analysis
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Summary:Controlling nitrogen oxides (NOx) emissions from diesel passenger cars during real-world driving is one of the major technical challenges facing diesel auto manufacturers. Three main technologies are available for this purpose: exhaust gas recirculation (EGR), lean-burn NOx traps (LNT), and selective catalytic reduction (SCR). Seventy-three Euro 6 diesel passenger cars (8 EGR only, 40 LNT, and 25 SCR) were tested on a chassis dynamometer over both the European type-approval cycle (NEDC, cold engine start) and the more realistic Worldwide harmonized light-duty test cycle (WLTC version 2.0, hot start) between 2012 and 2015. Most vehicles met the legislative limit of 0.08 g/km of NOx over NEDC (average emission factors by technology: EGR-only 0.07 g/km, LNT 0.04 g/km, and SCR 0.05 g/km), but the average emission factors rose dramatically over WLTC (EGR-only 0.17 g/km, LNT 0.21 g/km, and SCR 0.13 g/km). Five LNT-equipped vehicles exhibited very poor performance over the WLTC, emitting 7-15 times the regulated limit. These results illustrate how diesel NOx emissions are not properly controlled under the current, NEDC-based homologation framework. The upcoming real-driving emissions (RDE) regulation, which mandates an additional on-road emissions test for EU type approvals, could be a step in the right direction to address this problem.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.5b04242