Experimental assessment addressing EU Real-Driving Emission (RDE)
Passenger cars are an important source of air pollution, especially in urban areas. Recently, real-driving emissions (RDE) test procedures have been introduced in the EU aiming to evaluate nitrogen oxides (NOx) and particulate number (PN) emissions from passenger cars during on-road operation. Although RDE accounts for a large variety of real-world driving, it excludes certain driving situations by setting boundary conditions (e.g., in relation to altitude, temperature or dynamic driving).
The present work investigates the on-road emissions of NOx, NO2, CO, particle number (PN) and CO2 from a fleet of nineteen Euro 6b, 6c and 6d-TEMP vehicles, including diesel, gasoline (GDI and PFI) and compressed natural gas (CNG) vehicles. The vehicles were tested under different on-road driving conditions outside boundaries. These included ‘baseline’ tests, but also testing conditions beyond the RDE boundary conditions to investigate the performance of the emissions control devices in demanding situations.
Consistently, low average emission rates of PN and CO were measured from all diesel vehicles tested under most conditions. Moreover, the tested Euro 6d-TEMP and Euro 6c diesel vehicles met the NOx emission limits applicable to Euro 6d-TEMP diesel vehicles during RDE tests (168 mg/km). The Euro 6b GDI vehicle equipped with a gasoline particulate filter (GPF) presented PN emissions < 6×1011 #/km. These results, in contrast with previous on-road measurements from earlier Euro 6 vehicles, indicate more efficient emission control technologies are currently being used in diesel and gasoline vehicles.
However, the results described in this report also raise some new concerns. In particular, the emissions of CO (measured during the regulated RDE test, but without an emission limit associated to it) or PN from PFI vehicles (presently not covered by the Euro 6 standard) showed elevated results in some occasions. Emissions of CO were up to 7.5 times higher when the more dynamic tests were conducted and the highest PN emissions were measured from a PFI gasoline vehicle during dynamic driving.
The work also investigates how NOx, CO, PN and CO2 on-road emissions from three vehicles are impacted by sub-zero ambient temperatures and high altitudes. Two of the tested vehicles were Euro 6d-TEMP certified vehicles, one diesel and one gasoline, and one was a Euro 6b plug-in hybrid vehicle. The vehicles were studied during tests that do not fulfil the boundary conditions in terms of maximum altitude, altitude gain, and/or minimum temperature. The obtained emissions were compared to those obtained during tests performed along RDE routes.
The results indicate that cold ambient temperature and high altitude, outside the RDE boundary conditions, lead to in higher NOx, CO and PN emissions compared to moderate conditions of temperature and altitude. Nonetheless, the two Euro 6d-TEMP vehicles tested in those extreme conditions yielded NOx emissions factors that fulfilled the Euro 6d-TEMP emission requirements.
Our work underlines the importance of a technology- and fuel-neutral approach to vehicle emission standards, whereby all vehicles must comply with the same emission limits for all pollutants.
SUAREZ BERTOA Ricardo;
ASTORGA-LLORENS Maria;
FRANCO Vicente;
KREGAR Zlatko;
VALVERDE MORALES Victor;
CLAIROTTE Michael;
PAVLOVIC Jelica;
GIECHASKIEL Barouch;
2019-10-30
Publications Office of the European Union
JRC115979
978-92-76-14123-5 (online),
978-92-76-14124-2 (print),
978-92-76-14150-1,
1831-9424 (online),
1018-5593 (print),
EUR 29905 EN,
OP KJ-1A-29905-EN-N (online),
OP KJ-1A-29905-EN-C (print),
OP KJ-1A-29905-EN-E,
https://publications.jrc.ec.europa.eu/repository/handle/JRC115979,
10.2760/003337 (online),
10.2760/214318 (print),
10.2760/722722,
