OPEN ACCESS
Real-world testing of a set of modern vehicles show that most petrols meet their Euro standards fornitrous oxides (NOx), while most diesel vehicles exceed them. However, that some diesel vehicles met their Euro standards implies exceedances are not peculiar to the fuel. Likewise, the compliance of the tested petrol vehicles with the standard does not mean all petrol vehicles do. Engine maps were synthesized which reproduced trip level emissions to within 10% of that gathered under real-world driving conditions. Average velocity alone, such as what is used in COPERT, is a poor predictor of emissions. Stepwise linear models showed NOx emissions could be predicted accurately by incorporating other metrics, such as maximum deceleration and the variance of velocity over the driving cycle. The models were validated on three driving cycles where all vehicles met their Euro standards, save Euro 6 diesel vehicles on the US highway cycle. COPERT overestimated NOx from all vehicles. More work is required to combine driving cycle metrics with vehicle characteristics, such as mass and peak engine torque, to identify the conditions under which vehicles exceed their Euro limits.
COPERT, diesel vehicles, engine maps, Euro standards, NOx emissions, PEMS, vehicle simulation, urban emissions
[1] EEA , Air quality in Europe – 2015 report. European Environment Agency, 2015.
[2] Franco, V., Sànchez, F.P., German, J. & Mock, P., Real-world exhaust emissions from modern diesel cars: A meta-analysis of PEMS emissions data from EU (Euro 6) and US (Tier 2 Bin 5/ULEV II) diesel passenger cars – Part 1: Aggregated results. White paper, The International Council on Clean Transportation, Berlin, 2014.
[3] Rexeis, M. et al., Update of Emission Factors for EURO 5 and EURO 6 vehicles for the HBEFA Version 3.2, Graz University of Technology: Graz, chapter Exhaust emissions from road transport, 2013.
[4] USEPA, Development of emission rates for light-duty vehicles in the motor vehicles emissions simulator (moves 2010). Technical Report EPA-420-R-11- 011, Environmental Protection Agency, Washington DC, 2011.
[5] EC, Type approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information. European Parliament and the Council, 2007.
[6] Bishop, J.D.K., Stettler, M.S., Molden, N. & Boies, A.M., Engine maps of fuel use and emissions from transient driving cycles. Applied Energy, 2016.
[7] Mackovjak, J.M., Light Duty Vehicle NOx Emission Factor Modelling Utilizing Speed and Vehicle Specific Power Measured from a Portable Emission Measuring System. Master’s thesis, University of Cambridge, 2015.