Regulating particle number measurements from the tailpipe of light-duty vehicles: The next step?

Tailpipe emissions of a pool of 13 Euro 6b light-duty vehicles (eight diesel and five gasoline-powered) were measured over an extensive experimental campaign that included laboratory (chassis dynamometer), and on-road tests (using a portable emissions measurement system). The New European Driving Cycle (NEDC) and the Worldwide harmonised Light-duty vehicles Test Cycle (WLTC) were driven in the laboratory following standard and extended testing procedures (such as low temperatures, use of auxiliaries, modified speed trace). On-road tests were conducted in real traffic conditions, within and outside the boundary conditions of the regulated European Real-Driving Emissions (RDE) test. Nitrogen oxides (NOX), particle number (PN), carbon monoxide (CO), total hydrocarbons (HC), and carbon dioxide (CO2) emission factors were developed considering the whole cycles, their sub-cycles, and the first 300 s of each test to assess the cold start effect. Despite complying with the NEDC type approval NOX limit, diesel vehicles emitted, on average, over the WLTC and the RDE 2.1 and 6.7 times more than the standard limit, respectively. Diesel vehicles equipped with only a Lean NOX trap (LNT) averaged six and two times more emissions over the WLTC and the RDE, respectively, than diesel vehicles equipped with a selective catalytic reduction (SCR) catalyst. Gasoline vehicles with direct injection (GDI) emitted eight times more NOX than those with port fuel injection (PFI) on RDE tests. Large NOX emissions on the urban section were also recorded for GDIs (122 mg/km). Diesel particle filters were mounted on all diesel vehicles, resulting in low particle number emission (~1010 #/km) over all testing conditions including low temperature and high dynamicity. GDIs (~1012 #/km) and PFIs (~1011 #/km) had PN emissions that were, on average, two and one order of magnitude higher than for diesel vehicles, respectively, with significant contribution from the cold start. PFIs yielded high CO emission factors under high load operation reaching on average 2.2 g/km and 3.8 g/km on WLTC extra-high and RDE motorway, respectively. The average on-road CO2 emissions were ~33% and 41% higher than the declared CO2 emissions at type-approval for diesel and gasoline vehicles, respectively. The use of auxiliaries (AC and lights on) over the NEDC led to an increase of ~20% of CO2 emissions for both diesel and gasoline vehicles. Results for NOX, CO and CO2 were used to derive average on-road emission factors that are in good agreement with the emission factors proposed by the EMEP/EEA guidebook.

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Particle number (PN) emissions from gasoline, diesel, LPG, CNG and hybrid-electric light-duty vehicles under real-world driving conditions

Atmospheric Environment ◽

10.1016/j.atmosenv.2019.117126 ◽

2020 ◽

Vol 222 ◽

pp. 117126 ◽

Cited By ~ 10

Author(s):

A. Kontses ◽

G. Triantafyllopoulos ◽

L. Ntziachristos ◽

Z. Samaras

Keyword(s):

Real World ◽

Particle Number ◽

Light Duty ◽

Electric Light ◽

Hybrid Electric ◽

Driving Conditions ◽

Light Duty Vehicles

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Investigation of EURO-5/6 Level Particle Number Emissions of European Diesel Light Duty Vehicles

10.4271/2010-01-0789 ◽

2010 ◽

Cited By ~ 21

Author(s):

Ulf Kirchner ◽

Rainer Vogt ◽

Matti Maricq

Keyword(s):

Particle Number ◽

Light Duty ◽

Light Duty Vehicles

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Solid Particle Number (SPN) Portable Emissions Measurement Systems (PEMS) in the European Legislation: A Review

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16234819 ◽

2019 ◽

Vol 16 (23) ◽

pp. 4819 ◽

Cited By ~ 12

Author(s):

Barouch Giechaskiel ◽

Pierre Bonnel ◽

Adolfo Perujo ◽

Panagiota Dilara

Keyword(s):

Measurement Uncertainty ◽

Solid Particle ◽

Particle Number ◽

The United States ◽

Gaseous Pollutants ◽

Heavy Duty ◽

Measurement Systems ◽

Light Duty ◽

Evaluation Phase ◽

Light Duty Vehicles

Portable emissions measurement systems (PEMS) for gaseous pollutants were firstly introduced in the United States regulation to check the in-use compliance of heavy-duty engines, avoiding the high costs of removing the engine and testing it on a dynamometer in the laboratory. In Europe, the in-service conformity of heavy-duty engines has been checked with PEMS for gaseous pollutants since 2014. To strengthen emissions regulations with a view to minimise the differences between on-road and laboratory emission levels in some cases, PEMS testing, including solid particle number (SPN), was introduced for the type-approval of light-duty vehicles in Europe in 2017 and for in-service conformity in 2019. SPN-PEMS for heavy-duty engines will be introduced in 2021. This paper gives an overview of the studies for SPN-PEMS from early 2013 with the first prototypes until the latest testing and improvements in 2019. The first prototype diffusion charger (DC) based systems had high differences from the reference laboratory systems at the first light-duty vehicles campaign. Tightening of the technical requirements and improvements from the instrument manufacturers resulted in differences of around 50%. Similar differences were found in an inter-laboratory comparison exercise with the best performing DC- and CPC- (condensation particle counter) based system. The heavy-duty evaluation phase at a single lab and later at various European laboratories revealed higher differences due to the small size of the urea generated particles and their high charge at elevated temperatures. This issue, along with robustness at low ambient temperatures, was addressed by the instrument manufacturers bringing the measurement uncertainty to the 50% levels. This measurement uncertainty needs to be considered at the on-road emission results measured with PEMS.

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Road vehicles - Supplementary grip devices for tyres of passenger cars and light duty vehicles

10.3403/bsen16662 ◽

2020 ◽

Keyword(s):

Road Vehicles ◽

Passenger Cars ◽

Light Duty ◽

Light Duty Vehicles

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Monte Carlo Simulation Methodology to Assess the Impact of Ambient Wind on Emissions from a Light-Commercial Vehicle Running on the Worldwide-Harmonized Light-Duty Vehicles Test Cycle (WLTC)

Energies ◽

10.3390/en14030661 ◽

2021 ◽

Vol 14 (3) ◽

pp. 661

Author(s):

Alexandros T. Zachiotis ◽

Evangelos G. Giakoumis

Keyword(s):

Monte Carlo Simulation ◽

Energy Consumption ◽

Commercial Vehicle ◽

Ambient Wind ◽

Simulation Methodology ◽

Road Load ◽

Light Duty ◽

Light Commercial Vehicle ◽

Light Duty Vehicles ◽

The Impact

A Monte Carlo simulation methodology is suggested in order to assess the impact of ambient wind on a vehicle’s performance and emissions. A large number of random wind profiles is generated by implementing the Weibull and uniform statistical distributions for wind speed and direction, respectively. Wind speed data are drawn from eight cities across Europe. The vehicle considered is a diesel-powered, turbocharged, light-commercial vehicle and the baseline trip is the worldwide harmonized light-duty vehicles WLTC cycle. A detailed engine-mapping approach is used as the basis for the results, complemented with experimentally derived correction coefficients to account for engine transients. The properties of interest are (engine-out) NO and soot emissions, as well as fuel and energy consumption and CO2 emissions. Results from this study show that there is an aggregate increase in all properties, vis-à-vis the reference case (i.e., zero wind), if ambient wind is to be accounted for in road load calculation. Mean wind speeds for the different sites examined range from 14.6 km/h to 24.2 km/h. The average increase in the properties studied, across all sites, ranges from 0.22% up to 2.52% depending on the trip and the property (CO2, soot, NO, energy consumption) examined. Based on individual trip assessment, it was found that especially at high vehicle speeds where wind drag becomes the major road load force, CO2 emissions may increase by 28%, NO emissions by 22%, and soot emissions by 13% in the presence of strong headwinds. Moreover, it is demonstrated that the adverse effect of headwinds far exceeds the positive effect of tailwinds, thus explaining the overall increase in fuel/energy consumption as well as emissions, while also highlighting the shortcomings of the current certification procedure, which neglects ambient wind effects.

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