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Human health and the environment are heavily impacted by air pollution. Air quality standards for Nitrogen dioxide (NO2) and particulate matter (PM) are commonly exceeded in Europe, particularly in urban areas with high density of traffic. Road transport contributed to 39% of NOx emissions, and 11% of PM emissions in the European Union (EU) in 2017. Measurements with Portable Emissions Measurement Systems (PEMS) showed that most Euro 5 and Euro 6b diesel vehicles emitted significantly more NOx on the road than their permissible limit in the laboratory type-approval test. In that context, EU Real Driving Emissions (EU-RDE) regulation aims at securing low on-road emissions of light duty vehicles under normal conditions of use. This paper assesses the tailpipe emissions performance of Euro 6d-TEMP gasoline and diesel passenger cars, type-approved after the entry into force of the RDE regulation in September 2017.

Particle number (PN) emission limits were introduced in the European Union’s regulations for light-duty and heavy duty vehicles in the years 2011-2014. Since then, PN measurements have become a common practice in the automotive sector. Many studies showed that the current methodology, which counts particles >23 nm, misses a large fraction of particles for some engine technologies, such as port fuel injection vehicles or vehicles fueled with compressed natural gas (CNG). However, data for the latest technology vehicles are lacking. For this reason, we measured PN emissions >23 nm and >10 nm of >30 CNG, gasoline and diesel-fueled vehicles. Two systems were measuring in parallel from the full dilution tunnel; one with an evaporation tube and the other with a catalytic stripper. The PN emission levels spanned over three orders of magnitude depending on whether there was a particulate filter installed or not.

Recently, a particle number (PN) limit was introduced in the European light-duty vehicles legislation. The legislation requires measurement of PN, and particulate mass (PM), from the full dilution tunnel with constant volume sampling (CVS). Furthermore, PN measurements will be introduced in the next stage of the European Heavy-Duty regulation. Heavy-duty engine certification can be done either from the CVS or from a partial flow dilution system (PFDS). For research and development purposes, though, measurements are often conducted from the raw exhaust, thereby avoiding the high installation costs of CVS and PFDS. Although for legislative measurements requirements exist regarding sampling and transport of the aerosol sample, such requirements do not necessarily apply for raw exhaust measurements. Thus, measurement differences are often observed depending on where in the experimental set up sampling occurs.

By early 2007, all major manufacturers of light-duty diesel vehicles are marketing models equipped with diesel particulate filters (DPFs). However, there is still a lack of understanding of the particles emitted when the DPF undergoes regeneration. This paper focuses on measuring particle emissions of a representative light-duty diesel vehicle equipped with DPF and employing a fuel-borne catalyst (FBC) to aid regeneration. Particulate Matter (PM) and non-volatile particle number emissions are measured throughout testing according to the Particle Measurement Programme (PMP) proposals. In addition, an Engine Exhaust Particle Sizer (EEPS) connected directly to the CVS is used to give real time size distributions of both volatile and non-volatile particles. The paper focuses on particle emissions during regenerating New European Driving Cycles (NEDCs).

The regulation of particle number (PN) has been introduced in the Euro 5/6 light-duty vehicle legislation, as a result of the light duty inter-laboratory exercise of the Particle Measurement Program (PMP). The heavy-duty inter-laboratory exercise investigates whether the same or a similar procedure can be applied to the heavy-duty regulation. In the heavy-duty exercise two "golden" PN systems sample simultaneously; the first from the full dilution tunnel and the second from the partial flow system. One of the targets of the exercise is to compare the PN results from the two systems. In this study we follow a different approach: We use a PMP compliant system at different positions (full flow, partial flow and tailpipe) and we compare its emissions with a "reference" system always sampling from the full flow dilution tunnel.

The measurement of the particle number (PN) concentration of non-volatile particles ≻23 nm was introduced in the light-duty vehicles regulation; the heavy-duty regulation followed. Based on the findings of the Particle Measurement Program (PMP), heavy-duty inter-laboratory exercise, the PN concentration measurement can be conducted either from the full dilution tunnel with constant volume sampling (CVS) or from the partial flow dilution system (PFDS). However, there are no other studies that investigate whether the PN results from the two systems are equivalent. In addition, even the PMP study never investigated the uncertainty that is introduced at the final result from the extraction of a flow by a PN system from the PFDS. In this work we investigate the uncertainty for the three possible cases, i.e., considering a constant extracted flow from the PFDS, sending a signal with 1 Hz frequency to the PFDS, or feeding back the extracted flow to the PFDS.

Different particulate mass (PM) portable emission measurement systems (PEMS) were evaluated in the lab with three heavy-duty diesel engines which cover a wide range of particle emission levels. For the two engines without Diesel Particulate Filters (DPF) the proportional partial flow dilution systems SPC-472, OBS-TRPM, and micro-PSS measured 15% lower PM than the full dilution tunnel (CVS). The micro soot sensor (MSS), which measures soot in real time, measured 35% lower. For the DPF-equipped engine, where the emissions were in the order of 2 mg/kWh, the systems had differences from the CVS higher than 50%. For on-board testing a real-time sensor is necessary to convert the gravimetric (filter)-based PM to second-by-second mass emissions. The detection limit of the sensor, the particle property it measures (e.g., number, surface area or mass, volatiles or non-volatiles) and its calibration affect the estimated real-time mass emissions.

A proposal for sub-23 nm Solid Particle Number (SPN) measurement method was developed by the Particle Measurement Programme (PMP) group, based on the current SPN measurement method. In the proposal, a Particle Number Counter (PNC) having (65 ± 15)% counting efficiency at 10 nm and >90% at 15 nm (PNC10) replaces the current regulation PNC efficiency of 50±12% at 23 nm and >90% at 41 nm. Additionally, a catalytically active evaporation tube (CS) is required for sub-23 nm measurement method instead of the non-reactive evaporation tube (ET) of the current regulation. Here experimental work carried out at the JRC to address the issues of sub-23 nm SPN-measurement method is presented. The PNC10 was shown to be less dependent on the particle material than the PNC23, thus soot-like particles are still allowed for PNC-calibration. The high charging probability of soot-like particles was shown to have a low effect on PNC calibration uncertainties.