1,721,139 research outputs found
Differences between tailpipe and dilution tunnel sub-23 nm non-volatile (solid) particle number measurements
No full textEuropean Union vehicle and engine regulations require measurement of non-volatile (solid) particles with diameter >23 nm at the dilution tunnel. In 2019 it was decided to include particles >10 nm in the post Euro 6/VI regulations. Recent studies showed that sub-23 nm measurements are not only susceptible to volatile artifacts (i.e. re-nucleation downstream of the evaporation tube of the Particle Number system) but also to non-volatile artifacts (i.e. non-volatile particles formed in the tubing between the vehicle and the particle number system or in the particle number system itself). In order to investigate the origin of the non-volatile particle formation, steady-state tests with a moped, a compressed natural gas (CNG) and a diesel vehicle while regenerating were conducted. Systems at the tailpipe and the dilution tunnel with evaporation tubes or catalytic strippers and condensation particle counters (CPCs) with 50% detection efficiencies at 2.5 nm, 4 nm, 10 nm, and 23 nm were used. The results showed higher concentrations of sub-23 nm particles at the dilution tunnel than at the tailpipe when the facility preconditioning was not appropriate, the exhaust gas temperature exceeded 300°C, and high concentrations of semi-volatile material were emitted (e.g. regenerations, lubricant oil).JRC.C.4 - Sustainable Transpor
Real Driving Emissions (RDE): Particle Number (PN) Portable Measurement Systems (PEMS) calibration
Full text linkThe PN-PEMS is considered a “black box” where efficiency tests and linearity have to be checked with thermally stable soot like aerosol. The efficiency is checked with monodisperse aerosol. The most straight forward way is to check the efficiency of the complete PN-PEMS but checking the thermal pre-conditioning unit and the particle detector of the PN-PEMS separately is also permissible. In the second case the two results have to be combined in one penetration efficiency. For the linearity check usually polydisperse aerosol is used in order to reach high concentration levels.JRC.C.4 - Sustainable Transpor
Fourier Transform Infrared (FTIR) Spectroscopy for Measurements of Vehicle Exhaust Emissions: A Review
No full textPollution from vehicles is a serious concern for the environment and human health. Vehicle emission regulations worldwide have limits for pollutants such as hydrocarbons, CO and NOx. The measurements are typically conducted at engine dynamometers (heavy-duty engines) sampling from the tailpipe or at chassis dynamometers (light-duty vehicles) sampling from the dilution tunnel. The latest regulations focused on the actual emissions of the vehicles on the road. Greenhouse gases (GHG) (such as CO2, CH4, N2O) and NH3 have also been the subject of some regulations. One instrument that can measure many gaseous compounds simultaneously is the Fourier transform infrared (FTIR) spectrometer. In this review the studies that assessed FTIRs since the ‘80s are summarized. Studies with calibration gases, or vehicle exhaust gas in comparison with well-established techniques were included. The main conclusion is that FTIRs, even when used at the tailpipe and not at the dilution tunnel, provide comparable results with other well-established techniques for CO2, CO, NOx, while for hydrocarbons higher deviations were noticed. The intro-duction of FTIRs in the regulation needs careful description of the technical requirements, espe-cially interference tests. Although the limited results of prototype portable FTIRs for on-road measurement are promising, their performance at the wide range of environmental conditions (temperature, pressure, vibrations) needs further studies.JRC.C.4 - Sustainable Transpor
EU project GasOn n.652816
Full text linkThe demo vehicle of Ford was measured at JRC in January 2019. In the laboratory the old type approval cycle NEDC and the new type approval cycle WLTC were tested. On the road RDE compliant routes were followed. The results showed that:
1. HC emissions were around half of the EU6 limit in NEDC and approximately 35% of the EU6 limit in the WLTC (not required for RDE).
2. NMHC emissions were in the range of 10% of the EU6 limit for both, the NEDC and the WLTC (not required for RDE).
3. CO emissions were about 20% of the EU6 limit in NEDC, approximately 50% of the EU6 limit in the WLTC and RDE and around 30% of the EU6d limit in RDE Urban.
4. NOx emissions were about 40% of the EU6 limit in NEDC, approximately 70% of the EU6 limit in the WLTC, around 85% of the EU6d limit in RDE and within the EU6d RDE Urban limit.
5. PN emissions were about 2% of the EU6 limit in NEDC, approximately 4% of the EU6 limit in the WLTC, below 20% of the EU6d limit in RDE and around 30% of the EU6d RDE Urban limit.
Conclusively, all pollutant emissions were below the respective 2020+ emissions limits in both, the laboratory tests (NEDC, WLTP) and on the road (RDE). Most are below 50% of the EU6d limit.JRC.C.4 - Sustainable Transpor
Particle Number Emissions of a Diesel Vehicle during and between Regeneration Events
No full textAll modern diesel vehicles in Europe are equipped with diesel particulate filters (DPFs) and their particle number (PN) emissions at the tailpipe are close to ambient air levels. After the Dieselgate scandal for high NOx emissions of diesel vehicles on the road, the high PN emissions during regeneration events are on the focus. The PN emissions of a diesel vehicle on the road and in the laboratory with or without regeneration events were measured using systems with evaporation tubes and catalytic strippers and counters with lower sizes of 23, 10 and 4 nm. The tests showed significant PN levels only during engine cold starts with a big fraction of sub-23 nm particles during the first minute. After the first seconds the sub-23 nm fraction was negligible. Urea injection at the selective catalytic reduction (SCR) for NOx system did not affect the PN levels and the sub-23 nm fraction. The emissions during regeneration events were higher than the PN limit, but rapidly decreased 2-3 orders of magnitude below the limit after the regeneration. Artificially high sub-10 nm levels were seen during the regeneration (volatile artifact) at the system with the evaporation tube. The regenerations were forced every 100–350 km and the overall emissions including the regeneration events were two to four times lower than the current laboratory PN limit. The results of this study confirmed the efficiency of DPFs under laboratory and on-road driving conditions
EU project GasOn contract n.652816
No full textThe demo vehicle of CRF was measured at JRC in summer 2018. In the laboratory the old type approval cycle NEDC and the new type approval cycle WLTC were tested. On the road RDE compliant routes were followed. The results showed that the vehicle fulfilled all Euro 6 limits except the NOx at the WLTC.JRC.C.4 - Sustainable Transpor
Gaseous and Particulate Emissions of a Euro 4 Motorcycle and Effect of Driving Style and Open or Closed Sampling Configuration
No full textAir pollution remains a serious concern for European citizens. The relative contribution of mopeds and motorcycles to air pollution started to increase as the levels from other vehicles started to decrease. The information on emission levels of Euro 4 motorcycles is limited because they were only recently introduced into the market (2016). In this study, the emissions of a 1 L Euro 4 motorcycle were determined with two drivers and two different sampling configurations (i.e., open or closed transfer tube to the dilution tunnel; both allowed in the current regulation). The motorcycle respected the current Euro 4 limits and even the future Euro 5 limits for most pollutants (CO 600 mg/km, NOx 48 mg/km, total hydrocarbons 60 mg/km). The particulate emissions, which are not regulated for this category of vehicles, were also very low and fulfilled the current limits of passenger cars (particulate mass < 0.5 mg/km, particle number 3 × 1011 p/km). The total particle emissions (i.e., including volatiles) were also low with the open configuration (6 × 1011 p/km). They increased more than one order of magnitude with the closed configuration due to desorption of deposited material from the transfer tube. For the gaseous pollutants, there was no significant difference between open or closed configuration (CO2 within 0.3%, rest pollutants 10%), but they were different between the two drivers (CO2 1.3%, rest pollutants 25%–50%). The main message from this work is that open and closed configurations are equivalent for gaseous pollutants but the open should be used when particles are measured
Theoretical Investigation of Volatile Removal Efficiency of Particle Number Measurement Systems
No full textEuro 5/6 light-duty vehicle emissions regulation introduced non-volatile particle number emission measurements. The particle number measurement system consists of a volatile removal unit followed by a particle number counter with a 50% cut-point diameter at 23 nm. The volatile removal unit must achieve a >99% concentration reduction of a monodisperse aerosol of tetracontane (CH3(CH2)38CH3) particles of diameter =30 nm with inlet concentration =104 cm-3. In this paper the evaporation of tetracontane particles in the volatile removal unit is investigated theoretically. The temperature and the residence time in the evaporation tube are discussed, as well as the possibility of nucleation events of evaporated particles at the exit of the evaporation tube. In addition, sulfuric acid nucleation at the evaporation tube exit is analyzed. Theoretical calculations are, finally, compared to experimental data. Our main conclusion is that the volatile removal efficiency requirements of the legislation can be easily met. However, as some experimental measurements showed, the removal efficiency might differ for large particle sizes and high concentrations; thus, the results of particle number counters with a 50% cut-point diameter less than 23 nm should be interpreted with care.JRC.DDG.H.4 - Transport and air qualit
Comparison of particle sizers and counters with soot-like, salt, and silver particles
No full textVehicle emission regulations in Europe and many Asian countries include a particle number limit. The number concentration is measured, typically, with condensation particle counters (CPCs). For research purposes, the size distributions provide useful information. Scanning mobility particle sizers (SMPSs) accurately provide the size distribution but are not suitable for transient aerosol. Engine (fast) exhaust particle sizers (EEPSs) cover this gap, but with less accuracy. Fast size distribution instruments are commonly used in the research and development of engines. In the last few years, instrument algorithms have been improved, but studies assessing the improvements are limited, in particular in their lower size range, around 10–20 nm, and for soot-like aerosol. In this paper, we compared the three instruments using salt, silver, diffusion flame soot (CAST), and spark discharge graphite particles. Moreover, vehicle exhaust number concentration measurements with EEPSs over a seven-year period were presented. In terms of particle concentration, an EEPS overestimated, on average, 25% compared to CPC, in agreement with previous studies. Its accuracy for mean particle size determination was better than 5 nm compared to SMPS. The agreement between the instruments was satisfactory but the uncertainty increased at low concentrations and larger particle sizes, showing that there is still room for further improvements.JRC.C.4 - Sustainable Transpor
A Note on the Comparison of Particle Number Counters
No full textComparison between two systems (methods) of measurement is predominantly performed by linear regression, which in some cases can be misleading. In this note we employ the example of comparing two particle number counters to show how the limits of agreement statistical approach, used extensively in clinical research, can be an alternative and more reliable way to compare methods.JRC.H.4 - Transport and air qualit
- …
