Particulate Emissions of Euro 4 Motorcycles and Sampling Considerations

Giechaskiel, Barouch; Zardini, Alessandro; Lähde, Tero; Perujo, A.; Kontses, Anastasios; Ntziachristos, Leónidas

doi:10.3390/atmos10070421

Cited by 16 publications

(22 citation statements)

References 51 publications

(133 reference statements)

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“…A recent review found that PFI vehicles can exceed the PN limit, but also that the concentration of particles not counted can be as high as of those >23 nm [20]. Mopeds and motorcycles have also high sub-23 nm percentages [21,22]. Finally, heavy-duty vehicles were found to emit high sub-23 nm concentrations [9,23], which were sometimes >7 times the >23 nm levels [24].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a 10 nm Particle Number Portable Emissions Measurement System (PEMS)

Giechaskiel

Mamakos

Woodburn

et al. 2019

Sensors

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On-board portable emissions measurement systems (PEMS) are part of the type approval, in-service conformity, and market surveillance aspects of the European exhaust emissions regulation. Currently, only solid particles >23 nm are counted, but Europe will introduce a lower limit of 10 nm. In this study, we evaluated a 10-nm prototype portable system comparing it with laboratory systems measuring diesel, gasoline, and CNG (compressed natural gas) vehicles with emission levels ranging from approximately 2 × 1010 to 2 × 1012 #/km. The results showed that the on-board system differed from the laboratory 10-nm system on average for the tested driving cycles by less than approximately 10% at levels below 6 × 1011 #/km and by approximately 20% for high-emitting vehicles. The observed differences were similar to those observed in the evaluation of portable >23 nm particle counting systems, despite the relatively small size of the emitted particles (with geometric mean diameters <42 nm) and the additional challenges associated with sub-23 nm measurements. The latter included the presence of semivolatile sub-23 nm particles, the elevated concentration levels during cold start, and also the formation of sub-23 nm artefacts from the elastomers that are used to connect the tailpipe to the measurement devices. The main conclusion of the study is that >10 nm on-board systems can be ready for introduction in future regulations.

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Section: Introductionmentioning

confidence: 99%

Evaluation of a 10 nm Particle Number Portable Emissions Measurement System (PEMS)

Giechaskiel

Mamakos

Woodburn

et al. 2019

Sensors

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“…In the previous study with the same moped [11] a counter with 50% counting efficiency of 2.5 nm still could not detect these particles at the tailpipe. With the instrumentation of this and the previous studies [11,25] the penetration of 4 nm particles is <5%, rendering it practically impossible to detect 1-3 nm nanoclusters and to determine whether the particles detected in the CVS are already present at the tailpipe even after cold dilution. Systems with relatively low particle losses [10] that can detect from 1 nm [26] would be necessary to investigate the existence of these particles at the tailpipe and distinguish the contribution of the vehicle from the transfer tube.…”

Section: Discussionmentioning

confidence: 77%

“…Although this study focused on a moped, formation of sub-23 nm particles was reported with motorcycles [25], a CNG (compressed natural gas) vehicle, and a diesel one during regeneration of the DPF (diesel particulate filter) [11]. Thus, attention is necessary when the exhaust gas temperature is high (on the order of 300 • C) and low volatility compounds are present either from the vehicle or the transfer tube.…”

Section: Discussionmentioning

confidence: 98%

“…The reason that the particles are were not evaporated in the evaporation tube at 350 • C is due to their low volatility and kinetic restrictions (finite residence time in the evaporation tube) of the particle number measurement system [24]. This can partly explain why the nonvolatile particles were seen with the mopeds (residence time 15 s) [11], a motorcycle (residence time 3.5 s) [25], and less with another one (residence time 2.8) [25]. Pyrolysis as a mechanism of formation can be excluded, because increasing the temperature of the transfer tube from 80 • C to 150 • C did not increase or accelerate the formation or growth of these particles.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Sampling Conditions on the Sub-23 nm Nonvolatile Particle Emissions Measurements of a Moped

Giechaskiel

2019

Applied Sciences

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The solid (or nonvolatile) particle number (SPN) emissions of light-duty and heavy-duty vehicles and engines are regulated in the European Union. The measurements are conducted from the tailpipe during on-road tests, but from the dilution tunnel in the laboratory under controlled conditions. Recently, dedicated laboratory studies for the evaluation of the measurement uncertainty at the two sampling locations found differences due to the formation of nonvolatile particles, i.e., particles that do not evaporate in the thermal pre-treatment part of the particle number systems. In order to investigate the origin of these particles, measurements at the tailpipe, the transfer tube, and the dilution tunnel were conducted with cold and hot dilution and instruments with different lower detection limits (4 nm, 10 nm, and 23 nm). The results showed that sub-23 nm nonvolatile particles could be detected in the dilution tunnel, but not at the tailpipe, due to growth of low volatility compounds in the transfer tube and the finite residence time in the thermal pretreatment part of the particle number systems. When measuring below 23 nm, diluting at the tailpipe or reducing the residence time in the transfer tube to the dilution tunnel is important in order to minimize such differences.

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“…Consequently, a specific particle number limit should be considered for L-category vehicles. A recent study with the latest technology mopeds and motorcycles (all fulfilling the Euro 4 emission standards) reported that, although the PM mass emissions were <1.5 mg/km for all vehicles tested, two motorcycles and the moped were close to the SPN limit for passenger cars and four motorcycles exceeded the limit by a factor of up to four [13]. Even though the repeatability was good (about 10% deviation from the mean), steady state tests with the moped showed big differences between the tailpipe and the dilution tunnel sampling points for sub-23 nm particles.…”

Section: Introductionmentioning

confidence: 92%

Identification and Quantification of Uncertainty Components in Gaseous and Particle Emission Measurements of a Moped

et al. 2019

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The recent Euro 4 and 5 environmental steps for L-category vehicles (e.g., mopeds, motorcycles) were mainly designed to reduce the emissions of particulate matter and ozone precursors, such as nitrogen oxides and hydrocarbons. However, the corresponding engine, combustion, and aftertreatment improvements will not necessarily reduce the solid particle number (SPN) emissions, suggesting that a SPN regulation may be necessary in the future. At the same time, there are concerns whether the current SPN regulations of passenger cars can be transferred to L-category vehicles. In this study we quantified the errors and uncertainties in emission measurements, focusing on SPN. We summarized the sources of uncertainty related to emission measurements and experimentally quantified the contribution of each uncertainty component to the final results. For this reason, gas analyzers and SPN instruments with lower cut-off sizes of 4 nm, 10 nm, and 23 nm were sampling both from the tailpipe, and from the dilution tunnel having the transfer tube in closed or open configuration (i.e., open at the tailpipe side). The results showed that extracting from the tailpipe 23–28% of the mean total exhaust flow (bleed off) resulted in a 24–31% (for CO2) and 19–73% (for SPN) underestimation of the emissions measured at the dilution tunnel. Erroneous determination of the exhaust flow rate, especially at cold start, resulted in 2% (for CO2) and 69–149% (for SPN) underestimation of the tailpipe emissions. Additionally, for SPN, particle losses in the transfer tube with the closed configuration decreased the SPN concentrations around 30%, mainly due to agglomeration at cold start. The main conclusion of this study is that the open configuration (or mixing tee) without any instruments measuring from the tailpipe is associated with better accuracy for mopeds, especially related to SPN measurements. In addition, we demonstrated that for this moped the particle emissions below 23 nm, the lower size currently prescribed in the passenger cars regulation, were as high as those above 23 nm; thus, a lower cut-off size is more appropriate.

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Particulate Emissions of Euro 4 Motorcycles and Sampling Considerations

Cited by 16 publications

References 51 publications

Evaluation of a 10 nm Particle Number Portable Emissions Measurement System (PEMS)

Evaluation of a 10 nm Particle Number Portable Emissions Measurement System (PEMS)

Effect of Sampling Conditions on the Sub-23 nm Nonvolatile Particle Emissions Measurements of a Moped

Identification and Quantification of Uncertainty Components in Gaseous and Particle Emission Measurements of a Moped

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