Impacts of Exhaust Transfer System Contamination on Particulate Matter Measurements

Yang, Jiacheng; Pham, Liem; Johnson, Kent C.; Durbin, Thomas D.; Karavalakis, Georgios; Kittelson, David B.; Jung, Heejung

doi:10.1007/s40825-020-00155-1

Cited by 11 publications

(6 citation statements)

References 20 publications

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“…It can be assumed that the released material nucleated during cooling and dilution in the full dilution tunnel and resulted in high particle concentrations. Such desorption and high concentration of nucleation mode particles was reported in a dedicated study on the influence of the transfer line on particulate emissions [15]. In our study the geometric mean dimeter of these particles was 17-24 nm.…”

Section: Discussionsupporting

confidence: 80%

Emissions of a Euro 5 Motorcycle over the world harmonized motorcycle test cycle (WMTC)

Giechaskiel¹,

Melas²

2021

Combustion Engines

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The Euro 5 limits for L-category vehicles are applicable since 2020 and for this reason there is lack of studies examining the emissions of this category. In this study we tested a 1000 cm3 Euro 5 motorcycle over the World Harmonised Motorcycle Test Cycle (WMTC). The gaseous pollutants were approximately half of their respective limits. The cold start (first 2 minutes) contributed to the majority of the emissions. The solid particle number emissions were also 6.5 times below the limit for passenger cars, but the particles not counted with the current methodology were around 2 times higher. High concentrations of volatiles were emitted at the high speed part of the cycle.

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Section: Discussionsupporting

confidence: 80%

Emissions of a Euro 5 Motorcycle over the world harmonized motorcycle test cycle (WMTC)

Giechaskiel¹,

Melas²

2021

Combustion Engines

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“…At lower number concentrations in a few cases, higher percentages can be seen (the 80% values are from two WLTCs). The literature has also highlighted the need of stabilization time to the variability of the volatile particles measurements [56]: Many studies have found that it can take more than 1 h to stabilize the concentration of volatile particles [42,57], similar to what was demonstrated in our study. Other studies have also found higher concentration of volatile particles at the dilution tunnel compared to the tailpipe due to the desorption from the tube between the vehicle and the tailpipe [9,58].…”

Section: Emission Levelssupporting

confidence: 86%

Detailed Characterization of Solid and Volatile Particle Emissions of Two Euro 6 Diesel Vehicles

2022

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The solid particle number emissions of Diesel vehicles are very low due to the particulate filters as exhaust aftertreatment devices. However, periodically, the trapped particles are oxidized (i.e., active regeneration) in order to keep the backpressure at low levels. The solid particle number emissions during regenerations are only partly covered by the regulations. Many studies have examined the emissions during regenerations, but their contribution to the overall emissions has not been addressed adequately. Furthermore, the number concentration of volatile particles, which is not included in the regulations, can be many of orders of magnitude higher. In this study, the particulate emissions of two light-duty Euro 6 vehicles were measured simultaneously at the tailpipe and the dilution tunnel. The results showed that the weighted (i.e., considering the emissions during regeneration) solid particle number emissions remained well below the applicable limit of 6 × 1011 #/km (solid particles > 23 nm). This was true even when considering solid sub-23 nm particles. However, the weighted volatile particle number emissions were many orders of magnitude higher, reaching up to 3 × 1013 #/km. The results also confirmed the equivalency of the solid particle number results between tailpipe and dilution tunnel locations. This was not the case for the volatile particles which were strongly affected by desorption phenomena. The high number of volatiles during regenerations even interfered with the 10 nm solid particle number measurements at the dilution tunnel, even though a catalytic stripper equipped instrument was also used in the dilution tunnel.

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“…Even though we used one filter for the whole campaign to minimize volatile artifacts on the filter, the PN/PM ratio was 3.8-4.8 × 10 11 p/mg, lower than the typically expected 1-2 × 10 12 p/mg, indicating that the contribution of volatiles was significant. We suspect that the origin is released material from the transfer tube to the dilution tunnel during the high exhaust gas temperature regeneration events [88].…”

Section: Pn Instrumentationmentioning

confidence: 99%

Assessment of Gaseous and Particulate Emissions of a Euro 6d-Temp Diesel Vehicle Driven >1300 km Including Six Diesel Particulate Filter Regenerations

Valverde

Giechaskiel

2020

Atmosphere

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Diesel-fueled vehicles have classically had high particulate and NOx emissions. The introduction of Diesel Particulate Filters (DPFs) and Selective Catalytic Reduction for NOx (SCR) systems have decreased the Particle Number (PN) and NOx emissions, respectively, to very low levels. However, there are concerns regarding the emissions released during the periodic DPF regenerations, which are necessary to clean the filters. The absolute emission levels and the frequency of the regenerations determine the contribution of regenerations, but where they happen (city or highway) is also important due to different contributions to human exposure. In this study, we measured regulated and non-regulated emissions of a Euro 6d-temp vehicle both in the laboratory and on the road. PN and NOx emissions were similar in the laboratory and on-the road, ranging around 1010 p/km and 50 mg/km, respectively. Six regeneration events took place during the 1300 km driven, with an average distance between regeneration events of only 200 km. During regeneration events, the laboratory limits for PN and NOx, although not applicable, were exceeded in one of the two measured events. However, the on-road emissions were below the applicable not-to-exceed limits when regenerations occurred. The weighted PN and NOx emissions over the regeneration distance were approximately two times below the applicable limits. The N2O emissions were <14 mg/km and NH3 at instrument background level (<1 ppm), reaching 8 ppm only during regeneration. The results of this study indicate that due to the short interval between regenerations, studies of diesel vehicles should report the emissions during regeneration events.

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Impacts of Exhaust Transfer System Contamination on Particulate Matter Measurements

Cited by 11 publications

References 20 publications

Emissions of a Euro 5 Motorcycle over the world harmonized motorcycle test cycle (WMTC)

Emissions of a Euro 5 Motorcycle over the world harmonized motorcycle test cycle (WMTC)

Detailed Characterization of Solid and Volatile Particle Emissions of Two Euro 6 Diesel Vehicles

Assessment of Gaseous and Particulate Emissions of a Euro 6d-Temp Diesel Vehicle Driven >1300 km Including Six Diesel Particulate Filter Regenerations

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