Particle Number Measurements Directly from the Tailpipe for Type Approval of Heavy-Duty Engines

Giechaskiel, Barouch; Lähde, Tero; Schwelberger, Matthias; Kleinbach, Timo; Roske, H.; Teti, Enrico; Bos, Tim van den; Neils, Patrick; Delacroix, Christophe; Jakobsson, Tobias; Karlsson, Hua Lu

doi:10.3390/app9204418

Cited by 24 publications

(16 citation statements)

References 39 publications

(43 reference statements)

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“…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]. A lot of concerns have also been raised for engines fueled with compressed natural gas (CNG) [23,25].…”

Section: Introductionmentioning

confidence: 99%

“…Based on these findings, the PMP (particle measurement programme) group of the working party on pollution and energy (GRPE) of the United Nations Economic Commission for Europe (UNECE) is working on a protocol to lower the 23 nm cut-off point to 10 nm [26]. The first prototype laboratory instruments were used for inter-laboratory correlation exercises [24,26]. The draft specifications, which are based on existing systems, will be finalized in 2020.…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

confidence: 99%

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

Giechaskiel

Mamakos

Woodburn

et al. 2019

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…Tests with heavy-duty diesel and CNG (compressed natural gas) engines with cold and hot dilution showed similar results with 23 nm and 10 nm CPCs. Thus, we expect small effect if any also for mopeds and motorcycles [49]. Dedicated studies have shown that particles may be formed or grow to the measurement range of instruments from the silicone, Teflon parts, or desorbed material of the transfer tube when the exhaust gas temperature is high.…”

Section: Discussionmentioning

confidence: 90%

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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“…It should also be mentioned that part of the measurement uncertainty value used in the regulation comprises the particle losses between tailpipe (i.e., PEMS sampling location) and dilution tunnel (i.e., laboratory-grade equipment sampling location). There is an intention to permit SPN laboratory measurements for type approval also from the tailpipe [30,88]. This will further decrease the uncertainty from the different locations (at the moment estimated 20–25%).…”

Section: Discussionmentioning

confidence: 99%

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

Giechaskiel

Bonnel

Perujo

et al. 2019

IJERPH

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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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Particle Number Measurements Directly from the Tailpipe for Type Approval of Heavy-Duty Engines

Cited by 24 publications

References 39 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)

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

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

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