Impact of aggressive drive cycles on motor vehicle exhaust PM emissions

Maricq, M. Matti; Szente, Joseph J.; Harwell, Amy L.; Loos, Michael

doi:10.1016/j.jaerosci.2017.07.005

Cited by 40 publications

(18 citation statements)

References 27 publications

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“…As discussed elsewhere, the reproducibility of total PN measurements from the CVS is not good due to the variant dilution factor, the different flow rates employed at CVS, and the different residence times. In addition, the volatiles desorption from the transfer tubes to the CVS during high speed or aggressive cycles can result in unrealistically high values [107]. The opinion of the authors is that total PN should be conducted from the tailpipe under well-defined sampling conditions [154][155][156].…”

Section: Discussionmentioning

confidence: 99%

“…Most of the PM emitted by GDI vehicles is found to be EC (on average 80%; range: 45-95%). The high EC content is consistent since the introduction of GDIs in the markets: from early 2000s [93,95] to 2010s [94,100,[102][103][104][105][106][107][108][109]. The vehicle to vehicle variability masks any influence of test cycle, position of the injectors (side or top), or fuel injection strategy (stratified or stoichiometric) on the relative contribution of EC to PM.…”

Section: Chemical Compositionmentioning

confidence: 90%

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European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review

et al. 2019

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The particulate matter (PM) emissions of gasoline vehicles were much lower than those of diesel vehicles until the introduction of diesel particulate filters (DPFs) in the early 2000s. At the same time, gasoline direct injection (GDI) engines started to become popular in the market due to their improved efficiency over port fuel injection (PFI) ones. However, the PM mass and number emissions of GDI vehicles were higher than their PFI counterparts and diesel ones equipped with DPFs. Stringent PM mass levels and the introduction of particle number limits for GDI vehicles in the European Union (EU) resulted in significant PM reductions. The EU requirement to fulfill the proposed limits on the road resulted to the introduction of gasoline particulate filters (GPFs) in EU GDI models. This review summarizes the evolution of PM mass emissions from gasoline vehicles placed in the market from early 1990s until 2019 in different parts of the world. The analysis then extends to total and nonvolatile particle number emissions. Care is given to reveal the impact of ambient temperature on emission levels. The discussion tries to provide scientific input to the following policy-relevant questions. Whether particle number limits should be extended to gasoline PFI vehicles, whether the lower limit of 23 nm for particle number measurements should be decreased to 10 nm, and whether low ambient temperature tests for PM should be included.

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Section: Discussionmentioning

confidence: 99%

Section: Chemical Compositionmentioning

confidence: 90%

European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review

et al. 2019

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“…Formation of nonvolatile particles in the tubing between the vehicle and the dilution tunnel has only been speculated (Giechaskiel, Zardini, and Martini 2015b;Maricq et al 2017;Anderson 2018;Giechaskiel et al 2018). Here it was shown that it can happen and can influence sub-23 nm measurements.…”

Section: Reasons For Higher Concentrations At the Dilution Tunnelmentioning

confidence: 99%

Differences between tailpipe and dilution tunnel sub-23 nm nonvolatile (solid) particle number measurements

Giechaskiel

2019

Aerosol Science and Technology

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European Union vehicle and engine regulations require measurement of nonvolatile (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 nonvolatile artifacts (i.e., nonvolatile 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 nonvolatile 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 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).

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“…PFD_C was operated at 100 FFV for all tests because the system had an issue with flow stability at 130 FFV. [19]. Xue et al reported greater sensitivity of gravimetric method to more aggressive US06 cycle than FTP cycle [15].…”

Section: ''mentioning

confidence: 99%

Evaluation of Partial Flow Dilution Systems for Very Low PM Mass Measurements

Pham

Yang

Johnson

et al. 2018

Emiss. Control Sci. Technol.

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Particulate matter (PM) mass measurement methodologies were improved considerably with the application of Title 40 Code of Federal Regulations Part 1065 for the 2007 standards for heavy-duty engines that emphasized PM. However, there is still a need to improve the understanding of and the confidence in mass measurements for light-duty vehicles, which are now being subjected to more stringent PM standards. The purpose of this study is to evaluate commercially available partial flow dilutors (PFDs), with a particular focus on their equivalency with the standard constant volume sampler (CVS) tunnel method and the ability to provide reproducible measurements at low PM emission levels. For the main PFD comparison, simultaneous testing was conducted with the three PFDs, over federal test procedure (FTP) and US06 tests. The results of the calibrations and proportionality tests all showed good performance for the PFDs. The exhaust flow meters (EFMs) for the PFDs showed measurements within 2% or less of a calibration source. The PFDs also showed good level proportionality and can easily meet the CFR 1066 requirements for light-duty vehicles and 1065 requirements for all tests performed. Larger differences were seen for the main comparisons between the CVS and the different PFDs during the FTP testing, with the relative difference of PM emissions between the PFDs and the CVS varying from − 16.5 to − 0.6%, with an average pooled difference of − 8.5%. These FTP differences only represented 0.00 to 0.11 mg/mile on an absolute basis, however, and could be attributed to difficulties making and weighing filter mass measurements at such low levels. For the US06 cycle, the differences between the PFDs and the CVS were not statistically significant and ranged from − 6.7 to − 0.7% and up to 0.07 mg/mile.

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Impact of aggressive drive cycles on motor vehicle exhaust PM emissions

Cited by 40 publications

References 27 publications

European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review

European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review

Differences between tailpipe and dilution tunnel sub-23 nm nonvolatile (solid) particle number measurements

Evaluation of Partial Flow Dilution Systems for Very Low PM Mass Measurements

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