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

Barouch Giechaskiel, Alessandro A. Zardini, Tero Lähde, Michael Clairotte, Fabrizio Forloni and Yannis Drossinos
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Barouch Giechaskiel: European Commission – Joint Research Centre, 21027 Ispra, Italy
Alessandro A. Zardini: European Commission – Joint Research Centre, 21027 Ispra, Italy
Tero Lähde: European Commission – Joint Research Centre, 21027 Ispra, Italy
Michael Clairotte: European Commission – Joint Research Centre, 21027 Ispra, Italy
Fabrizio Forloni: European Commission – Joint Research Centre, 21027 Ispra, Italy
Yannis Drossinos: European Commission – Joint Research Centre, 21027 Ispra, Italy

Energies, 2019, vol. 12, issue 22, 1-17

Abstract: 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 CO 2 ) 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 CO 2 ) 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.

Keywords: particle number; L-category; vehicle regulations; CO 2 emission; tailpipe measurements; dilution tunnel; accuracy; measurement uncertainty; motorcycles (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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