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

Abstract

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.

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

“…Recently, it was also suggested that these sub-23 nm particles are nonvolatile in nature as their concentration did not change with different dilutions or using catalytic stripper [85]. Elastomer connectors, which was not the case at our tests, can release non-volatile particles at elevated temperatures [86]. Another possibility is that these particles consist of compounds with boiling points around 350 °C, which is the temperature of the evaporation tube of the PN system.…”

Comparisons of Laboratory and On-Road Type-Approval Cycles with Idling Emissions. Implications for Periodical Technical Inspection (PTI) Sensors

“… PN-PEMS studies: Laboratory studies that compared PN-PEMS with PMP systems at the tailpipe or the dilution tunnel [ 30 , 31 , 32 , 33 ]. From the studies that investigated the 10 nm PEMS, only the 23 nm information was used [ 34 , 35 ]. Tailpipe studies: Laboratory studies that compared PMP systems at the tailpipe and the dilution tunnel [ 28 , 36 ].…”

“…PN-PEMS studies: Laboratory studies that compared PN-PEMS with PMP systems at the tailpipe or the dilution tunnel [ 30 , 31 , 32 , 33 ]. From the studies that investigated the 10 nm PEMS, only the 23 nm information was used [ 34 , 35 ].…”

Assessment of 10-nm Particle Number (PN) Portable Emissions Measurement Systems (PEMS) for Future Regulations

“…The intention is to include the new methodology in the Global Technical Regulation (GTR) 15 for light-duty vehicles and in the near future apply it in the EU regulation. However, the research for PEMS fulfilling the future requirements is limited [39]. Most importantly, it is still not known how much the measurement uncertainty will be affected by the extension of the lower size from 23 nm to 10 nm.…”