Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System

Area of Science:

• Environmental science
• Automotive engineering
• Aerosol science

Background:

• Current European Particle Number (PN) emission standards have a 23 nm threshold.
• Emerging vehicle technologies may produce significant sub-23 nm particle emissions, potentially bypassing current regulations.
• There is a need for advanced measurement techniques to characterize these smaller particles.

Purpose of the Study:

• To develop and validate a sampling and measurement method for characterizing particle emissions below the 23 nm threshold.
• To create a Portable Emission Measurement System (PEMS) for assessing sub-23 nm particles during Real Drive Emissions (RDE) testing.
• To enable the assessment of primary and secondary particles in the sub-23 nm range.

Main Methods:

• Conducted an extensive literature review to inform system development.
• Performed laboratory experiments to test various particle number measurement and sampling approaches.
• Developed a PEMS with high particle penetration and versatility for sub-23 nm particle characterization.

Main Results:

• A novel PN measurement system capable of characterizing particles from a few nanometers in diameter was successfully developed.
• The system demonstrates high particle penetration and versatility for assessing primary, delayed primary, and secondary aerosols.
• Instructions for installation and operation of the PEMS for RDE measurements are provided.

Conclusions:

• The developed PEMS effectively measures particle number emissions below the current 23 nm legislative limit.
• This technology is crucial for future regulatory frameworks addressing emerging combustion engine vehicle emissions.
• The DownToTen project provides a vital tool for assessing unregulated particle emissions.