Webinar: Vehicle particulate emissions measurement

October 15, 2020

Particulate emissions from motor vehicles is an essential study owing to the associations observed between ambient particulate matter (PM) levels and health effects. Ultra-fine particles are potentially more injurious to human health than coarse particles, owing to their ability to translocate to the bloodstream through the lungs. This has led to emissions regulations and stringent standards and the investigation has broadened to include non-road engines. The webinar will review instruments that are capable of real time measurement, enhanced sensitivity, on-board vehicle operation, sampling methods and an understanding of the characteristics of the instrument employed. It is generally recognized that the exhaust aerosol concentration measured depends on both the sampling technique and the instrument used.

The Electrical Low Pressure Impactor (ELPI) was introduced at the beginning of 1990s for vehicle exhaust particulate emission measurements and has evolved over the years. The ELPI measurement is based on the charging of particles and electrical detection of charged particles in a low-pressure impactor. It is capable of measuring emission particles with aerodynamic diameters between 6 nm and 10 μm and classifies them into 14 stages according to their sizes through particle charging and inertial classification mechanisms. The high-temperature ELPI+ is used to perform online real-time measurements of particle size-resolved distributions, PN, and quantity concentrations. The ELPI heating unit enables sampling of vehicle exhaust straight to the impactor without using any dilution and hence avoids the interference to measurement results due to dilution and improves sensitivity.

The non-exhaust emissions are believed to constitute the majority source of primary particulate matter from road transport (PM2.5 and PM10). While regenerative braking is expected to reduce brake wear emissions, the increased weight and torque characteristics of alternative drivetrains such as EVs will likely be associated with increased tyre wear. Until recently high particle number count has typically either not been measurable or not been measured, owing to a regulatory preoccupation with mass and a lack of suitably sensitive real-time measurement instrumentation. A heavier vehicle increases tyre wear, whereas light weighting mitigates it. This has implications for the broader market trend towards SUVs, where often particularly large rim tyre sizes are adopted. Tyres would be regulated more, and perhaps also reinvented for electric cars to perform well in durability and noise in future.

We hoped you enjoyed our webinar “Vehicle particulate emissions measurement” as much as we did! If you weren’t able to make it, catch our replay.



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