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Updated: Jul 13, 2026

Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System
Published on: May 22, 2020
Influence of engine operating conditions on diesel particulate matter emissions in relation to transient and
Z Gerald Liu1, Denise C Ford, Victoria N Vasys
1Cummins Filtration and Emission Solutions, Stoughton, Wisconsin 53589, USA. jerry.z.liu@cummins.com
Abstract:
Airborne particulate matter is an important pollutant affecting air quality. Currently, diesel PM regulations are based on emitted particle mass; however, the particle size distributions are also important factors in air quality. While the distributions of particulate emissions under steady-state conditions are well-known and have been generalized, varying distributions undertransient conditions are not well-understood. This study investigates the size distributions of PM, focusing on the nuclei- and accumulation-modes, emitted from diesel engines under transient operations. Some engine conditions during transient testing produced particle size distributions that were notably different from those produced under steady-state conditions. During transient operation, the size distributions were either mono- or bimodal with peaks that were able to switch quickly between the nuclei- and accumulation-modes. These distributions have not been observed during steady-state testing but are significant because environmental and health effects and emission control solutions are highly dependent on particle size.
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