Reducing the lower particle size cut point of a particle number emission measurement system: A holistic system optimization. The current Euro 6 standard limits the emission of non-volatile particle number (PN) for particles larger than 23 nm in diameter. Future European emission legislation for vehicle homologation will reduce the particle size limit to 10 nm in a first step for light-duty vehicles and subsequently for heavy duty vehicle types. In the European H2020 project “DownToTen” (DTT), critical loss mechanisms in the sub 23 nm regime were examined. Based on the findings, a loss-optimized dilution- and sampling system was demonstrated as a suitable exhaust particle probing unit for this size regime. We present the first steps beyond the project DownToTen incorporating the gained scientific findings into a commercially available state-of-the-art particle number measurement instrument. We substantially improved the AVL Particle Counter (APC) for the measurement of solid particles >10nm with respect to minimal losses and reduced artefact formation. This cannot be achieved by solely reducing the cut point of the employed counting unit. The primary dilution stage supplied by a Rotating Disk Diluter (RDD) was identified as a source of diffusional particle losses. The RDD’s particle loss performance was significantly improved by optimizations of the geometry and the mode of operation, theoretical calculations showed a potential loss reduction up to 45%. Flow path and flow rate optimizations reduced the diffusional particle losses in the system. First experiments showed a further 30% reduction. The performance of the optimized system was characterized experimentally and compared with simulation results.
|Publication status||Published - 19 Oct 2021|
|Event||39th Annual Meeting of the American Association for Aerosol Research - Virtuell, United States|
Duration: 18 Oct 2021 → 22 Oct 2021
|Conference||39th Annual Meeting of the American Association for Aerosol Research|
|Abbreviated title||AAAR 39th Annual Conference|
|Period||18/10/21 → 22/10/21|