19ENV09 MetroPEMS: Improved vehicle exhaust quantification by portable emission measurement systems metrology

• Forschungsstelle: METAS
• Projektnummer: F-5235.30138

Schlüsselwörter (Englisch)

silver particle generator (SPG), aerosol counters, particle counters, reference aerosol generation, condensation particle counter, differential mobility analyzer, instrument calibration

Projektziele (Englisch)

Characterize reference aerosols produced by the silver particle generator. 

Abstract (Englisch)

The performance of the new Silver Particle Generator (SPG) from Catalytic Instruments (Germany) was characterized in the laboratory. SPG generated high particle densities of up to ∼1.78 × 10¹⁰ cm⁻³ of thermally stable, solid, monomodal/monodisperse, and size-controlled aerosols. The default settings allowed the immediate selection from two operation points (Mode 1 and Mode 2). Aerosol size distributions from both modes showed high aerosol densities in the designated size ranges and in most cases the geometric mean mobility diameter (GMD_mob) of the aerosols exhibited an intraday stability and day-to-day reproducibility in particle size within 4%. Changes in internal dilution settings allowed fine-tuning of aerosol densities and GMD_mob.

Based on TEM measurements, particles from Mode 1 were spherical even when default settings (air as carrier/dilution gas) were applied and had a GMD_mob of 5-6 nm, whereas larger particles from Mode 2 (GMD_mob of approx. 14 nm) possessed a compact, but not perfectly spherical shape. Substitution of air as the carrier/dilution gas by N₂ and additional sintering at 800 °C allowed the conversion of not perfectly round particles from Mode 2 to spherical and reduced the GMD_mob to approx. 8 nm. Therefore, aerosol from both Modes (GMD_mob ranging from <5 nm to at least 20 nm) can be considered as standard aerosol that can be applied to the calibration of CPCs (condensation particle counters) and DMAs (differential mobility anlyzers) or the characterization of other instruments used in air quality monitoring. 

Umsetzung und Anwendungen (Englisch)

SPG is currently being used for the calibration of CPCs and DMAs as well as in research projects involving PN-PEMS (Particle Number-Portable Emissions Measurement System) and particle counters based on diffusion charging.   

Publikationen / Ergebnisse (Englisch)

Hammer, T., Irwin, M., Swanson, J., Berger, V., Sonkamble, U., Boies, A., Schulz, H. and Vasilatou, K. (2022) 'Characterising the silver particle generator; a pathway towards standardising silver aerosol generation', Journal of Aerosol Science, Vol. 163, no. 105978, doi.org/10.1016/j.jaerosci.2022.105978

Vasilatou, K., Wälchli, C., Auderset, K., Burtscher, H., Hammer, T., Giechaskiel, H. and Melas, A. (2023) 'Effects of the test aerosol on the performance of periodic technical inspection particle counters', Journal of Aerosol Science, Vol. 172, no. 106182, doi.org/10.1016/j.jaerosci.2023.106182