Title :

A comparative study on effective density, shape factor, and volatile mixing of non-spherical particles using tandem aerodynamic diameter, mobility diameter, and mass measurements

Author(s) :

Kazemimanesh, Mohsen [Auteur]
University of Cambridge [UK] [CAM]
Rahman, Md Mostafizur [Auteur]
University of Cambridge [UK] [CAM]
Duca, Dumitru [Auteur]
Physique Moléculaire aux Interfaces [PMI]
Johnson, Tyler [Auteur]
University of Cambridge [UK] [CAM]
Addad, Ahmed [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Giannopoulos, George [Auteur]
University of Cambridge [UK] [CAM]
Focsa, Cristian [Auteur]
Physique Moléculaire aux Interfaces [PMI]
Boies, Adam [Auteur]
University of Cambridge [UK] [CAM]

Journal title :

Journal of Aerosol Science

Pages :

105930

Publisher :

Elsevier

Publication date :

2022

ISSN :

0021-8502

HAL domain(s) :

Chimie/Chimie théorique et/ou physique
Physique [physics]/Physique [physics]/Instrumentations et Détecteurs [physics.ins-det]
Sciences de l'environnement/Ingénierie de l'environnement

English abstract : [en]

Combustion-generated particles are typically non-spherical (soot aggregates) and sometimes mixed with organic compounds (e.g. in vehicle emissions). The effective density, dynamic shape factor, and volatile mixing of ...
Show more >Combustion-generated particles are typically non-spherical (soot aggregates) and sometimes mixed with organic compounds (e.g. in vehicle emissions). The effective density, dynamic shape factor, and volatile mixing of particles are widely studied using aerosol instruments that measure the particle mobility diameter, aerodynamic diameter, and mass. In theory, any of these three physical properties can be obtained from a combination of the other two. In the present study, a tandem arrangement of aerodynamic aerosol classifier (AAC; measuring aerodynamic diameter), differential mobility analyzer (DMA; measuring mobility diameter), optional catalytic stripper (CS), and centrifugal particle mass analyzer (CPMA; measuring particle mass) was used to study the effective density, dynamic shape factor, and volatile mixing of non-spherical non-homogenous particles. In terms of mass, the vast majority of the particles were purely semi-volatile mixed with soot with and without semi-volatile coating. The effective density of polydisperse non-stripped particles was relatively constant (indicating nearly spherical particles), while that of polydisperse stripped particles decreased from ∼1200 to ∼800 kg/m3 as the particle size increased (indicating a compact structure). The effective density of monodisperse particles, measured by DMA-CPMA, AAC-DMA, and AAC-CPMA methods, was consistent within the measurement uncertainty; however, the latter method had larger discrepancy with the other two methods, particularly for non-spherical particles. The dynamic shape factor, measured by AAC-CPMA and DMA-CPMA methods, increased with the mobility diameter, a trend also supported by electron micrographs. The volatile mass fraction of particles decreased as their mobility diameter increased, with smaller particles having volatile mass fraction of ∼20%. This result was further confirmed by chemical characterization of size-selected particles, proving the robustness of online aerosol measurements.Show less >

Language :

Anglais

Popular science :

Non

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL