RESEARCH ARTICLE
Theoretical Analyses of Aerosol Aging on a Substrate without Wall-Effects by a Cross-Flow
James P. Cowin†, 1, Xin Yang‡, 1, Xiao-Ying Yu*, 2, Martin J. Iedema3
Article Information
Identifiers and Pagination:
Year: 2011Volume: 5
First Page: 106
Last Page: 113
Publisher Id: TOASCJ-5-106
DOI: 10.2174/1874282301105010106
Article History:
Received Date: 25/7/2011Revision Received Date: 28/8/2011
Acceptance Date: 29/08/2011
Electronic publication date: 14/12/2011
Collection year: 2011
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Long time (~1day) aging or reactions of aerosol is typically studied using either large aerosol chambers (>10 m3) or particles supported on a substrate to minimize wall effects. To avoid wall effects in the latter, it is often essential that the wall reactivity be extremely small (<10-5 reactions per encounter) and that the particle loadings be very small (<1 pg/cm2) to eliminate transport-limited trace gas depletion near the particles and substrate. We evaluate here a cross-flow approach, which greatly reduces these constraints. Particles are to be supported on a micromesh (~50% or more open area) through which the reactive gas is drawn at around a few hundred cm/s. The analysis shows how the competitions between flow and diffusion establishes a “zone of isolation” several microns wide around each reactive particle, outside of which the reactivity of other particles or the substrate is irrelevant to the local reactions. This cross-flow approach reduces the effects of substrate and collective particle reactivity typically orders of magnitude, and will facilitate aging studies of supported aerosols.