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Coagulation of aerosol agglomerates in the transition regime

Rogak, Steven N. and Flagan, Richard C. (1992) Coagulation of aerosol agglomerates in the transition regime. Journal of Colloid and Interface Science, 151 (1). pp. 203-224. ISSN 0021-9797. doi:10.1016/0021-9797(92)90252-H.

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Aerosol agglomerates are produced by homogeneous nucleation and Brownian coagulation. Coagulation models developed previously for spheres may be applicable to the initial stages of growth in which the colliding particles coalesce rapidly. Particles larger than a critical size d_1 are expected not to coalesce, leading to the formation of fractal-like agglomerates of dense primary particles. To describe coagulation in such systems, it is necessary to predict the mobilities, collision diameters, and mean free paths of agglomerate particles having sizes comparable to the gas mean free path λ. Using existing data on particle mobility and structure, these quantities are obtained for model agglomerates with fractal dimensions D_f in the range 1 < D_f < 3. For D_f ∼ 1.8, the resulting coagulation-frequency function K is found to be significantly higher than for spheres with the same mobility and material density ρ, in part because of the low effective density of the agglomerates. Numerical solutions of the coagulation equation show that as the aerosol grows from coalescing particles past the critical primary-particle size d1, both the width of the size distribution, σ_g, and the coagulation rate increase. For aerosols where the average particle is much larger than f_1, both σg and the coagulation rate are reduced. Although the growth is affected by D_f, f_1, λ, and ρ, results for large agglomerates are consistent with similarity solutions using a simplified collision-frequency function. For the simplified coagulation-frequency function it is assumed that the agglomerates are smaller than λ but much larger than the agglomerate mean free paths.

Item Type:Article
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URLURL TypeDescription
Rogak, Steven N.0000-0002-4418-517X
Flagan, Richard C.0000-0001-5690-770X
Additional Information:© 1992 Elsevier. Received May 8, 1991; accepted November 13, 1991. This research was supported by the International Fine Particle Research Institute and by the U.S. Department of Energy under Grants DE-FG22-90PC90286 and DE-AC22-86PC90751. Comments made by B. Dominik and B. Wyslouzil during the preparation of this work are greatly appreciated.
Funding AgencyGrant Number
International Fine Particle Research InstituteUNSPECIFIED
Department of Energy (DOE)DE-FG22-90PC90286
Department of Energy (DOE)DE-AC22-86PC90751
Issue or Number:1
Record Number:CaltechAUTHORS:20150805-112114047
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Official Citation:Steven N Rogak, Richard C Flagan, Coagulation of aerosol agglomerates in the transition regime, Journal of Colloid and Interface Science, Volume 151, Issue 1, June 1992, Pages 203-224, ISSN 0021-9797,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59228
Deposited By: Irina Meininger
Deposited On:09 Dec 2015 20:32
Last Modified:19 Apr 2023 23:00

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