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Dependence of initial cluster aggregation kinetics on shear rate for particles of different sizes under turbulence
Author(s) -
Ehrl Lyonel,
Soos Miroslav,
Morbidelli Massimo,
Bäbler Matthäus Ulrich
Publication year - 2009
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.11923
Subject(s) - dimensionless quantity , radius of gyration , turbulence , chemistry , shear rate , particle (ecology) , mechanics , thermodynamics , statistical physics , physics , polymer , rheology , oceanography , organic chemistry , geology
Abstract Initial aggregation kinetics for three particle sizes and broad range of Péclet numbers were investigated under turbulent conditions in stirred tank. This allowed us to observe the transition from diffusion‐controlled to purely shear‐induced aggregation. The evolution of the root‐mean‐square radius of gyration, zero‐angle intensity of scattered light, and obscuration was obtained by small‐angle static light scattering. For a given particle size the measured evolution of all integral quantities obtained for various volume average shear rates 〈 G 〉, scales with a dimensionless time, τ exp = α exp × 〈 G 〉 × ϕ × t . The experimentally obtained aggregation efficiency α exp , follows the power law α exp = Pe − n , where Pe is the primary particle Péclet number. With increasing particle size a decrease in n is observed in accordance with theory and literature data. As previously predicted by population balance equation simulations three aggregation regimes were observed experimentally. © 2009 American Institute of Chemical Engineers AIChE J, 2009