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Effect of flow field heterogeneity in coagulators on aggregate size and structure
Author(s) -
Ehrl Lyonel,
Soos Miroslav,
Wu Hua,
Morbidelli Massimo
Publication year - 2010
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.12179
Subject(s) - radius of gyration , scaling , turbulence , radius , power law , mechanics , aggregate (composite) , intensity (physics) , exponent , materials science , chemistry , thermodynamics , physics , mathematics , optics , composite material , geometry , statistics , polymer , linguistics , computer security , philosophy , computer science
Aggregate size and structure were investigated under turbulent conditions in stirred tank (ST) and Taylor–Couette‐type (TC‐type) devices. Root‐mean‐square radius of gyration, 〈 Rg 〉, and zero‐angle intensity of scattered light, I(0), were acquired as a function of stirring intensity, characterized by an experimentally obtained average hydrodynamic stress, 〈τ〉 exp , determined by torque measurements. Evaluating aggregate images revealed that aggregate structure and shape are independent of the device type. However, in TC‐type devices, the aggregates grow to three to four times larger sizes than inside ST, although the same 〈τ〉 exp was used in both coagulators. As confirmed by computational fluid dynamics, this can be attributed to the differences in the maximum hydrodynamic stress in ST compared with those in TC‐type devices. In contrast, the power‐law scaling of 〈 Rg 〉 and I(0) with 〈τ〉 exp is preserved for all investigated devices, with an exponent approximately equal to −0.5 and −0.7, respectively. © 2010 American Institute of Chemical Engineers AIChE J, 2010