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Experimental determination of maximum effective hydrodynamic stress in multiphase flow using shear sensitive aggregates
Author(s) -
Villiger Thomas K.,
Morbidelli Massimo,
Soos Miroslav
Publication year - 2015
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.14753
Subject(s) - breakup , mechanics , bubble , turbulence , impeller , materials science , nozzle , shear stress , multiphase flow , aeration , stress (linguistics) , flow (mathematics) , thermodynamics , chemistry , physics , linguistics , philosophy , organic chemistry
Maximum effective hydrodynamic stress,τ max, responsible for the breakup of aggregates with size comparable to Kolmogorov eddies, was experimentally determined in an aerated stirred tank. The proposed method is based on the measurement of the maximum stable aggregates size consisting of poly(methyl methacrylate) nanoparticles. The fractal aggregates were broken under various operating conditions in an aerated stirred tank and calibrated with known flow conditions using contracting nozzles to convert the measured aggregate sizes into hydrodynamic stress. It was found thatτ max can vary substantially among studied conditions and its magnitude depends on the controlling mechanism including gas jet during bubble formation, bubble rise, bubble burst at the gas–liquid interface or the turbulence generated by the impeller. The measured values are in good agreement with literature data which supports the applicability of this method to characterize the maximum effective hydrodynamic stress in complicated multiphase flow. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1735–1744, 2015