Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Regime transition in viscous and pseudo viscous systems: A comparative study
Rabha, S.; Schubert, M.; Hampel, U.
A comprehensive quantitative study on the effect of liquid viscosity (1 ≤ µL ≤ 1149 mPa-s) on the local flow phenomena of the gas phase in a small diameter bubble column is performed using ultrafast electron beam X-ray tomography. The internal dynamic flow structure and the bubble size distribution have proven a dual role of the liquid viscosity on the hydrodynamics. Further, effect of solid concentration (Cs = 0.05, 0.20) on the local flow behavior of the gas phase is studied for the pseudo (slurry) viscosities similar to the liquid viscosities of the gas-liquid systems. The effects of liquid and pseudo (slurry) viscosity on flow structure, bubble size distribution and gas phase distribution are compared. The bubble coalescence is significantly enhanced with the addition of particles as compared to the system without particles for apparently same viscosity. The superficial gas velocity at which transition occurs from homogeneous bubbly to slug flow regime is initiated by the addition of particles as compared to the particle free system for apparently same viscosity.
Keywords: Liquid viscosity; Pseudo (slurry) viscosity; Gas holdup; Bubble size distribution; Ultrafast electron beam X-ray tomography
AIChE Journal 60(2014)8, 3079-3090
Online First (2014) DOI: 10.1002/aic.14528