Chemical Engineering Research & Design, Vol.156, 108-130, 2020
Bubble size distribution and specific bubble interfacial area in two-phase microstructured dense bubbling bed
The present work reports the investigation of flow regime, bubble size and its distribution, bubble aspect ratio and interfacial area in three distinct axial zones of the microstructured column in the presence and absence of the surfactant. The effect of surfactant type (i.e., cationic and anionic), superficial gas velocity, viscosity (in the presence of carboxymethyl cellulose), and the axial zone is investigated thoroughly. The image analysis technique is used to measure the bubble size in the gas distributor region and region of fully developed flow in the column. The bubble size distribution is found to vary with different experimental conditions, and it follows the log-logistic and beta distribution function. The observed results show that the change in the surface tension, axial zone, and viscosity of the system change the bubble shape and size, which alters the bubble size distribution, thus, enhance the interfacial area. Correlations are developed by considering the operating (i.e., gas velocity) and geometric variables (viz., column geometry, aspect ratio), and physicochemical properties (i.e., surface tension, viscosity, density) of the system for all the distribution parameters of the distribution function. Generalized empirical correlations are also proposed to interpret the Sauter mean bubble diameter, aspect ratio and specific interfacial area for dense bubbly flows. The predicted results are in good agreement with the experimental data. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.