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Title: Study of bubble column hydrodynamic phenomena using direct imaging technique.
Authors: Md. Iqbal Hossain
Keywords: DRNTU::Engineering::Chemical engineering
Issue Date: 2011
Abstract: The main objective of the present study is to improve the direct imaging technique in bubble size and size distribution measurement. A statistical method is developed to account for the change in object (object refers to discrete phase of particles, gas bubbles, or liquid droplets) magnification within any known depth-of-field, DOF. The developed statistical method is intended to improve the direct imaging technique by eliminating the need of shallow DOF, reducing the sampling time, and reducing the errors with results. The statistical method is verified experimentally. The stability of the statistical method has been evaluated theoretically with various degree of change in magnification, focus adjustment, DOF, accuracy of the used DOF, number of distribution bins, selection of continuous distribution function, and measurement deficiency (MD), etc. The accuracy of the used DOF is theoretically found to govern the accuracy of ultimate results. Hence, the effect of object concentration on the DOF is evaluated using borescope imaging (a specific direct imaging) technique. Subsequently, a DOF model is developed to allow the prediction of accurate DOF at various object concentrations. Finally, the borescope imaging technique integrated with both the developed statistical method and DOF model is applied in a bubble column. The individual effects of column operating pressure and gas velocity on the bubble size and size distribution are studied. The difference in bubble size and size distribution between the fully developed and near gas distributor regions of a column is also studied. The achievement of the desired bubble size and size distribution can be disturbed by the liquid weeping phenomenon. In addition, an increase in pressure drop and column operating cost can be caused from the presence of liquid weeping. Hence, methodologies to suppress the liquid weeping are explored. An image analysis algorithm is also developed to examine the weeping and its relevant process automatically employing the direct imaging technique.
Description: 207 p.
Rights: Nanyang Technological University
Fulltext Permission: restricted
Fulltext Availability: With Fulltext
Appears in Collections:SCBE Theses

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