Image-Processing Based Gas Hold-Up and Mass Transfer Coefficients Measurements in Bubble Columns

Marwa Tariq Rasheed
Dr. Naseer A. Al-Habobi

  This thesis suggests a simple system to study, and accordingly design, bubble column reactors. The suggested system focuses on studying two important parameters of the gasliquid mass transfer operations. These two parameters were the gas hold-up and the interfacial surface area of one bubble.The system was tested with water as liquid and ambient air as the gas.The images taken were analyzed and manipulated through computer software to produce the required data.Images were manipulated through Adobe Photoshop 7.0 ME and two programs were made with MATLAB to extract the required data from these images.Three sets of results were obtained for three different diameters of the gas inlet; 0.15,0.10, and 0.08cm. The results were satisfying and the error in the measurement of interfacial surface area was 0.9%. The error in measuring the gas hold-up ranged from 8% and 15%.The measured gas hold-up for the gas inlet diameter of 0.15cm ranged between 0.65% and 1.84%. While for the 0.10cm gas inlet diameter, the gas hold-up ranged between 0.96% and 2.13%. And the gas hold-up for the 0.08cm gas inlet diameter lied in the range 1.2% to 2.38%.The measured average diameters of bubble for the gas inlet diameters of 0.15, 0.1, and 0.08cm were 0.21, 0.15, and 0.1cm, respectively.This system can be used for the analysis of hydrodynamics of stirred tank models as well as bubble columns. The apparatus used in this system were simple, inexpensive, and acceptably accurate.