A novel image processing technique for detection of pseudo occluded bubbles and identification of flow regimes in a bubble column reactor

Abstract

Pseudo bubble occlusion is a challenging situation for an image analysis tool as it involves a 2D projection of a 3D object. In this work, a robust algorithm has been developed to detect the bubbles from pseudo occlusion. Images of the flow are captured using a high-speed camera. The algorithm employed for bubble detection comprises Adaptive Threshold-based Image Segmentation which comprises segmentation, edge detection, segment grouping, and ellipse fitting. The bubble size is detected and the bubble size distributions for different air flow rates are obtained. The regime identification has been done based on the cell averaged projected void fraction, bubble dimensions, and the distribution of the bubbles. As the superficial air velocity increases in the range of 0–2 cm/s, bubble break up becomes prominent, and hence, the number of smaller size bubbles increases.