Comparative assessment of different image processing methods to determine the gas–liquid interfacial area in froth regimes of sandwich packings from ultrafast X-ray tomography image data

• Published in: Chemical engineering research & design Vol. 147; pp. 676 - 688
• Main Authors: Sohr, J., Bieberle, M., George, G.R., Flechsig, S., Kenig, E.Y., Schubert, M., Hampel, U.
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01-07-2019; Elsevier Science Ltd
• Subjects: Cross-sections; Fluid dynamics; Gas-liquid interfacial area; Gases; Image processing; Image processing systems; Image segmentation; Liquid flow; Post-production processing; Sandwich packing; Tomography; Two phase flow; Ultrafast X-ray tomography; X ray imagery; Image segmentation; Gas-liquid interfacial area; Ultrafast X-ray tomography; Sandwich packing
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2019.05.039

•Ultrafast X-ray tomography is used to visualize froth-like flow in parts of sandwich packings.•Gas–liquid interfaces in dynamic froth flow can be extracted by a modified level set method.•Interfacial area density decreases with increasing liquid load but is independent from gas load.
Sandwich packings consist of alternatingly stacked structured packing layers of different specific surface area. In such packings froth two-phase flow appears when the packing is operated between the loading limits of the layers. For this highly agitated flow regime, there is a lack of hydrodynamic data, in particular on gas-liquid interfacial area. Ultrafast X-ray tomography, a cross-sectional imaging technique with a frame rate of more than 1000 cross-sectional images per second, is applied to visualize the gas-liquid flow and to extract the gas–liquid interfacial area data via image post-processing methods. For that, we assessed different segmentation methods, that are, level set and gray level contour techniques.