A study of two-phase flow in monoliths using ultrafast single-slice X-ray computed tomography

• Ultrafast single-slice X-ray computed tomography has been applied.
• Cross-sectional liquid holdup inside the monolith has been visualized and quantified.
• Gas-liquid maldistributions have been evaluated for different feeding conditions.
• Longitudinal sectional liquid holdup distributions have been calculated.
• Characteristic spatial and temporal holdup pattern inside the monolith channels patterns could be identified and, associated with the flow regime.
• The in-channel flooding and draining behavior has been investigated.

Running chemical reactions in monolithic structures is being considered as highly promising for intensifying industrial reaction processes. A potential pitfall of such structures is the difficulty to achieve homogeneous and well defined gas/liquid distributions patterns with economically feasible distribution mechanisms. Experimental studies on gas/liquid distribution in monoliths are often hampered by missing measurement and visualization techniques to disclose the two-phase flow inside the narrow and opaque channels.This paper presents results of a study carried out with ultrafast single-slice X-ray tomography, a novel imaging technique, which can overcome these limitations. We investigated two-phase flow in two different types of square-channel monolith structures, one with high cell density of 400 cpsi and one with low cell density of 39 cpsi. Our study discloses in-channel flooding and draining behavior via extraction of characteristic distribution parameters, such as averaged and channel-linked liquid holdup, two-phase flow patterns and liquid maldistribution from X-ray images using advanced image processing techniques.