Two-phase flow hydrodynamic study in micro-packed beds – Effect of bed geometry and particle size

• Bed geometry (circular or square) does not affect the flow regime transition point.
• Wetting pattern hysteresis decreases with a decrease in particle size.
• Micro-packed beds transient time decreases with increase in particle size.
• Micro-packed beds of square geometry have shorter transient time than circular ones.

Microscopic visualizations nearby the wall region of micro-fixed beds and hydrodynamic measurements during gas–liquid two-phase flows were carried out with an aim to investigate the effect of particle size and capillary tube shape on the bed pressure drop, flow regime transition, hysteresis and bed transient response to flow-rate step perturbations. Visualizations through inverted microscopy revealed that a decrease in particle size leads to early inception of a high interaction flow regime whereas changing capillary shape from circular to square had no effect on flow regime changeover. The effect of particle size on the wetting pattern hysteresis in square micro-packed beds was also investigated in both imbibition and drainage paths. It was found that wetting pattern hysteresis decreases with a decrease in particle size. Finally, the transient behavior of micro-fixed beds of circular and square geometries packed with particles of two different sizes were studied by monitoring the bed pressure drop variations upon step changes in liquid flow rate at iso-G conditions. Larger particle sizes and square geometry showed shorter transient times as compared to smaller particle sizes and circular geometry.

Effect of decreasing particle size (increasing D/dp ratio) on wetting pattern hysteresis at the same gas and liquid superficial velocities (UGS = 25.5 cm/s, ULS = 1.1 mm/s).Figure optionsDownload as PowerPoint slide