Gas‐Liquid Flow Patterns in a Rectangular Milli‐Structured Channel with Static Mixing Elements

Abstract

The gas-liquid flow behavior through a milli-scaled channel provided with a staggered herringbone-like static mixer was investigated using high-speed recordings. For three different substance systems consisting of water, 5 wt % acetic acid in aqueous solution, and propylene glycol as liquid phase and nitrogen as gas phase, flow patterns and their transitions were determined by analyzing image sequences of the flow and summarized in flow pattern maps. Surge flow, slug flow, and bubbly flow were observed at different flow rates. The flow distribution and transitions between flow patterns mainly depend on the viscosity and surface tension of the liquid phase. By just reducing the surface tension, slug flow is not observed, and thus an early transition into a bubbly flow regime takes place. An increase in viscosity counteracts this effect.

Influence of Liquid Properties and Design Parameters on Mass Transfer in Gas–Liquid Flow through a Miniaturized Reactor

“…In three-layer systems, two layers are oriented in one direction, and one layer is oriented in the other direction (cf. Figure b), which leads to a deflection of the gas phase toward the channel side where two of the three layers are directed to . In two-layer systems, due to the axial symmetry, the gas phase shows a more homogeneous transversal distribution compared to the three-layer system as demonstrated in Figure , which is expected to reduce transversal concentration gradients of oxygen in the liquid phase.…”

“…Painmanakul et al investigated bubble generation phenomena and have confirmed that in liquids with lower surface tensions, the interfacial area is higher. As shown in Figure , which presents a flow pattern study of Denker et al, this can be also assumed in Miprowa reactors. They have also investigated different liquid media.…”

“…This leads to a higher interfacial area and thus to higher mass transport rates. Further, bubbly flow might be the leading flow pattern in EtOH, and slug flow might be the leading flow pattern in water …”

“…Figure 2b), which leads to a deflection of the gas phase toward the channel side where two of the three layers are directed to. 29 In two-layer systems, due to the axial symmetry, the gas phase shows a more homogeneous transversal distribution compared to the three-layer system as demon- In Figure 12, it is also shown that the use of two-layer systems instead of three-layer systems reduces the expended power consumption and thus is more efficient. These results lead to the recommendation that two-layer systems should be used in water-like substance systems to increase the mass transfer performance and decrease operating costs.…”

“…Further, bubbly flow might be the leading flow pattern in EtOH, and slug flow might be the leading flow pattern in water. 29 3.2.1. Empirical Correlations.…”