Effect of fluid viscosities on the liquid-liquid slug flow and pressure drop in a rectangular microreactor

The hydrodynamics of liquid-liquid slug flow with various fluid systems were investigated, aiming at revealing the viscous effects of both phases. The operation range, droplet formation, film thickness and pressure drop of slug flow were studied and discussed. The results reveal the importance of inertia and viscous forces of both phases in the transition of flow patterns. Accordingly, a universal flow map based on composite terms of CacRec0.5 and CadRed0.5 was adopted, which worked well for a wide viscosity range. For droplet formation in the present system, both the squeezing and shearing regimes deviated from the classical ideal models. Under higher capillary number, the film was accumulated at the corners and lateral planes, leading to distinct droplet shapes from literature. For the two-phase pressure drop, new empirical correlations were proposed to describe the recirculation inside both the droplets and slugs. The findings can provide better guidance for optimized reactor design. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The hydrodynamics of liquid-liquid slug flow with various fluid systems were investigated to reveal the viscous effects of both phases. The study discussed the operation range, droplet formation, film thickness, and pressure drop of slug flow. Results showed the importance of inertia and viscous forces in flow pattern transition, leading to the adoption of a universal flow map and new empirical correlations for droplet formation and pressure drop.