Hydrodynamics and mass transfer performance of gas–liquid two-phase flow in a high-throughput chaotic microreactor

Microbubbles have been widely applied in various fields. Here, an oscillating feedback microreactor (OFM) was designed to produce microbubbles at high throughput (5–80 mL/min), where the hydrodynamics and mass transfer performance of gas–liquid two-phase system were investigated. The hydrodynamics results showed that three secondary flows (oscillation, vortex, and feedback) could be effectively generated for inducing chaotic flow in the OFM, and the gas phase could be effectively broken up into small microbubbles. The bubble size was more sensitive to the liquid phase flow rate than the gas phase. Two dimensionless prediction formulas for bubble Sauter size were proposed based on gas–liquid flow ratio and Reynolds number at different liquid flow rates. The mass transfer experiments showed that the volumetric average mass transfer coefficient k_La was 1–3 orders of magnitude higher than those of conventional reactors.