Enhancement of gas-liquid mass transfer and mixing in zigzag microreactor under ultrasonic oscillation

Ultrasonic oscillation can be leveraged to efficiently intensify the gas-liquid mass transfer in microreactors. This work aims at revealing the gas-liquid mass transfer enhancement mechanism in zigzag ultrasonic microreactors (zigzag USMRs). A rigorous and quantitative comparison of the O-2 mass transfer performance and mixing efficiency inside the liquid slug during the Taylor bubbles flowing within the straight and zigzag USMRs was made. The synergetic effect of zigzag geometry and ultrasonic oscillation can enhance the mass transfer by an enhancement factor from 1.88 to 3.80. However, this synergetic effect would not have a significant impact on the mixing efficiency inside the liquid slug with an enhancement factor from 0.91 to 1.03. The synergetic enhancement effect of gas-liquid mass transfer performances could not be regarded as simply adding up the separate contribution of zigzag geometry and ultrasonic oscillation. Semi-empirical equations were established to predict the overall mass transfer coefficient in zigzag USMRs. (C) 2021 Elsevier Ltd. All rights reserved.