Vibrating a bubble column reactor can increase the gas holdup (void fraction), as well the mass-transfer rate. Since the seminal work in the 1960s, there has been minimal effort focused on this topic until the early 2000s. Currently there are several groups studying this problem making advancements in our fundamental understanding of the process with detailed experiments, theoretical analyses, and physics-based models. However, throughout the literature, there are inconsistencies with both experimental results and proposed scaling of the fundamental properties, as well as minimal data spanning the parameter space. This review serves as an overview of key works from the 1960s and the 2000s, as well as to identify these inconsistencies between key studies. Recommendations for how to proceed with future work is provided with an emphasis on defining the parameter space in terms of the Reynolds number and the Froude number.

No abstract

Abstract:Vertical vibration is known to cause bubble breakup, clustering and retardation in gas-liquid systems. In a bubble column, vibration increases the mass transfer ratio by increasing the residence time and phase interfacial area through introducing kinetic buoyancy force (Bjerknes effect) and bubble breakup. Previous studies have explored the effect of vibration frequency (f ), but minimal effort has focused on the effect of amplitude (A) on mass transfer intensification. Thus, the current work experimentally examines bubble size, void fraction, and mass transfer in a bubble column under relatively high amplitude vibration (1.5 mm < A <9.5 mm) over a frequency range of 7.5-22.5 Hz.Results of the present work were compared with past studies. The maximum stable bubble size under vibration was scaled using Hinze theory for breakage. Results of this work indicate that vibration frequency exhibits local maxima in both mass transfer and void fraction. Moreover, an optimum amplitude that is independent of vibration frequency was found for mass transfer enhancements. Finally, this work suggests physics-based models to predict void fraction and mass transfer in a vibrating bubble column.