Characteristics of Bubble Dispersion under Nonuniform Electric Field in an Up-Flow Bubbling System: From Charged Bubble to Charged Bubble Cluster

Abstract

Electric dispersion is a novel and promising method for bubble dispersion. In this study, the laboratory scale bubbling reactor with a nonuniform electric field was established. A high-speed camera was used to observe and investigate the electric dispersion in a nitrogen biodiesel up-flow system. The results showed that dynamic characteristics of the bubble dispersion, including bubble volume, shape, and rising velocity, were strongly correlated with the electric field strength. The bubble could be controllably dispersed into numerous charged bubbles through electric dispersion, with the equivalent diameter decreasing from 1.88 to 0.64 mm. As a result, the charged bubble cluster was obtained with a Gaussian distribution. The number of the charged bubble cluster per cubic meter increased from 5.01 × 10⁵ to 5.40 × 10⁷, which significantly improved the gas–liquid mass transfer area. Moreover, changes in gas and liquid velocities had little effect on the charged bubble cluster. Both the size and number density of the charged bubble cluster could be regulated by adjusting the electric field strength. Additionally, a model was developed to predict the mean size of the charged bubble cluster, with an average relative error of 6.37%. Overall, the results would provide a reference for the application of electric dispersion in bubbling reactors.