Bubble evolution and gas-liquid mixing mechanism in a static-mixer-based plug-flow reactor: A numerical analysis

Abstract

Effective gas-liquid mixing is critical for the successful implementation of ozonation and advanced ozone-based oxidation technologies. This study focuses on a static-mixer-based plug-flow reactor derived from the HiPOxTM reactor system, which is divided into three parts. The investigation delves into the bubble evolution and gas-liquid mixing mechanism through Computational Fluid Dynamics simulations. A comparative analysis of the gas-liquid flow fields, with and without the static mixer, reveals that the mixing element primarily enhances the mixing rather than the gas dispersion. Furthermore, the study employs relative standard deviation (RSD) and bubble diameter to assess the degree of the gas-liquid mixing. The results indicate that the plug-flow reactor equipped with six mixing elements achieves the optimal mixing performance (RSD 0.793 and bubble diameter 1.384 mm) with the lowest energy consumption. Compared with the reactor with four elements, the RSD decreases by 25.7 % and the bubble diameter decreases by 23.0 %. Additionally, the energy consumption is 37.6 % lower than that of the reactor with eight elements. This investigation serves as a foundation for the application of static mixers in gas-liquid mixing and provides a basis for further research in this area.