Investigation of multi-inlet arrangement effect on mesoscale bubble dynamics in the gas-liquid-solid reactor via VOF-DEM

Multi-channel gas-liquid-solid systems have attracted considerable attention across chemical, energy, and biochemical industries due to their potential applications, yet the intricate interplay between different scales of interphase interactions remains complex. This study employs the volume of fluid method coupled with the discrete element method (VOF-DEM) to investigate the multi-scale flow hydrodynamics within gas-liquid-solid systems featuring various inlet arrangements. Following thorough validation of the numerical methodology, the intricate interphase interactions, bubble dynamics, and the influence of multi-channel configurations are examined. The findings elucidate that the presence of a densely packed particle bed fundamentally alters the bubble generation process, inhibiting lateral expansion while promoting vertical growth. Consequently, this phenomenon increases the likelihood of collision and coalescence between adjacent rising bubbles. Additionally, higher Reynolds and Weber numbers facilitate vortex shedding and create open unsteady wakes, thereby enhancing mixing effects within the system. Consequently, it is advisable to adjust both the inlet size and gas flow rate to achieve Reynolds numbers exceeding 3000 and Weber numbers surpassing 10. Moreover, reactor design considerations must include proper channel spacing to mitigate the formation of large merged bubbles, which may enhance local stirring but impede global mixing. Optimizing the spacing between gas inlets enhances lateral bubble extrusion by particles, fosters a meandering ascent for bubbles, and boosts both gas-liquid contact area and gas hold-up. The insights obtained from this study provide valuable contributions to understanding the multi-channel flow behaviors in gas-liquid-solid systems and offer practical guidance for the design and optimization of such reactors.