Experimental and computational investigation of fluid flow and solid transport in split-and-recombine oscillatory flow reactors for organic chemistry in water

This study analyzes fluid dynamics and solid transport in split-and-recombine oscillatory flow reactors, to improve the understanding of the mechanisms behind the resuspension capacity of solids in flow driven by their efficacy in multiphase reactions. Based on its importance as a sustainable reaction medium, H2O was utilized as liquid phase. Experiments in the HANU 2X 5 flow reactor reveal a six-fold reduction in particle deposition under oscillatory flow with SiO2 slurries compared to constant flow. A DoE approach investigated the influence of oscillation parameters and flow rate, revealing the importance of tuning parameters to achieve homogeneous suspension. Quantitative transport up to 10 wt% SiO2 slurries was achieved. A computational fluid dynamics model revealed the presence of large recirculation and positive upward velocities near the static mixers under oscillatory flow, which facilitate particle resuspension, up to five times compared to stationary flow. Strategic asymmetries within the reactor enhance resuspension. Lagrangian particle tracing was implemented through an original procedure, allowing reduced computational time by 82%. The simulation validated the benefits of oscillations in sustaining particle suspension, explaining the mechanism that prevents deposition at the reactor bottom. The combination of experimental and computational approaches provides valuable insights for optimizing oscillatory flow reactor design.