Phase hold-up, axial dispersion, droplet size, and distribution of liquid–liquid flow in micropacked bed reactors

Hydrodynamic characteristics in micropacked bed reactors (μPBRs) are of great significance for the in-depth understanding of mass transfer and reaction in liquid–liquid flow. Herein, the phase holdup (h), axial dispersion coefficient (D_L), droplet size (D_ave), and distribution of the organic phase in the liquid–liquid system of μPBRs are studied via residence time distribution and visualization experiments. The effects of flow rate, phase ratio, packing and reactor size, and solution viscosity on hydrodynamic characteristics of μPBRs are investigated. The ranges of h, D_L, and D_ave are 0.18–0.87, 3.42 × 10⁻⁹–8.57 × 10⁻⁷ m²/s, and 22.2–319.8 μm, respectively. The droplet sizes follow a Rosin–Rammler distribution, and the width of the droplet size distribution is discussed. The specific surface area of μPBRs reaches 1073 cm²/cm³, which is two orders of magnitude larger than traditional reactors. In addition, empirical correlations for h and dimensionless D_ave are established and predict the experimental results, and the errors are within ±20% and ±25%.