CFD–PBM Numerical Study on Liquid–Liquid Dispersion in the Q‑Type Static Mixer

Numerical simulations of silicone oil–water two-phase turbulent dispersion mixing in Q-type static mixers (QSM) are performed using computational fluid dynamics (CFD) coupled with a population balance model in the range of Re = 8000–24 000. The numerical prediction of Sauter mean diameter (d₃₂) in the Kenics static mixer had a good agreement with experimental results. The centerlines of droplet size distributions gradually shift to the left, and the flat profiles with lower peak values become much thinner with higher peak values with increasing axial length. The dimensionless d₃₂ decreases with increasing element number and Re and stabilizes below 0.03 at the axial length z/l > 10. A correlation among d₃₂, We, and residence time is obtained to predict the equilibrium characteristics of droplet groups. The average shear rate in the QSM with right–left staggered segments (RL-90-QSM) is 1.15–2.41 times that with right–right staggered segments, which indicates that RL-90-QSM has excellent droplet breakage performance.