Experimental Study of Hydrodynamics and Mass Transfer in Microchannels for Designing Microreactors and Microextractors

The development of continious single-phase and two-phase microreactors and microextractors requires information on the hydrodynamics of the flows in such devices: velocity and vorticity distributions, mixing efficiency, and two-phase flow regimes, and their influence on the mass-transfer rate. The paper presents studies of the local hydrodynamic characteristics of flow and mass-transfer processes in T-type microchannels using optical techniques. For a single-phase microreactor, the velocity fields and concentration fields are measured. The intensification of mixing during the transition to the engulfment flow regime is shown. For two-phase microreactors with different sets of immiscible liquids, flow regimes are visualized, and a dimensionless complex for generalizing the experimental data is proposed. It is shown that neural-network algorithms trained on a large sample allow predicting flow regimes with high accuracy (up to 98%). The slug flow regime with superposition of external pressure pulsations of the dispersed phase is investigated. It is shown that the velocity field inside the plugs changes periodically, which can be used to intensify mass transfer. Using the micron-resolution laser-induced fluorescence (micro-LIF) technique, local mass transfer in a two-phase microextractor is studied.