Perpendicular flow is used to induce oil droplet breakup by using a capillary as water phase flow channel. It is a new route to produce monodisperse emulsions. The wetting properties of the fluids on the walls are exceedingly important parameters. Depending on the oil and water flow rates, different spatial distributions of the two phases as laminar, plugs, cobbles and drops, are obtained. The effects of two-phase flow rates on plugs and drop size are studied, and the different droplet formation mechanisms of plug flow and drop flow are discussed. Two quantitative equations utilized to predict the droplet size are developed.

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CO2/Ca(OH)2 precipitation reaction was used to prepare CaCO3 nanoparticles in this work. As a fast reaction system, nice mixing and a fast mass transfer rate of CO2 are required to enhance supersaturation. To increase the mixing performance, a microstructure reactor, a membrane dispersion minireactor, which has microfiltration membranes as the dispersion media, was introduced and CaCO3 nanoparticles with average diameters ranging from 34.3 to 110 nm were prepared. Several operating conditions were investigated for the purpose of controlling the particle size. In addition, a deep analysis on the mass transfer flux density of CO2 was carried out and the particle size decreased with the increasing of the mass transfer flux density during the reaction. Compared with a membrane-free reactor, it was found that the mixing performance was significantly enhanced by the effect of the micropore membrane, and nanoparticles cannot be prepared without it.