Study of Micromixing in a Microreactor with Counter-Current Intensively Swirled Flows

Abstract

A comparative study of micromixing in a microreactor with counter-current intensively swirling flows (MRISF-CC) is performed for different methods of flow feed using the iodide–iodate technique. The dependence of the micromixing quality (the so-called segregation index) on the specific energy dissipation rate is found for three methods of feeding solutions to the device. In the first and second methods, the solutions are fed to the tangential and axial nozzles of the left and right chambers of the device, respectively (corresponds to the mixing conditions in the single-stage microreactor MRISF-1). In the third case, the solutions are fed to two tangential nozzles and both flows are intensively swirled and mixed in a limited volume, while the axial and circumferential velocity components are directed towards each other. In the third case, the quality of micromixing was up to ten times higher (at a given value of the specific energy dissipation rate) than in the first two cases, and up to 2400 times higher than in a device with a magnetic stirrer. Thus, the implementation of mixing of counter swirling flows provides improvement in the quality of micromixing compared to other types of microreactors with swirling flows. The effect of reducing the exponent to ≈2.2 in the formula relating the specific energy dissipation rate to the total flow rate of solutions has been found, which can be explained by the mutual damping of the angular momentum during the interaction of two vortices. The obtained results make it possible to explain the influence of the micromixing conditions on the synthesis of nanosized particles from solutions.