Incorporative mixing in microreactors: Influence on reactions and importance of inlet designation
Shusaku Asano, Taisuke Maki, Shogo Inoue, Sumito Sogo, Masashi Furuta, Satoshi Watanabe, Yosuke Muranaka, Shinji Kudo, Jun‐ichiro Hayashi, Kazuhiro Mae
Abstract
Fast mixing is an essential feature of a microreactor. This study reveals the critical role of microscopic fluid incorporation on fast chemical reactions in a microreactor. The vortices in a microreactor produce tiny fluid segments, and the incorporation of these segments into the surrounding fluid triggers chemical reactions. The selectivity of chemical reactions highly depends on the type of the fluid segment incorporated into the fluid. Microreactor operations that consider incorporative mixing can achieve better reaction results, even with slow mixing. For example, a tee mixer showed better reaction performance with the vertical confluence configuration than with the symmetric configuration, although the symmetric 180-degree confluence provides more intense mixing. Computational fluid dynamics (CFD) simulations showed that vertical confluence enabled the division and incorporation of a stream from the horizontal inlet into another stream. The appropriate inlet designation is vital when two inlets of a microreactor differ in dimensions, directions, or positions because the different inlets provide different mixing profiles. The two inlets of the microreactor were distinguishable even though the fabrication error was insignificant. For instance, feed orientations changed the side-product yield seven times in a 3D-printed microreactor. Moreover, the impact of incorporative mixing on particle synthesis was confirmed. Switching the two inlets significantly influenced the morphology and size of the synthesized particles by changing the initial nucleation environment. In conclusion, considering incorporative mixing and optimal inlet orientation will enhance the performance and flexibility of microreaction technology.