Two-phase flow and mass transfer in microchannels: A review from local mechanism to global models.

• The hydrodynamics, mixing and mass transfer of two-phase processes are reviewed. • Bubble/droplet formation mechanism and scaling models are summarized. • The dynamic behavior during formation stage is highlighted. • The circulation topology and mixing inside both droplets and slugs are discussed. • The interfacial mass transfer regimes and simulative models are presented. Microreaction technology is preferential in process intensification and chemical synthesis, especially in multiphase applications. A thorough understanding of the hydrodynamics and mass transfer is the pre-requisite for implementing such applications. This review discusses the recent progress on the flow and mass transfer of two-phase systems in microchannels, in a multi-scale view from local mechanism to global behavior. The flow patterns, the formation of bubbles/droplets, and the manipulation of bubbles/droplets are presented and discussed in detail. The mass transfer aspects include the velocity profile and mixing inside droplets/slugs, as well as the interfacial mass transfer mechanism and simulative models. The aim of the review is to show directly the physical ingredients which determine the transport phenomena, help explain the observed behavior, and guide reactor design. To simplify the physical ingredients, the attention is focused on straight channels while phenomena in other channels (e.g. , meandering channel) are neglected. [ABSTRACT FROM AUTHOR]