Gas/liquid/liquid three-phase flow patterns and bubble/droplet size laws in a double T-junction microchannel

Dynamics and controllability of droplet fusion under gas-liquid-liquid three-phase flow in a microfluidic reactor

Gas–liquid–liquid three-phase flow systems have unique advantages of controlling reagent manipulation and improving reaction performance. However, there remains a lack of insight into the dynamics and controllability of water droplet fusion assisted by gas bubbles, particularly scaling laws for use in the design and operation of complex multiphase flow processes. In the present work, a microfluidic reactor with three T-junctions was employed to sequentially generate gas bubbles and then fuse two dispersed water droplets. The formation of the dispersed phase was divided into multiple stages, and the bubble/droplet size was correlated with operating parameters. The formation of the second dispersed droplet at the third T-junction was accompanied by the fusion of the two dispersed water droplets that were formed. It revealed a two-stage process (i.e. drainage and fusion) for the two droplets to fuse while becoming mature by breaking-up with the secondary water supply stream. In addition, a droplet contact model was employed to understand the influence on the process stability and uniformity of the merged/fused droplets by varying the surfactant concentration (in oil), the viscosity of the water phase, and the flow rates of different fluids. The study provides a deeper understanding of the droplet fusion characteristics on gas–liquid–liquid three-phase flow in microreactors for a wide range of applications.

Gas–liquid–liquid three-phase flow systems have unique advantages of controlling reagent manipulation and improving reaction performance.

Manipulation of gas-liquid-liquid systems in continuous flow microreactors for efficient reaction processes

Gas-liquid-liquid flow in microreactors holds great potential towards process intensification of operation in multiphase systems, particularly by a precise control over the three-phase contact patterns and the associated mass transfer enhancement. This work reviews the manipulation of gas-liquid-liquid three-phase flow in microreactors for carrying out efficient reaction processes, including gas-liquid-liquid reactions with catalysts residing in either liquid phase, coupling of a gas-liquid reaction with the liquid-liquid extraction, inert gas assisted liquid-liquid reactions and particle synthesis under three-phase flow. Microreactors are shown to be able to provide well-defined flow patterns and enhanced gas-liquid/liquid-liquid mass transfer rates towards the optimized system performance. The interplay between hydrodynamics and mass transfer, as well as its influence on the overall microreactor system performance is discussed. Meanwhile, future perspectives regarding the scale-up of gas-liquid-liquid microreactors in order to meet the industrial needs and their potential applications especially in biobased chemicals and fuels synthesis are further addressed.