Abstract: Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min^?1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d₃₂) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d₃₂ of 25–63?μm at a liquid flow rate of 1025 L·h^?1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d₃₂, and the predicted d₃₂ was in good agreement with the experimental data with a deviation within?±?15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

Key words: Ultra-high speed rotating packed bed, Microdroplet, Controllable preparation, High throughput

摘要： Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min^?1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d₃₂) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d₃₂ of 25–63?μm at a liquid flow rate of 1025 L·h^?1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d₃₂, and the predicted d₃₂ was in good agreement with the experimental data with a deviation within?±?15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

关键词: Ultra-high speed rotating packed bed, Microdroplet, Controllable preparation, High throughput