Hydrodynamics of gas–liquid microfluidics: A review

Gas-liquid multiphase process occupies a significant part in the chemical industry, and the emerging gas–liquid microfluidic technology provides a highly efficient and controllable tool for gas–liquid systems such as chemical product synthesis, gas separation, and environmental protection. To point out the microscale gas–liquid multiphase process from the fundamental study to its utilization, this review mainly focuses on advances in the hydrodynamics of the gas–liquid microdispersion and microflow for the design of the gas–liquid microfluidic device. The progress of the gas–liquid flow pattern is first introduced, and then the microdispersion in both single-channel and multi-channel are summarized from the bubble size prediction model and operating conditions. Besides, the microflow characteristic of bubble movement velocity and pressure drop in a single-channel and flow distribution in multi-channels for scaling-up are presented, and the design procedure of gas–liquid microreactors is proposed. Finally, a summary and perspective are provided.