Hydrodynamics and Scaling Laws of Gas–Liquid Taylor Flow in Viscous Liquids in a Microchannel

Abstract

The hydrodynamics of gas–liquid Taylor flow in microchannels is vital to the microreactor’s application, but its characteristics in viscous liquids are rarely reported. Accordingly, this study concentrates on the characteristics of bubble behavior in viscous liquids (45.6–240.5 mPa·s). The results show that the viscosity effect could dominate the bubble morphology. Importantly, considering the liquid film distribution, a novel parameter as the equivalent liquid film thickness is proposed for the square microchannel and it is strongly related to the capillary number and gas–liquid flow rate ratio. Besides, the bubble velocity first decreases to a minimum value and then becomes faster with the flow rate of the liquid, and the ideality of the multiphase system decreases with the increase of liquid viscosity and pressure drop. Finally, the viscosity term is introduced to the pressure drop equation based on the Lockhart–Martinelli type. This work enriches the understanding of the viscosity effect on gas–liquid microflows.