Effect of Viscosity on Liquid–Liquid Slug Flow in a Step T-Junction Microchannel
Li Ma, Zifei Yan, Chencan Du, Jian Deng, Guangsheng Luo
Abstract
The multi-phase microflow hydrodynamics plays a significant role in the design of microreactors. The effects of two-phase viscosity on the hydrodynamics of liquid–liquid slug flow in a step T-junction microchannel was investigated systematically in this work. The paraffin oil and chitosan aqueous solution with different viscosities were used as the continuous and dispersed phase, respectively. The effects of various conditions on droplet size, droplet moving velocity, liquid film thickness, and pressure drop in the microchannel were studied and discussed. The results reveal that both dispersed and continuous phase viscosities have critical effects on the flow characteristics. Liquid film thickness, droplet velocity, and pressure drop are deviated from the conventional ideal model. Accordingly, two new semi-empirical models were established for calculating droplet velocity and liquid film thickness. The droplet velocity and liquid film thickness could be predicted by udropletumix=11−1.54Cac0.51 and δD=0.40Cac0.51, respectively. For the pressure drop, a modified model was developed by considering the real velocity of two phases, the geometric structures of microchannel, and physical properties. The predicted values by the modified model are in good agreement with experimental results, and the modified model has shown its good universality. This work could provide a more reliable guidance for the design of liquid–liquid microreactors.