Experimental study of ensemble phase splitting features of water-oil slug/droplet flow at a branching micro-T-junction

This paper reports the ensemble phase splitting features of water-oil slug/droplet flow at a micro-T-junction with three equal branches. The hydraulic diameter of the channels is around 850 mu m. The slug flow shows almost no phase separation (even splitting) at various splitting ratios of continuous flow, which agrees with the prediction of a traditional mechanism. Despite that the morphology of the studied droplet flow apparently looks like slug flow, the phase splitting features of them are distinctively different. At certain conditions, the separation degree of water and oil of droplet flow reaches as high as 45 %. The "abnormal" uneven phase splitting features are resulted from the transition of splitting mode of dispersed phase from pressure dominant process to shear dominant process. The high phase separation degree can be achieved by increasing Capillary (Ca) number of the continuous flow to a critical value larger than 0.02 and increasing the splitting ratios of continuous flow slightly larger than 0.5. The mechanism is discussed to understand these "abnormal" splitting features of droplet chains at high Ca number. (c) 2023 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.