Co-current horizontal flow of a Newtonian and a non-Newtonian fluid in a microchannel

Abstract

In this work, the flow of two immiscible liquids in a glass microchannel, I.D.= 580μm, was exper-imentally investigated. Various aqueous glycerol solutions containing xanthan gum were the non-Newtonian fluids, while kerosene was the Newtonian one. The flow rate of the non-Newtonian fluids varied from 50 to 200μL/min, while the kerosene flow rate was kept constant. The two fluids were put in contact at a T-junction. Visual observations were made using a high speed CCD camera and data were collected by processing the corresponding video images. The flow pattern was slug flow irrespective of the fluid that initially filled the microchannel. The experimental results revealed that the length of the kerosene slugs decreases by increasing either the aqueous phase flow rate or its viscosity. Furthermore the non-Newtonian fluid results in smaller and more frequent slugs than the corresponding Newtonian one. Thus by rendering a fluid non-Newtonian the interfacial area increases and consequently the mass transport performance is enhanced. This observation is expected to aid to the optimal design of two-phase microreactors. More work is certainly needed to investigate the effect of all the design parameters on the characteristics of this kind of flow in microchannels.