Pressure drop of gas–liquid Taylor flow in square microchannels

Abstract

The pressure difference in gas–liquid Taylor flow in square microchannels with three different hydraulic diameters (190, 298, and 505 μm) were measured. Three liquids (Water and two types of glycerol-water solutions) were used as the liquid phase, and N2 gas was used as the gas phase. The experiments were carried out for the ranges of 1.98 × 10−3 < CaT < 0.132 and 2.61 < ReT < 661, where CaT and ReT are the capillary and Reynolds numbers based on the total volumetric flux, respectively. The measured pressure drop of Taylor bubbles based on the unit cell model was compared with existing models, and large discrepancies could be recognized. Dimensionless pressure drop of a Taylor bubble increased with the capillary number, and depends on the liquid viscosity and the hydraulic diameter at the same capillary number in the middle and high capillary number region, i.e., the inertia effect. Hence, a new pressure drop model including these effects as dimensionless numbers was developed based on the relationship between the pressure drop and liquid film thickness of a Taylor bubble, and it could show good agreement with the measured data. The pressure drop of Taylor flow could also be evaluated using the unit cell model with the developed model. In addition, a pressure drop model for Taylor flow based on only the total volumetric flux was developed in terms of convenience of prediction.