Numerical simulation of two-phase separation in T-junction with experimental validation

Abstract

Liquid carryover in T-junction due to splitting nature of two-phase flow causes serious issues for downstream equipment which is not designed to handle excessive liquid. In this paper, the phenomena of liquid carryover in T-junctions were analyzed using the Volume of Fraction (VOF) together with the k-ε turbulence model. T-junction separation efficiency was measured through mass flow rate fraction of air and water between the branch and main arm over a range of diameter ratios 0.6 to 1.0, water superficial velocity 0.186 to 0.558 m/s and air superficial velocity 4 to 8 m/s. The results showed simulation model was successfully validated with average deviation of less than 5% and can be used to predict phase split of slug flow in T-junction. The numerical model confirmed the significant influence of diameter ratio and superficial velocities of air and water on phase split. Reduced T-junction delivers better separation performance compared to regular T-junction. In slug flow regime, T-junction’s performance can be improved by either decreasing air velocity or increasing water velocity. A new dimensionless parameter, namely the area under the curve of separation efficiency (S), was proposed and proved as a qualified judging criteria for evaluating phase separation efficiency of T-junctions.

Effect of airfoil distance to water surface on static stall

“…If the volume of flow is F = 0, the cell is filled with air and if F = 1, the cell is filled with water. Also, cells with values of 0 < F <1 are cells that contain some water and some air (F is mass flux) [17][18][19][20].…”

Experimental investigation of multiphase separation in different flow regimes through T-junction with an expander section

“…However, as the pressure in the run arm increases, the liquid is carried over into the branch arm along with the gas phase. As the downstream equipment was not compatible to handle excessive liquid, therefore, it causes the breakdown of downstream, resulting in frequent and unpredicted maintenance cost of the equipment [2][3][4]. Efforts have been made to increase the separation efficiency of a T-junction to make it applicable as a phase separator, for offshore and subsea application where space is limited for large conventional separators [5,6].…”