Droplet flux measurements in two-phase, low liquid loading, horizontal pipe flow using a high-density gas

Entrained fraction is one of the essential parameters needed for the prediction of frictional pressure drop and efficient design of downstream facilities. In the literature, there are very few entrained fraction datasets focused on low liquid loading flows, and even less datasets obtained from high pressure systems. This paper provides experimental entrained fraction data for low liquid loading gas-oil flows in a 100-mm diameter horizontal PVC and carbon steel pipe. High-density sulphur hexafluoride (SF6) gas and Exxsol D60 oil are used as the fluid phases to mimic actual field conditions. Superficial gas and oil velocities are varied between 5 m/s to 15 m/s and 1 mm/s to 7 mm/s, respectively. Local drop flux along the vertical diameter of the pipe cross-section is measured using the isokinetic sampling approach. Effects of several parameters such as system pressure (gas density), gas and liquid flow rates, and pipe material on the entrained fraction are studied. As expected, the entrained fraction increases with either the gas density or the gas velocity. The effect of liquid flow rate on the entrainment is not obvious; results show either a constant level or a decrease in entrainment with an increase in liquid flow rate, depending on the gas flow rate. The measurements conducted using two different pipe materials (PVC and carbon steel) demonstrated that surface material can cause significant differences in the entrainment. Therefore, the near-wall film behavior will have considerable influence on the entrainment mechanism, especially when the thickness of the liquid film becomes very thin. Finally, this paper also provides an evaluation of the existing correlations and/or models available in the literature against the acquired entrainment data using the high-density gas test facility.