Effect of pipe diameter on horizontal oil-water flow before and after addition of drag-reducing polymer part II: Holdup and slip ratio

In this experimental work, the effect of the drag-reducing polymer on the holdup and slip ratio of the oil-water flow in three different horizontal acrylic pipes was investigated. The internal diameters (IDs) of the pipes were 30.6-mm, 55.7-mm and 74.7-mm. The flow conditions of the oil-water flow consisted of 0.4–1.6 m/s mixture velocities and 0.1–0.9 input oil volume fractions. The master solution of the polymer (commercially known as AN 105-SH) was prepared at 2000 ppm concentration and injected into the water phase at controlled flow rates to provide 40 ppm concentration in the phase. The measurement of the holdup was carried out with help of quick closing valves after which the slip ratio was determined. The results showed that the water holdup and by extension, the slip ratio before the addition of the DRP increased with increase in the input oil volume fraction at low mixture velocity while the reverse was the case at high mixture velocity. The addition of the DRP increased the water holdup and the slip ratio only in water-dominated flow regions in all the three pipes. Finally, the increase in the pipe diameter also increased the water holdup and the slip ratio before and after the addition of the DRP in most of the flow conditions.