Experimental investigation on the performance of drag reducing polymers through two pipe diameters in horizontal oil-water flows

In this paper, experiments were conducted to understand the influence of a small change of pipe diameter in the effectiveness of drag reducing polymer (DRP) in horizontal oil-water flow. Two pipe diameters were used in this study; 19 and 25.4. mm pipes. The results showed a remarkable influence of pipe diameter on the polymer efficiency in modifying flow patterns and drag reduction. The results from both pipes showed that only 10. ppm polymer concentration is needed to achieve the maximum drag reduction for each investigated condition. The presence of DRP extended the region of stratified and dual continuous flows. However, the percentage increase in the stratified region is more significant in the 25.4-mm pipe while the extent of the dual continuous pattern in the 19-mm pipe is larger than that in the 25.4-mm pipe. Regardless of the pipe diameter, annular flow changed for all the investigated conditions to dual continuous flow. The dispersed region (water continuous or oil continuous) decreased after introducing DRP but the decrease is larger for the 19-mm pipe especially for dispersion of oil in water. The results for both pipes revealed that the maximum drag reduction is achieved when the flow is dispersed oil in water; however, higher drag reduction was obtained in the larger pipe diameter. Drag reductions up to 60% were observed in the 25.4-mm pipe in comparison with up to 45% achieved in the 19-mm pipe.