The addition of drag-reducing agents to reduce spiral pipe friction loss has attracted attention as a method to conserve energy. In addition to reducing drag, these agents are required to have a low environmental load and conserve natural resources. Therefore, naturally occurring natural cellulose additives, which are considered to have a low environmental load, have recently received much attention. In spiral pipe twisted with a constant pitch in relation to the axis a swirling flow occurs when fluids flow in the pipe. The practical application the spiral pipe presents a very useful method for preventing the sedimentation phenomenon in a transport pipeline for the hydraulic transport. Here we focused on Nata de coco, a type of biopolymer that exhibits low mechanical degradation, and found that it reduced drag by up to 22% at a concentration of 100 ppm with error ± 2 %. With respect to the drag reduction (DR) mechanism, we investigated the relation between DR phenomena and the degradation of Nata de coco by measuring the pressure drop. From the pressure drop and volumetric measurement, shear stress and shear strain were calculated, and characteristic of Nata de coco flow was examined. Spiral pipe with was larger ratio of pitch and diameter (p/D) gives significant effect to reduce friction, and increase drag reduction. The effect of Nata de coco was delayed the transition regime. DR increased as the size of the network of Nata de coco increased.
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.