Thesis (M.Eng.)--Chulalongkorn University, 2009

To present a laboratory experiment of drag reduction in coiled tubes with various concentrations of polymer additives and curvature ratios. Three different curvature ratios i.e. 0.012, 0.018, and 0.024, are studied. The employed polymer additives are Polyacrylamide, Polyvinyl Alcohol, Anionic Polyacrylamide, and Cationic Polyacrylamide. For each additive, six concentrations of polymer solution of 0.01, 0.03, 0.05, 0.07, 0.10, and 0.15% by volume are studied. The best concentration is determined from the drag reduction exhibited by the fluid. In addition, computational simulation by a commercial software (FLUENT), is used to investigate the drag reduction behavior. Of these techniques, the emphasis is on the laboratory experiment while the simulation is used to verify and compare the experimental results. The results showed that, in the laboratory experiment, small amounts of polymer additive could reduce the solvent friction pressure substantially. Highest friction pressure decrease is 60% at the concentration of 0.07% by volume with Anionic Polyacrylamide additive. The empirical correlations indicate excellent agreement between the experimental data and existing predicting trends. For the numerical simulation, the results showed simulation trends which conformed to the experimental measurements. However, the numerical simulation and the simulation with power fluid model illustrated only 2-7% drag reduction which indicated that the turbulence and non-Newtonian fluid model in the commercial software were not suitable for studying the drag reduction in coiled tubes