تقليل الاعاقة في الجريان المضطرب باستخدام البولي اكريل امايد وصمغ الزانثان : دراسة عملية ونظرية == Turbulent Drag Reduction By Polyacryl Amide And Xanthan Gum, Experimental And Theoretical Investigation
Author name:
احمد عدنان عطشان
Supervisor name:
جبار شنشول جمالي
General topic:
Chemical Engineering
Specific topic:
Chemical Engineering
Degree:
Master
University:
Al-Nahrain University - College Of Engineering - Department Of Chemical Engineering
Language:
English
Full text from the source:
https://nahrainuniv.edu.iq/sites/default/files/THESIS_8.pdf
University location:
Baghdad
First pages:
38T321 - p.pdf
Abstract:
This work presents an experimental study of the drag - reduction performance of two water - soluble polymers, Polyacrylamide(PAAM) as flexible, linear synthetic polymer and Xanthan Gum(XG) as a rigid polysaccharide from natural resources. The flow loop used consisted of 0.5 O.D. inch straight pipe with a test section of 3 m length. A 0.5 inch O.D. vertical tubing with elbows was also included to compare the drag - reduction behavior between both tubing configurations. Various concentrations of polymeric additive and water flow rates were tested. The results show that the drag - reduction in vertical piping are significantly lower than in straight type for both polymer type. The dragreduction efficiency of Xanthan Gum agent is much lower than polyacrylamide. Higher concentrations of XG about 150 ppm is required to get exactable drag - reduction performance about 12.84% in the straight pipe. While about 40.3% drag - reduction was achieved with about 50 ppm Polyacrylamide with the same conditions. Moreover, the drag - reduction efficiency of XG can be improved by mixing with Polyacrylamide agent at a given conditions.Part of the experimental work was devoted to study the performance of Polyacrylamide as drag - reducing agent with the existence of small amounts of sodium chloride acts as an inhibitor to the ability of the additive, resulting in lower drag - reduction probably due to collapse of PAAM at more compact structure with the addition of sodium chloride as strong ionic salt.Polyacrylamide and Xanthan Gum additive undergo undesirable mechanical degradation with increasing of circulation time, leading to lower drag - reduction performance. The molecular degradation is likely to occur at low additive concentrations and low turbulence flow, in vertical piping, since the polymeric additives are exposed to shear stresses.Further attempt was done in present investigation to find correlations for accurately predicting drag - reduction characteristics of drag - reducing agents, used in published works. A published time scale hypothesis for prediction of drag - reduction values, the friction factor data as a function of the polymer concentration, shear stress, Reynolds number, pipe diameter. The experimental friction factor results were taken from a published work for gas oil with polyisobutylenes. Good agreement between measured and predicted friction factor. Further attempt was made to correlate the mechanical degradation ability by modifying the Kouraush, Williams and Watt (KWW) equation. The experimental data were taken from a published work for Polyethylene Oxide. The modified equation was found to fit experimental data better than the original KWW equation.
