EFFECT OF COMBINED ADDITIVES ON DEGRADATION RESISTANCE OF DILUTE POLYMER SOLUTIONS UNDER TURBULENT FLOW

إنجليزية
number: 
2634
Degree: 
Author: 
Lubna Abdul Kareem Naeem Al-Gazi
Supervisor: 
Prof. Dr. Jabir Shanshool
year: 
2011

           The experimental work was devoted to study the drag –reduction (DR) properties of various additive types, both in the single and binary mixed forms. Two polymer types, of high molecular weights 4 and 7 millions were used in the present investigation,namely, polyethylene oxide PEO as flexible synthetic polymer andAmylopectin as rigid polysaccharide from natural resources.Moreover, a certain type of natural Clay (Kaoline) and Aluminumsulfate (Alum) are included as suspended particles or in the colloidform. Sodium lauryl ether sulfate (SLES) as anionic surfactant wasalso used as additive. The drag reduction properties of the different additives were conducted in a closed loop circulation of turbulentwater  flow.The flexible polymer, PEO at concentrations range from20 to 100 ppm, was significantly high efficient drag reducing agent inturbulent water flow at 66810 Reynolds number. Otherwise, the timedependence DR showed that PEO undergo undesirable shear degradation under turbulent flow. Low concentrations enhance thedegradation rate. Alum could be considered as a good drag reducer agent. Otherwise Clay showed relatively low drag reduction ability.The drag reduction effectiveness of Clay as well as Alum additives isapparentable unchanged by shear re – circulation turbulent flow, up to 15 hours considered time. These may be to the stability of rod – likemicelles in the suspended or colloid forms respectively. Both SLESsurfactant and Amylopectin rigid polymer showed moderate dragreduction effectiveness in turbulent water flow about 13.5% at  200ppm concentration and 6.0 m3 /h flow ate.Moreover, Amylopectin was likely shear degradable, almost the same type of behavior wasobserved for Amylopectin as in the case of PEO. The time dependence drag reduction with SLES additive explained an extraordinarybehavior. The SLES surfactant with rod – like micelles remainrelatively stable for certain time of turbulent recirculation according to the SLES concentration, after that the %DR decreases until minimumvalues were reached. Furthermore, micelles could be reformed during the stopping period leading to maximum drag reduction to be occurred.A slight increase of drag reduction was observed by mixing Clay,Alum or Amylopectin with  polyethylene oxide as Co – additives.While SLES – PEO admixture enhanced the DR performance. All ofthe considered Co  – additives declined the susceptibility todegradation with shearing time  recirculation flow. Increasing the concentration of Co – additive leaded to reduce the rate of degradation ability of admixture as drag reducer agent. SLES and Amylopectin Co– additive were slightly more efficient to decline the degradationability.The time dependence degradation behavior of the three solutions containing PEO + Clay, PEO + Alum and PEO +Amylopectin in turbulent flow was analyzed by modifying thefractional exponential decay equation DR(t)/DR(0) = exp [-(t/λ].The modified equation was found to fit the experimental data of the f)1-nf three solutions better than the original equation.   

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