Drag reduction in exceptionally dilute polymer solutions

Oliver, Dana; Bakhtiyarov, Sayavur I.

doi:10.1016/0377-0257(83)80008-1

Cited by 25 publications

(14 citation statements)

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“…Kulicke and collaborators 1) report that a single chain can cause DR; the domain formation in our model explains their finding. The 0.02 ppm DR reported by Oliver and Bakhtiyarov 24) and already mentioned is explained as well. As noted above, the very presence of macromolecular chains creates structures stable enough to cause DR.…”

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confidence: 81%

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Drag reduction and solvation in polymer solutions

Brostow¹,

Majumdar

Singh

1999

Macromol. Rapid Commun.

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SUMMARY: A model is described which explains drag reduction (DR) in dilute polymer solutions in terms of solvation of macromolecular chains and formation of relatively stable domains. The domains partly suppress the vortex formation, act as energy sinks, and also play a role in mechanical degradation in flow (MDF). We report ultrasonically determined solvation numbers for a series of copolymers with the same chemical structure but differing widely in their intrinsic viscosities. The solvation numbers confirm the model. Thus, we have a criterion for selection of DR agents with low MDF for: oil well operations; crude oil transport; fire fighting; high sewer throughput; irrigation; hydrotransport of solids; marine applications; and biomedical applications including the arteriosclerosis prevention.

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confidence: 81%

“…Oliver and Bakhtyarov 24) report DR in aqueous high molecular mass poly(acrylamide) solutions even at c = 0.02 ppm. The low-ppm DR results also support the model proposed in ref.…”

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confidence: 97%

Drag reduction and solvation in polymer solutions

Brostow¹,

Majumdar

Singh

1999

Macromol. Rapid Commun.

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“…For comparison, the concentration dependence of viscosity for linear, nonassociating chains is η ∼ φ 1.3 below φ e and η ∼ φ 3.9 above φ e according to de Gennes' reptation model. We note that the η ∼ φ 5 …”

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confidence: 99%

Effects of Pairwise, Self-Associating Functional Side Groups on Polymer Solubility, Solution Viscosity, and Mist Control

et al. 2009

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The extent of MPA incorporation was determined upon analysis of 1 H NMR spectra by integration of backbone and side-group peaks, with the following complication. For PB functionalization with MPA, we expect two peaks between 2.85 and 2.55 ppm corresponding to HO 2 CCH 2 CH 2 S-protons and HO 2 CCH 2 CH 2 S-, with one or more additional peaks (depending on whether cyclic structures are formed or not) around 2.55 ppm, corresponding to HO 2 CCH 2 CH 2 SCH 2 -protons. Experimental results consistentlyshowed two large, partially overlapping peaks between 2.825 and 2.575 ppm, and a much smaller, broad overlapping shoulder below 2.575 ppm, extending in some cases down to 2.4 ppm (for instance, for 510kPB4.7A polymer that shoulder peak was about 1/3 of the size of the first two). These observations indicate that the signal for HO 2 CCH 2 CH 2 SCH 2 -is broad, with significant overlap with the middle peak, and that for simplicity the 2.85-2.4 ppm range should be integrated as a whole, accounting for 6 protons for each functionalized monomer. The complication is that the integration of the small shoulder region between 2.55 and 2.4 ppm was found to be completely unreliable (due both to its small size at the very low extents of functionalization investigated, and apparently to the presence of the very large neighboring PB backbone peak): in many cases, the softwarecomputed integral was a physically nonsensical negative number. As a result, extents of MPA functionalization were approximated instead in all cases by integrating between 2.825 and 2.575 ppm and estimating that that integral accounted for 5 protons for each functionalized monomer. A.1.2 Extensional Viscosity ResultsFigure A.1 below reports apparent extensional viscosity for the solutions whose capillary breakup behavior is shown in Figure 13.A-1 A.2 Numerical Approach for Chain Statistics of Self-Associating Chains atInfinite Dilution in θ-Solvent A.2.1 Model DescriptionOur objective is to determine the size of a linear chain of N monomers, f of which are modified to act as stickers capable of forming pair-wise only, physical associations. The stickers are assumed to be equidistantly spaced l monomers apart along the chain, and the energy of association is εkT. We will assume Gaussian chain statistics for any segment of the chain whose configuration is unrestrained by reversible crosslinks.To calculate the size of the chain in the very dilute regime (all associations are intramolecular), we define a semi-Markov process X(t), t > 0 such that each state i is fully specified by identifying which pairs of stickers form bonds. (Note here that a given state has an infinite number of chain configurations.) The chain goes from one state to the next by either breaking or forming a bond, as illustrated in Figure A. Assume the polymer chain enters state i at time t. Clearly, the state it enters next is determined by which bond is broken or formed first; and the time spent in the present state is the time it took for that bond-breaking or bond-forming event to take place.B...

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“…Where, Ψ =[(σ w /σ l ) (µ l /µ w ) (ρ w /ρ l ) 2 ] 0.33 (4) To study the effect of drag reducing agent on flow boundary, a known quantity of xanthan gum (DRA) was added to water and the mixture was used as liquid phase, and the flow patterns were visually [13] also reported that with the addition of DRA, the interfacial shear stress decreases sharply and the flow pattern transition is altered. The boundary conditions for the various flow transitions were estimated by using the present experimental data which is listed in Table 3.…”

Section: Flow Regimes and Flow Regimes Transitionmentioning

confidence: 99%

Drag reduction in co-current down flow packed column using xanthan gum

Iyyaswami

JagadeeshBabu

Chitra

et al. 2010

Korean J. Chem. Eng.

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Drag reduction is one of the most important techniques for reducing energy consumption in a packed bed contactor. The present work involves an experimental investigation on flow regime transition for air-water system with and without drag reducing agent (DRA), two-phase pressure drop, friction factor and drag reduction using xanthan gum as DRA. Drag reduction was quantified from the two-phase pressure drop data. Based on the present observations it was found that the percentage drag reduction increases with an increase in the concentration of DRA and it is only effective in the range of 300 ppm to 800 ppm. The experimental results indicate that a maximum of 80% drag reduction was achievable using xanthan gum (800 ppm) as DRA. Furthermore, the experimental data were validated with the available literature correlations.

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Drag reduction in exceptionally dilute polymer solutions

Cited by 25 publications

References 1 publication

Drag reduction and solvation in polymer solutions

Drag reduction and solvation in polymer solutions

Effects of Pairwise, Self-Associating Functional Side Groups on Polymer Solubility, Solution Viscosity, and Mist Control

Drag reduction in co-current down flow packed column using xanthan gum

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