Pressure drop excess in the flow of viscoelastic liquids through fixed beds of particles

Bendová, Helena; Šiška, Bedřich; Machač, Ivan

doi:10.1016/j.cep.2008.04.001

Cited by 9 publications

(11 citation statements)

References 20 publications

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“…In their study of excess pressure drop flowing in a fixed bed of particles, Bendova et al 23 compare this effective viscoelastic time with commonly used characteristic times. The time scale of the Carreau law ( Table 2) is orders of magnitude larger, but the time scale based on elongational flow k E measured on a polymeric filament thinning gives satisfactory results.…”

Section: Excess Pressure Dropmentioning

confidence: 97%

“…However, this sharp increase of the friction factor with the flow rate has often been observed on flow of viscoelastic fluids in porous media. 23,31,32 Most of the porous media used for these studies were in fact packing beads. The increase in the friction factor in the case of viscoelastic fluids was explained and modeled by an elongation of the fluids going through the successively shrinking and expanding size of the interstice between the beads.…”

Section: Excess Pressure Dropmentioning

confidence: 99%

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Pressure drop in a split‐and‐recombine caterpillar micromixer in case of newtonian and non‐newtonian fluids

et al. 2013

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Microreactors are very promising tools for the design of future chemical processes. For example, emulsions of very narrow size distribution are obtained at much lower energy consumption than the one spent with usual processes. Micromixers play thereby an eminent role. The goal of this study is to better understand the hydrodynamic properties of a split-and-recombine Caterpillar micromixer (CPMM) specially with regard to handling viscoelastic fluids, a topic hardly addressed so far in the context of micromixers in general, although industrial fluids like detergent, cosmetic, or food emulsions are non-Newtonian. Friction factor was measured in a CPMM for both Newtonian and non-Newtonian fluids. For Newtonian fluids, the friction factor in the laminar regime is f/2 = 24/Re. The laminar regime exists up to Reynolds numbers of 15. For shear-thinning fluids like Carbopol 940 or viscoelastic fluids like Poly Acryl Amide (PAAm) aqueous solutions, the friction factor scales identically within statistical errors up to a generalized Reynolds number of 10 and 0.01, respectively. Above that limit, there is an excess pressure drop for the viscoelastic PAAm solution. This excess pressure drop multiplies the friction factor by more than a decade over a decade of Reynolds numbers. The origin of this excess pressure drop is the high elongational flow present in the Caterpillar static mixer applied to a highly viscoelastic fluid. This result can be extended to almost all static mixers, because their flows are generally highly elongational

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Section: Excess Pressure Dropmentioning

confidence: 97%

Section: Excess Pressure Dropmentioning

confidence: 99%

Pressure drop in a split‐and‐recombine caterpillar micromixer in case of newtonian and non‐newtonian fluids

et al. 2013

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“…The appropriate forms of the correction function f(De) have been proposed on the basis of solution of the flow of viscoelastic fluids through model diverging and converging channels [10]. Analogous to the flow through porous media, it can be anticipated that the concrete form of the correction function f(De) can be expressed as…”

Section: Theoreticalmentioning

confidence: 99%

“…Examples of viscosity function courses of 0.8% Praestol, 0.4% Kerafloc, and 0.6% Hercofloc are shown in Figure 3. The measure of non-linear elasticity of test liquids, which gives rise to pressure drop excess [10], was evaluated from the results of primary normal stress difference N 1 and elongation measurements. It was found that all test liquids exhibit a distinct non-linear elasticity.…”

Section: Rheological Characteristic Of Liquidsmentioning

confidence: 99%

Flow of Viscoelastic Polymer Solutions through Filter Screens

Machač¹,

Surý²,

Šiška³

et al. 2011

AIP Conference Proceedings

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Development of wavy texture in startup flows of liquid crystalline polymer solution through a slit cellAbstract. In this contribution, the measurements are presented of the pressure drop in the creeping flow of viscoelastic solution of polyacrylamides through metal wire screens, differing in wire diameter, aperture dimension, and type of weaving. In this flow, a strong elastic pressure drop excess manifest itself. Analysing the extensive set of experimental data, it was verified that for engineering estimation of the pressure drop excess, a simple form of the corrective Deborah number function can be used.

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“…In porous media flows, viscoelastic effects manifest themselves in the form of a pressure drop excess above that accountable by shear viscosity of the flowing liquid (e.g. [1]). At the same time, the pressure drop excess occurs only when the flow rate exceeds a limit value.…”

Section: Introductionmentioning

confidence: 99%

Cake Filtration in Viscoelastic Polymer Solutions

Surý¹,

Machač²

2009

AIP Conference Proceedings

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Sliding plate rheometer studies of concentrated polystyrene solutions: Nonlinear viscoelasticity and wall slip of two high molecular weight polymers in tricresyl phosphate Abstract. In this contribution, the filtration equations for a cake filtration in viscoelastic fluids are presented. They are based on a capillary hybrid model for the flow of a power law fluid. In order to express the elastic pressure drop excess in the flow of viscoelastic filtrate through the filter cake and filter screen, modified Deborah number correction functions are included into these equations. Their validity was examined experimentally. Filtration experiments with suspensions of hardened polystyrene particles (Krasten) in viscoelastic aqueous solutions of polyacryl amides (0.4 % and 0.6 %wt. Kerafloc) were carried out at a constant pressure on a cylindrical filtration unit using filter screens of different resistance.

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Pressure drop excess in the flow of viscoelastic liquids through fixed beds of particles

Cited by 9 publications

References 20 publications

Pressure drop in a split‐and‐recombine caterpillar micromixer in case of newtonian and non‐newtonian fluids

Pressure drop in a split‐and‐recombine caterpillar micromixer in case of newtonian and non‐newtonian fluids

Flow of Viscoelastic Polymer Solutions through Filter Screens

Cake Filtration in Viscoelastic Polymer Solutions

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