Numerical and Experimental Study of a Dual-Shaft Coaxial Mixer with Viscous Fluids

Farhat, Maya; Rivera, Christian; Fradette, Louis; Heniche, Mourad; Tanguy, Philippe A.

doi:10.1021/ie061226z

Cited by 31 publications

(18 citation statements)

References 14 publications

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“…) where is the central impeller diameter.These correlations were applicable for the speed ratios higher than 10. Rivera et al (2006) and Farhat et al (2007) utilized successfully the correlations developed by Foucault et al (2005). Later, Foucault et al (2006) defined the Reynolds number for both co-rotating and counter-rotating modes by applying the concept of Metzner-Otto for Newtonian and power law fluids as follows:…”

Section: Power Consumption Of the Coaxial Mixing Systemsmentioning

confidence: 99%

“…Their results showed good agreement with those reported by Thibault and Tanguy (2000). Farhat et al (2007) focused on the power consumption and mixing time of two coaxial systems: an axial impeller with an anchor and a radial impeller with an anchor. Their investigation proved that the efficiency of the system using axial mixer was better than that of the Rushton turbine with anchor.…”

Section: Power Consumption Of the Coaxial Mixing Systemsmentioning

confidence: 99%

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Mixing of complex fluids with coaxial mixers composed of two central impellers and an anchor

Kazemzadeh¹

2021

Preprint

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The coaxial mixers composed of a high-speed central impeller and a low-speed anchor have been recommended by the previous researchers for the mixing of highly viscous and non-Newtonian fluids. However, no study has been reported in the literature regarding the use of the coaxial mixing systems composed of two central impellers and an anchor in the agitation of complex fluids. Thus, the main objective of this study was to investigate the performance of coaxial mixers composed of two central impellers and an anchor in the agitation of the xanthan gum solution, which is a yield-pseudoplastic fluid, through electrical resistance tomography (ERT), the computational fluid dynamics (CFD), and design of experiments (DOE) combined with the response surface methodology (RSM). In the first stage of this study, the hydrodynamic performance of coaxial mixers, the single and double Scaba impellers in combination with an anchor impeller, was investigated in the mixing of yield-pseudoplastic fluids. Considering the mixing efficiency criteria, it was found that the double Scaba-anchor coaxial system was more efficient than the single Scaba-anchor coaxial mixer in the mixing of yield pseudoplastic fluids with regard to the mixing time and power drawn. In the second stage of this research project, the performances of three different coaxial mixers, namely, double Scaba-anchor coaxial (DSAC), double Rushton turbine-anchor coaxial (DRAC), and double pitched blade turbine-anchor coaxial (DPAC) mixers were assessed. It was found that the double Scaba-anchor coaxial (DSAC) mixer was more efficient system compared to the others at the same operating conditions. To evaluate the influence of the impeller spacing on the hydrodynamics of the double Scaba-anchor coaxial mixer, the lower impeller clearance and the spacing between two central impellers were changed within a wide range. The results demonstrated that a coaxial mixer with the impeller spacing of almost equal to the central impeller diameter was the most efficient configuration compared to the other cases. When the impeller spacing was varied, the merging flow and parallel flow patterns were observed. Finally, the hydrodynamic performances of different configurations of coaxial mixers composed of a wall scraping anchor impeller in combination with two different or identical central high-speed impellers were analyzed. The coaxial mixers utilized in this stage were the Scaba–Scaba-anchor (SSAC), Scaba-Rushton-anchor (SRAC), Rushton-Scaba-anchor (RSAC), Scaba-pitched blade-anchor (SPBAC), and pitched blade-Scaba-anchor (PBSAC). A new correlation was introduced for these complex configurations of the coaxial mixers by incorporating the Metzner-Otto constants (Ks) of the different types of the central impellers into the Reynolds number. The analysis of the collected data revealed that the Scaba-pitched blade-anchor coaxial (SPBAC) mixer was the most efficient mixing system in the mixing of the highly viscous non-Newtonian fluids.

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Section: Power Consumption Of the Coaxial Mixing Systemsmentioning

confidence: 99%

Section: Power Consumption Of the Coaxial Mixing Systemsmentioning

confidence: 99%

Mixing of complex fluids with coaxial mixers composed of two central impellers and an anchor

Kazemzadeh¹

2021

Preprint

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“…The mesh was initially partitioned into sliding and fixed subdomains. Once the hydrodynamic field is established, the power consumption, denoted by P, of the simulated scenario is obtained by [36] P = (s :ċ) d (30) Table III contrasts the numerical power consumption with the experimental results of Farhat et al [37], showing an error of 2.2% that demonstrates the validity of the solutions. These partitions were further subdivided to observe the parallel performance of the method as shown in Figure 13.…”

Section: Parallel Performancementioning

confidence: 99%

“…These partitions were performed with the help of spectral algorithms and Kerninghan-Lin smoothing techniques included in Chaco partitioning software [35]. Once the hydrodynamic field is established, the power consumption, denoted by P, of the simulated scenario is obtained by [36] P = (s :ċ) d (30) Table III contrasts the numerical power consumption with the experimental results of Farhat et al [37], showing an error of 2.2% that demonstrates the validity of the solutions. Table IV summarizes the parallel performance obtained for the different tests.…”

Section: Parallel Performancementioning

confidence: 99%

A parallel finite element sliding mesh technique for the simulation of viscous flows in agitated tanks

Rivera

Heniche

Bertrand

et al. 2011

Numerical Methods in Fluids

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SUMMARY A parallel sliding mesh algorithm for the finite element simulation of viscous fluid flows in agitated tanks is presented. Lagrange multipliers are used at the sliding interfaces to enforce the continuity between the fixed and moving subdomains. The novelty of the method consists of the coupled solution of the resulting velocity–pressure‐Lagrange multipliers system of equations by an ILU(0)‐QMR solver. A penalty parameter is introduced for both the interface and the incompressibility constraints to avoid pivoting problems in the ILU(0) algorithm. To handle the convective term, both the Newton–Raphson scheme and the semi‐implicit linearization are tested. A penalty parameter is introduced for both the interface and the incompressibility constraints to avoid the failure of the ILU(0) algorithm due to the lack of pivoting. Furthermore, this approach is versatile enough so that it allows partitioning of sliding and fixed subdomains if parallelization is required. Although the sliding mesh technique is fairly common in CFD, the main advantage of the proposed approach is its low computational cost due to the inexpensive and parallelizable calculations that involve preconditioned sparse iterative solvers. The method is validated for Couette and coaxial stirred tanks. Copyright © 2011 John Wiley & Sons, Ltd.

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“…The earliest work was reported by Schneider and Todtenhaupt of EKATO Company [7]. Afterwards, Canadian Tanguy's group did systematic researches on the performance of coaxial mixers, which were composed of an anchor agitator and Rushton turbine impeller or Sevin propeller or Deflo-Sevin impeller [8][9][10][11]. Their studies were mainly focused on the influences of rotation modes and speed ratios on power consumption and mixing performance.…”

Section: Introductionmentioning

confidence: 99%

Power consumption and flow field characteristics of a coaxial mixer with a double inner impeller

Liu

Zhang

Chen

et al. 2015

Chinese Journal of Chemical Engineering

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Numerical and Experimental Study of a Dual-Shaft Coaxial Mixer with Viscous Fluids

Cited by 31 publications

References 14 publications

Mixing of complex fluids with coaxial mixers composed of two central impellers and an anchor

Mixing of complex fluids with coaxial mixers composed of two central impellers and an anchor

A parallel finite element sliding mesh technique for the simulation of viscous flows in agitated tanks

Power consumption and flow field characteristics of a coaxial mixer with a double inner impeller

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