Computational Fluid Dynamics Study of Flow Induced by a Grooved High‐Shear Impeller in an Unbaffled Tank

Jesús, Gaston Martínez-de; Ramírez-Muńoz, J.; García-Cortés, Daniel; Cota, Luis G.

doi:10.1002/ceat.201700091

Cited by 9 publications

(8 citation statements)

References 11 publications

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“…Regarding the ε̅ calculated from the experimental values of power and , it was found that simulations present lower values by 36.3 and 38.4% (mean 37.35%) at 300 and 500 rpm, respectively. Under-prediction of ε̅ using CFD has been reported in other studies, for example, using large eddy simulation and detached eddy simulation by 25 to 45%, which is compatible with the 37.35% average value obtained in this work. − Based on the percentage of under-prediction obtained, the results of the hydrodynamic stress were corrected ( ), increasing the values of ε̅ by 37.35%. The volume-weighted average hydrodynamic stresses at 300 rpm are shown in Table .…”

Section: Resultssupporting

confidence: 88%

“…It is important to point out that in other studies, shorter and longer experimental values of mixing times than the simulated values have been reported. − It can be explained because the RANS models do not capture the transient turbulent structures due to the dampening effect . The experimental and CFD θ 95% results obtained are in good agreement.…”

Section: Resultsmentioning

confidence: 64%

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Power Consumption and Energy Dissipation Rate Reduction in Agitated Tanks by Control Rods Attached to a Pitched Blade Impeller

Mendoza-Escamilla

Rivadeneyra-Romero²,

González-Neria

et al. 2022

Ind. Eng. Chem. Res.

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The effects of axially symmetric control rods added to the archetypal four-blade pitched blade turbine (PBT) have been evaluated. The convectional PBT and two control rod configurations were tested (P2 and P3). Modifications resulted in a significant improvement in the hydrodynamic performance of the PBT impeller. Experimental measurements of torque and mixing time have been obtained, as well as flow measurement through particle image velocimetry (PIV) techniques to validate and compare the results obtained through numerical simulation using computational fluid dynamics. All these experimental tests and simulations have been used to evaluate the hydrodynamic behavior of these rod-controlled impellers. It was found that the modified PBT with control rods shows reduced power consumption compared to the conventional PBT. The use of control rods has achieved a reduction of up to 12.18% in the power number. It was found that the control rods reduce the fluid separation, reducing the pressure drag and the suction pressure zones on the rear of the blade, thus reducing the power consumption. Despite the reduction in the pumping number for the two configurations proposed, pumping efficiency is not greatly affected. For configuration P3, the efficiency is similar to that of the PBT. It is worth highlighting that all the control rods evaluated showed a reduction in the energy dissipation rate, and for the best case, P3, a maximum of 17.02% reduction was achieved. The reduction in the energy dissipation rate may be useful in applications that require low shearing stresses during processing. Also, the same impeller design may decrease the energy consumption during long-term processing tasks.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 64%

Power Consumption and Energy Dissipation Rate Reduction in Agitated Tanks by Control Rods Attached to a Pitched Blade Impeller

Mendoza-Escamilla

Rivadeneyra-Romero²,

González-Neria

et al. 2022

Ind. Eng. Chem. Res.

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“…From Eqs, (11), , (14) and (15), the Newtonian and non-Newtonian N P curves as a function of Re (or Re a ) can be obtained. For the laminar regime, N P is inversely proportional to Re, i.e.,…”

Section: Experimental and Numerical Calculation Of The Metzner-otto Cmentioning

confidence: 99%

“…It has been reported that the impeller-induced maximum values of shear, or viscous dissipation in the laminar regime, determines the ultimate particle size in solid-liquid dispersions [9,10]. In the laminar regime, maximum values of shear rate and its associated shear stress correspond with maximum values of viscous dissipation; therefore, these three hydrodynamic parameters are frequently related to the ultimate particle size in actual pigment dispersion processes [3,[9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Performance of a Ring‐Style High‐Shear Impeller in Newtonian and Shear‐Thinning Fluids

et al. 2020

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Laminar mixing of Newtonian and shear-thinning fluids induced by a Hockmeyer-type impeller was investigated. Two unbaffled tanks at three impellers off-bottom clearances (c) were studied. Six geometric combinations, i.e., two d/T and three c/T, were examined where d and T are the impeller and tank diameters, respectively. Determination of the Metzner-Otto constant (K s) was undertaken. The effects of d/T, c/T, and fluid rheology on K s , power demand, pumping, shear and viscous dissipation were analyzed. The evaluated geometric ratios and rheology do not significantly affect K s and power demand, only the rheology had an impact on the remaining hydrodynamic parameters. Pumping was favored with the Newtonian fluid, and shear and viscous dissipation increased with the shearthinning fluid.

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“…Before titanium-dioxide powder can be used as a paint, its structure has to be broken into smaller parts. This process is performed in special devices such as ball mills [9,10] and high shear mixers [11,12]. Ultrasonication [5,13] and high-pressure nozzles [13][14][15][16] are often applied.…”

Section: Introductionmentioning

confidence: 99%

Population Balance Application in TiO2 Particle Deagglomeration Process Modeling

et al. 2021

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The deagglomeration of titanium-dioxide powder in water suspension performed in a stirring tank was investigated. Owing to the widespread applications of the deagglomeration process and titanium dioxide powder, new, more efficient devices and methods of predicting the process result are highly needed. A brief literature review of the application process, the device used, and process mechanism is presented herein. In the experiments, deagglomeration of the titanium dioxide suspension was performed. The change in particle size distribution in time was investigated for different impeller geometries and rotational speeds. The modification of impeller geometry allowed the improvement of the process of solid particle breakage. In the modelling part, numerical simulations of the chosen impeller geometries were performed using computational-fluid-dynamics (CFD) methods whereby the flow field, hydrodynamic stresses, and other useful parameters were calculated. Finally, based on the simulation results, the population-balance with a mechanistic model of suspension flow was developed. Model predictions of the change in particle size showed good agreement with the experimental data. Using the presented method in the process design allowed the prediction of the product size and the comparison of the efficiency of different impeller geometries.

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Computational Fluid Dynamics Study of Flow Induced by a Grooved High‐Shear Impeller in an Unbaffled Tank

Cited by 9 publications

References 11 publications

Power Consumption and Energy Dissipation Rate Reduction in Agitated Tanks by Control Rods Attached to a Pitched Blade Impeller

Power Consumption and Energy Dissipation Rate Reduction in Agitated Tanks by Control Rods Attached to a Pitched Blade Impeller

Hydrodynamic Performance of a Ring‐Style High‐Shear Impeller in Newtonian and Shear‐Thinning Fluids

Population Balance Application in TiO2 Particle Deagglomeration Process Modeling

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