Application of Theoretical and Experimental Findings for Optimization of Mixing Processes and Equipment

Jirout, Tomáš; Jiroutová, Dita

doi:10.3390/pr8080955

Cited by 7 publications

(5 citation statements)

References 27 publications

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“…To allow comparability between scales, mixing time is considered as one of the characteristic parameters used to transfer the process in-between scales [12,13]. Apart from stirring speed, several studies have been published discussing the impact of impeller or vessel inserts on the mixing time [14][15][16][17]. These studies, as well as others [18][19][20][21][22][23][24][25][26][27][28], clearly show the benefits of computational fluid dynamics (CFD) simulations when evaluating the design of impeller geometry, including the choice of the turbulent model on the obtained results.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective

et al. 2021

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Multipurpose stirring and blending vessels equipped with various impeller systems are indispensable in the pharmaceutical industry because of the high flexibility necessary during multiproduct manufacturing. On the other hand, process scale-up and scale-down during process development and transfer from bench or pilot to manufacturing scale, or the design of so-called scale-down models (SDMs), is a difficult task due to the geometrical differences of used vessels. The present work comprises a hybrid approach to predict mixing times from pilot to manufacturing scale for geometrical nonsimilar vessels equipped with single top, bottom or multiple eccentrically located impellers. The developed hybrid approach is based on the experimental characterization of mixing time in the dedicated equipment and evaluation of the vessel-averaged energy dissipation rate employing computational fluid dynamics (CFD) using single-phase steady-state simulations. Obtained data are consequently used to develop a correlation of mixing time as a function of vessel filling volume and vessel-averaged energy dissipation rate, which enables the prediction of mixing times in specific vessels based on the process parameters. Predicted mixing times are in good agreement with those simulated using time-dependent CFD simulations for tested operating conditions.

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Section: Introductionmentioning

confidence: 99%

Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective

et al. 2021

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“…The power number for a similar system was found in reference [27]. It was a pitched four-blade turbine with pitch angle α = 45 • , and with the ratio of the diameter of the vessel to the diameter of the stirrer D/d = 3.…”

Section: Flow Descriptionmentioning

confidence: 97%

“…By using baffles, the circulatory motion of the flow is hindered, so that it is directed also in the axial direction. The power number for a similar system was found in reference [27]. It was a pitched four-blade turbine with pitch angle α = 45°, and with the ratio of the diameter of the vessel to the diameter of the stirrer D/d = 3.…”

Section: Flow Descriptionmentioning

confidence: 98%

Digital Twinning Process for Stirred Tank Reactors/Separation Unit Operations through Tandem Experimental/Computational Fluid Dynamics (CFD) Simulations

Oblak¹,

Babnik²,

Erklavec-Zajec³

et al. 2020

Processes

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Computational fluid dynamics simulations (CFD) were used to evaluate mixing in baffled and unbaffled vessels. The Reynolds-averaged Navier−Stokes k–ε model was implemented in OpenFOAM for obtaining the fluid flow field. The 95% homogenization times were determined by tracer tests. Experimental tests were conducted by injecting sodium chloride into the vessel and measuring the conductivity with two conductivity probes, while the simulations replicated the experimental conditions with the calculation of the transport of species. It was found that the geometry of the system had a great effect on the mixing time, since the irregular flow distribution, which can be obtained with baffles, can lead to local stagnation zones, which will increase the time needed to achieve the homogenization of the solute. It was also found that measuring local, pointwise concentrations can lead to a high underestimation of the global mixing time required for the homogenization of the entire vessel. Dissolution of sucrose was also studied experimentally and by mathematical modeling. The dissolution of sucrose was found to be kinetically limited and a very good agreement was found between the experiments and the modeling approach. The extent of the applicability of CFD simulations was evaluated for enabling rapid process design via simulations.

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“…Because low temperature is an important parameter of the anodization process, it is relevant to select a suitable mixing impeller to ensure uniform electrolyte temperature throughout the reactor volume. A mechanical rotary stirrer is often used to create forced flow in the reactor [48]. The mixing process simulations were performed using ANSYS 17 software.…”

Section: Mixing Analysismentioning

confidence: 99%

Development and Analysis of Electrochemical Reactor with Vibrating Functional Element for AAO Nanoporous Membranes Fabrication

Cigane

Palevičius

Jurenas

et al. 2022

Sensors

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Nanoporous anodic aluminum oxide (AAO) is needed for a variety of purposes due to its unique properties, including high hardness, thermal stability, large surface area, and light weight. Nevertheless, the use of AAO in different applications is limited because of its brittleness. A new design of an electrochemical reactor with a vibrating element for AAO nanoporous membranes fabrication is proposed. The vibrating element in the form of a piezoceramic ring was installed inside the developed reactor, which allows to create a high-frequency excitation. Furthermore, mixing and vibration simulations in the novel reactor were carried out using ANSYS 17 and COMSOL Multiphysics 5.4 software, respectively. By theoretical calculations, the possibility to excite the vibrations of five resonant modes at different frequencies in the AAO membrane was shown. The theoretical results were experimentally confirmed. Five vibration modes at close to the theoretical frequencies were obtained in the novel reactor. Moreover, nanoporous AAO membranes were synthesized. The novel aluminum anodization technology results in AAO membranes with 82.6 ± 10 nm pore diameters and 43% porosity at 3.1 kHz frequency excitation and AAO membranes with 86.1 ± 10 nm pore diameters and 46% porosity at 4.1 kHz frequency excitation. Furthermore, the chemical composition of the membrane remained unchanged, and the hardness decreased. Nanoporous AAO has become less brittle but hard enough to be used for template synthesis.

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Application of Theoretical and Experimental Findings for Optimization of Mixing Processes and Equipment

Cited by 7 publications

References 27 publications

Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective

Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective

Digital Twinning Process for Stirred Tank Reactors/Separation Unit Operations through Tandem Experimental/Computational Fluid Dynamics (CFD) Simulations

Development and Analysis of Electrochemical Reactor with Vibrating Functional Element for AAO Nanoporous Membranes Fabrication

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