scholarly journals Application of CFD to Analyze the Hydrodynamic Behaviour of a Bioreactor with a Double Impeller

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 694 ◽  
Author(s):  
Ebrahimi ◽  
Tamer ◽  
Villegas ◽  
Chiappetta ◽  
Ein-Mozaffari
Keyword(s):  
Mixing Time ◽  
Gradient Flow ◽  
Total Power ◽  
Flow Number ◽  
Operational Parameter ◽  
Mixing Performance ◽  
Unit Operations ◽  
Hydrodynamic Behaviour ◽  
High Level ◽  
Rushton Impeller

Stirred bioreactors are commonly used unit operations in the pharmaceutical industry. In this study, computational fluid dynamics (CFD) was used in order to analyze the influence of the impeller configuration (Segment–Segment and Segment–Rushton impeller configurations) and the impeller rotational speed (an operational parameter) on the hydrodynamic behaviour and mixing performance of a bioreactor equipped with a double impeller. A relatively close agreement between the power values obtained from the CFD model and those measured experimentally was observed. Various parameters such as velocity profiles, stress generated by impellers due to the turbulence and velocity gradient, flow number, and mixing time were used to compare the CFD simulations. It was observed that the impeller’s RPM could change the intensity of the interaction between the impellers when a Segment–Rushton impeller was used. In general, increasing the RPM led to an increase in total power and the stress acting on the cells and to a shorter mixing time. At a constant RPM, the Segment–Rushton impeller configuration had higher total power and stress acting on cells compared to the Segment–Segment impeller configuration. At lower RPM values (i.e., 50 and 100), the Segment–Segment impeller provided a shorter mixing time. Conversely, at the highest RPM (i.e., 150) the Segment–Rushton impeller had a shorter mixing time compared to the Segment–Segment impeller; this was attributed to the high level of turbulence generated with the former impeller configuration at high RPM.

scholarly journals Effect of Aspect Ratio on the Mixing Performance in the Kenics Static Mixer

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 464
Author(s):  
Xingren Jiang ◽  
Ning Yang ◽  
Rijie Wang
Keyword(s):  
Pharmaceutical Industry ◽  
Aspect Ratio ◽  
Flow Reactor ◽  
Mixing Time ◽  
Continuous Process ◽  
Scale Up ◽  
Influence Factors ◽  
Continuous Manufacturing ◽  
Static Mixer ◽  
Mixing Performance

Continuous manufacturing has received increasing interest because of the advantages of intrinsic safety and enhanced mass transfer in the pharmaceutical industry. However, the difficulty for scale-up has limited the application of continuous manufacturing for a long time. Recently, the tubular flow reactor equipped with the Kenics static mixer appears to be a solution for the continuous process scale-up. Although many influence factors on the mixing performance in the Kenics static mixer have been investigated, little research has been carried out on the aspect ratio. In this study, we used the coefficient of variation as the mixing evaluation index to investigate the effect of the aspect ratio (0.2–2) on the Kenics static mixer’s mixing performance. The results indicate that a low aspect ratio helps obtain a shorter mixing time and mixer length. This study suggests that adjusting the aspect ratio of the Kenics static mixer can be a new strategy for the scale-up of a continuous process in the pharmaceutical industry.

New results of Boda Claystone research: Genesis, mineralogy, geochemistry, petrophysics

2018 ◽  
Vol 482 (1) ◽  
pp. 75-92 ◽  
Author(s):  
Ferenc Fedor ◽  
Zoltán Máthé ◽  
Péter Ács ◽  
Péter Koroncz
Keyword(s):  
High Level Waste ◽  
Swelling Clays ◽  
Theoretical Approaches ◽  
Hydrodynamic Behaviour ◽  
Geological Formation ◽  
Porosity And Permeability ◽  
History Of ◽  
Surrounding Areas ◽  
High Level ◽  
Low Porosity

AbstractBoda Claystone is a very tight clayey rock with extreme low porosity and permeability, nano-size pores and small amounts of swelling clays. Due to this character it is ideal as a potential host rock for research into the possibilities of high-level waste deposition in geological formation. Though the research started more than 30 years ago, the genesis, the geotectonic history of the Boda Claystone Formation (BCF) and the geology of surrounding areas has only been sketched out recently. On the basis of research of the past few years the process of sedimentation of different blocks was able to be reconstructed. Equipment and methodological developments were needed for the investigation of reservoir geological and hydrodynamic behaviour of this rock, which began in the early 2000s. Based on them the pore structure and reservoir could be characterized in detail. Only theoretical approaches were available for the chemical composition of free porewater. Traditional water-extracting methods were not adaptable because of excessively low porosity and nano-scale pore size distribution. Hence, new ways have to be found for getting enough water for analysis. These new results of BCF research help to prepare more sophisticated and directed experiments, in which there is a great interest internationally.

scholarly journals Stochastic parcel tracking in an Euler-Lagrange compartment model for fast simulation of fermentation processes

2021 ◽  
Author(s):  
Cees Haringa ◽  
Wenjun Tang ◽  
Henk Noorman
Keyword(s):  
Cellular Response ◽  
Cfd Simulation ◽  
Mixing Time ◽  
Compartment Model ◽  
Reaction Model ◽  
Heterogeneous Environments ◽  
Cfd Simulations ◽  
Fermentation Processes ◽  
Spatially Resolved ◽  
Unit Operations

Compartment modeling (CM) is a well-known approach for computationally affordable, spatially-resolved hydrodynamic modeling of unit operations. Recent implementations use flow profiles based on CFD simulations, and several authors included microbial kinetics to simulate gradients in bioreactors. However, these studies relied on black-box kinetics, that do not account for intra-cellular changes and cell population dynamics in response to heterogeneous environments. In this paper, we report the implementation of a Lagrangian reaction model, where the microbial phase is tracked as a set of biomass-parcels, each linked with an intra-cellular composition vector and a structured reaction model describing their intra-cellular response to extracellular variations. A stochastic parcel tracking approach is adopted, in contrast to the resolved trajectories used in prior CFD implementations. A penicillin production process is used as a case-study. We show good performance of the model compared to full CFD simulations, both regarding the extra-cellular gradients and intra-cellular pool response, provided the mixing time in the CM matches the full CFD simulation; taking into account that the mixing time is sensitive to the number of compartments. The sensitivity of the model output towards some of the inputs is explored. The coarsest representative CM requires a few minutes to solve 80 hours of flow time, compared to approx. 2 weeks for a full Euler-Lagrange CFD simulation of the same case. This alleviates one of the major bottlenecks for the application of such CFD simulations towards analysis and optimization of industrial fermentation processes.

Efficient Assessment of Physico-Chemical Properties of the Cryolite Melts for Research on the Improvement of Low-Temperature Aluminum Electrolysis

2018 ◽  
Vol 284 ◽  
pp. 839-844 ◽  
Author(s):  
V.A. Lebedev ◽  
Andrey A. Shoppert
Keyword(s):  
Low Temperature ◽  
Chemical Properties ◽  
Aluminum Electrolysis ◽  
Total Power ◽  
Potassium Cryolite ◽  
High Magnitude ◽  
Rate Of Dissolution ◽  
Physico Chemical ◽  
Hazardous Production ◽  
High Level

Modern aluminum electrolysis in cryolite-alumina melts is energy-intensive, inefficient and environmentally hazardous production. Addressing these significant shortcomings, the technology of low-temperature electrolyte is directed. The basis of low-temperature electrolysis is potassium cryolite, which results in high magnitude and rate of dissolution of alumina. Additive of sodium and lithium fluorides provide the necessary conductivity. Experimental investigation of these properties is extremely time consuming. In this work, as a parameter, which will allow to characterize effectively and rapidly the complexing ability of cryolite melts, the ratio of cationic ion power of Al3+ to the total power of the other cations of the melt is proposed. Regression analyses of the known experimental data establish the existence with a high level of reliability (R2=0.966-0.995) of a directly proportional dependence of this parameter on solubility of alumina and electrical conductivity of cryolite melts.

scholarly journals Laminar Mixing in Stirred Tank Agitated by an Impeller Inclined

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Koji Takahashi ◽  
Yoshiharu Sugo ◽  
Yasuyuki Takahata ◽  
Hitoshi Sekine ◽  
Masayuki Nakamura
Keyword(s):  
Numerical Simulation ◽  
Laminar Flow ◽  
Mixing Time ◽  
Flow Region ◽  
Experimental Results ◽  
Stirred Tank ◽  
Simulation Methods ◽  
Mixing Performance ◽  
Laminar Mixing ◽  
Numerical Simulation Methods

The mixing performance in a vessel agitated by an impeller that inclined itself, which is considered one of the typical ways to promote mixing performance by the spatial chaotic mixing, has been investigated experimentally and numerically. The mixing time was measured by the decolorization method and it was found that the inclined impeller could reduce mixing time compared to that obtained by the vertically located impeller in laminar flow region. The effect of eccentric position of inclined impeller on mixing time was also studied and a significant reduction of mixing time was observed. To confirm the experimental results, the velocity profiles were calculated numerically and two novel numerical simulation methods were proposed.

scholarly journals Finite Element Simulation and Performance Test of Loading and Mixing Characteristics of Self-Propelled Total Mixed Ration Mixer

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Fuyang Tian ◽  
Yuhua Chen ◽  
Zhanhua Song ◽  
Yinfa Yan ◽  
Li Fade ◽  
...  
Keyword(s):  
Finite Element ◽  
Power Consumption ◽  
Performance Test ◽  
Simulation Analysis ◽  
Mixing Time ◽  
Equivalent Strain ◽  
Total Mixed Ration ◽  
Mixing Performance ◽  
Optimum Parameters ◽  
Material Mixing

Simulation analysis and parameter optimization are performed for the loading and mixing devices of a self-propelled total mixed ration mixer. To reveal the three-dimensional movement of silage material under the action of the loading cutter roller, the latter is modeled using SolidWorks software. ANSYS/LS-DYNA software is used to simulate the process of silage cutting, which is modeled using smoothed particle hydrodynamics coupled with the finite element method. The cutting force and power consumption are simulated, and the behavior of the equivalent strain of the silage is determined. The results showed that silage was broken up mainly by extrusion and shear force due to the loading cutter roller. The power consumption according to the simulation is consistent with the value from an empirical formula, confirming the validity of the proposed modeling method. To study the mixing performance and obtain the optimum parameters of the mixing device, the Hertz–Mindlin model is used for the interaction between material particles and mixing device. A three-factor, five-level method is used to optimize the mixing performance. Material-mixing time, loading rate, and auger speed are chosen as experimental factors and mixed uniformity as an evaluation index. It is found that auger speed and material mixing time have significant effects on mixing uniformity. These results provide reference values allowing the analysis of the crushing of silage and selection of the optimum parameters for mixing performance.

scholarly journals Understanding Interdependencies between Mechanical Velocity and Electrical Voltage in Electromagnetic Micromixers

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 636 ◽  
Author(s):  
Noori Kim ◽  
Wei Xuan Chan ◽  
Sum Huan Ng ◽  
Yong-Jin Yoon ◽  
Jont B. Allen
Keyword(s):  
Fluorescent Dyes ◽  
Mixing Time ◽  
Electrical Measurement ◽  
Micro Electro Mechanical Systems ◽  
Mixing Performance ◽  
Micro Total Analysis Systems ◽  
Mechanical Behaviours ◽  
Total Analysis ◽  
Critical Components ◽  
Insight Into

Micromixers are critical components in the lab-on-a-chip or micro total analysis systems technology found in micro-electro-mechanical systems. In general, the mixing performance of the micromixers is determined by characterising the mixing time of a system, for example the time or number of circulations and vibrations guided by tracers (i.e., fluorescent dyes). Our previous study showed that the mixing performance could be detected solely from the electrical measurement. In this paper, we employ electromagnetic micromixers to investigate the correlation between electrical and mechanical behaviours in the mixer system. This work contemplates the “anti-reciprocity” concept by providing a theoretical insight into the measurement of the mixer system; the work explains the data interdependence between the electrical point impedance (voltage per unit current) and the mechanical velocity. This study puts the electromagnetic micromixer theory on a firm theoretical and empirical basis.

Experimental Investigation of the Use of Synthetic Jets for Mixing in Vessels

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Mushtak Al-Atabi
Keyword(s):  
Mixing Time ◽  
Synthetic Jets ◽  
Stirred Tank ◽  
Fluid Viscosity ◽  
Stirred Tank Reactors ◽  
Mixing Performance ◽  
Shear Rates ◽  
Local Shear ◽  
Continuously Stirred Tank Reactor ◽  
Visualization Techniques

Mixing is an important process in various industries. Different designs have been suggested in order to reduce the local shear rates in mechanically stirred mixing vessels, also known as continuously stirred tank reactors, in order to account for the mixing requirements for sensitive materials such as biological materials and biofluids where the high shear rate may damage the sensitive materials. This paper reports on the development of a continuously stirred tank reactor that can be used to achieve a variety of mixing assignments. This mixing is achieved using synthetic jets. The mixing performance was assessed using flow visualization techniques. The effects of fluid viscosity on mixing time were investigated. The results are very encouraging and are suggestive that the use of synthetic jets in mixing is a viable alternative to the conventional methods of mixing in vessels.

scholarly journals POWER ESTIMATOR DEVELOPMENT FOR EMBEDDED SYSTEM MEMORY TUNING

2002 ◽  
Vol 11 (05) ◽  
pp. 459-475
Author(s):  
FRANK VAHID ◽  
TONY GIVARGIS ◽  
SUSAN COTTERELL
Keyword(s):  
Embedded System ◽  
Memory Hierarchy ◽  
Total Power ◽  
Accurate Estimation ◽  
System Memory ◽  
The Embedded System ◽  
Memory Accesses ◽  
And Performance ◽  
The One ◽  
High Level

Memory accesses account for a large percentage of total power in microprocessor-based embedded systems. The increasing use of microprocessor cores and synthesis, rather than prefabricated microprocessor chips, creates the opportunity to tune a memory hierarchy to the one program that will execute in the embedded system. Such tuning requires fast and accurate estimation of the power and performance of different memory configurations. We describe a general three-step approach to developing such estimators, based on our experiences on several different projects. Each step is increasingly fast, using the previous step to gauge accuracy. The first step uses high-level functional simulation, the second step uses trace simulation, and the third step uses equations. A tool developer can follow these three steps to create a powerful environment for core users to support synthesis of the best memory hierarchy for a particular embedded system. The approach can be applied to components other than memory also.

High-Level Containment Care Unit Operations

2020 ◽  
pp. 59-86
Author(s):  
AURORA B. LE ◽  
JOHN J. LOWE ◽  
SCOTT J. PATLOVICH ◽  
ROBERT EMERY ◽  
ELIZABETH L. BEAM ◽  
...  
Keyword(s):  
Unit Operations ◽  
High Level
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