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Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna; Bílek, V.; Haidl, J.; Isoz, Martin; Pivokonský, M.
2024 - English
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
Keywords:
flocculation tank; stirring; MRF; CFD; OpenFOAM
Available at various institutes of the ASCR
Flow simulations approach for flocculation tanks
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and ...
Improvement of an unbaffled stirred tank mixing characteristics using variable speed impeller
Gebouský, Ondřej; Haidl, Jan; Bodnár, J.; Pivokonský, Martin
2024 - English
Unbaffled mixing tanks with magnetically driven impellers are increasingly used in biotechnological and pharmaceutical industries, combining the benefits of a closed, sterile environment with easy equipment cleanability. On the other hand, missing internals, such as baffles or cooling coils, have an adverse effect on the equipment mixing characteristics, namely the batch\nhomogenization time. In our previous research, we uncovered that the eccentricity and inclination of the impeller – both employed routinely to enhance the mixing characteristics of unbaffled vessels – are not fully effective in the suppression of central vortex formation resulting in the increase in the homogenization time. In this work, we propose a simple solution to counteract the central vortex formation – a periodical variation of impeller rotational speed. This approach destabilizes the central vortex, significantly reducing homogenization time while maintaining the benefits of the original unbaffled setup. This innovation can seamlessly integrate into existing industrial setups, promising efficiency gains for biotech and pharmaceutical production.
Keywords:
unbaffled mixing tanks; variable rotational speed; vortex destabilization; mixing time improvement
Available in digital repository of the ASCR
Improvement of an unbaffled stirred tank mixing characteristics using variable speed impeller
Unbaffled mixing tanks with magnetically driven impellers are increasingly used in biotechnological and pharmaceutical industries, combining the benefits of a closed, sterile environment with easy ...
A New Hollow Fiber-Based Liquid-Phase Microextraction Method for the Determination of Antihypertensive Drug Lercanidipine in Biological Samples
Labzova, O.; Hrdlička, Vojtěch; Navrátil, Tomáš; Šelešovská, R.
2024 - English
A new hollow fiber-based liquid-phase microextraction (HF-LPME) method for the determination of antihypertensive drug lercandipine (LCN) in biological samples was developed. HF-LPME was\ncombined with optimized square wave voltammetry (SWV) on a cathodically pre-treated screenprinted boron-doped diamond electrode (SP-BDDE). Optimum HF-LPME conditions were:\nsupported liquid membrane (SLM) dodecane, 0.02 mol L-1 Britton-Robinson buffer (BRB, pH = 3) acceptor phase, BRB (pH = 7) donor phase, and time of extraction 30 min. Limits of quantification (LOQ) and detection (LOD) were 3.3 and 1.1 nmol L-1, respectively. The applicability of the developed method was verified on human urine, blood serum, and blood plasma with 20 and 100 nmol L-1 LCN addition.
Keywords:
Lercanidipine hydrochloride; Hollow fiber liquid-phase microextraction; Screenprinted boron-doped diamond electrode
Available on request at various institutes of the ASCR
A New Hollow Fiber-Based Liquid-Phase Microextraction Method for the Determination of Antihypertensive Drug Lercanidipine in Biological Samples
A new hollow fiber-based liquid-phase microextraction (HF-LPME) method for the determination of antihypertensive drug lercandipine (LCN) in biological samples was developed. HF-LPME was\ncombined with ...
Kultura České republiky v číslech 2023:
Dedera, Milan; NIPOS, Národní informační a poradenské středisko pro kulturu
2024 - Czech
Statistika kultury se zabývá zjišťováním údajů o činnosti kulturních subjektů (např. návštěvnost, kapacita, vzdělávací akce, vydané publikace, výpůjčky, čtenáři). V předkládané brožuře jsou zveřejněny vybrané údaje za následující obory: divadlo, galerie, muzea a památníky, hvězdárny, planetária a astronomické pozorovatelny, veřejné knihovny, památkové objekty zpřístupněné za vstupné, neperiodické publikace a periodický tisk. Údaje ekonomické povahy jsou k dispozici pouze za subjekty veřejného sektoru, kulturní subjekty v soukromém sektoru je neposkytují.
Keywords:
divadelní představení; galerie; hudební tělesa; knihovny; kultura a společnost; muzea; nakladatelství; návštěvnost; památkové objekty; statistika; umění a společnost; výstavnictví; ancient monuments; art and society; culture and society; ensembles; galleries; libraries; museums; numbers of visitors; organization of exhibitions; publishing houses; statistics; theatrical perfomances
Available in a digital repository NRGL
Kultura České republiky v číslech 2023:
Statistika kultury se zabývá zjišťováním údajů o činnosti kulturních subjektů (např. návštěvnost, kapacita, vzdělávací akce, vydané publikace, výpůjčky, čtenáři). V předkládané brožuře jsou zveřejněny ...
Gas sensors based on diamond heterostructures for air quality monitoring
Kočí, Michal; Szabó, Ondrej; Izsák, T.; Sojková, M.; Godzierz, M.; Wróbel, P.; Husák, M.; Kromka, Alexander
2024 - English
Currently, great emphasis is placed on air quality and the presence of pollutants. Attention is therefore focused on new gas-sensing materials enabling detection even at low (up to room) temperatures with sufficient response and short reaction time. Here, we investigate the suitability of H-NCD films and their heterostructures with MoS2, GO, rGO, SH-GO, or Au NPs for gas sensing applications. Electrical properties are measured for oxidizing gas NO2, reducing gas NH3, and chemical vapor of ethanol, and at temperatures varied from room temperature to 125 °C. In contrast to the individual forms of employed materials with limited response to the exposed gases, the HNCD heterostructures revealed better sensing properties. In particular, the Au NPs/H-NCD heterostructures revealed a higher response at 125 °C in contrast to H-NCD, MoS2/H-NCD had quite good response even at room temperature and GO/H-NCD revealed high sensitivity to chemical vapor, which further improved for the SH-GO/HNCD.
Keywords:
gas sensors; nanocrystalline diamond; heterostructures; air quality monitoring
Fulltext is available at external website.
Gas sensors based on diamond heterostructures for air quality monitoring
Currently, great emphasis is placed on air quality and the presence of pollutants. Attention is therefore focused on new gas-sensing materials enabling detection even at low (up to room) temperatures ...
Development of Polymeric Enantioselective Membranes
Čížek, Jan
2024 - English
Enantiomers are molecules that share the same chemical formula but in space form mirror images of each other. Their reactions with other chiral molecules can be remarkably different, which is crucial mainly for pharmaceuticals and agrochemicals. However, industrialscale synthetic production of enantiomerically pure compounds is not always available. Therefore, the need for pure enantiomeric compounds drives the development and research on various separation methods. However, most methods used on the industrial scale are limited to specific compounds (diastereomeric recrystallization) or generally difficult and/or expensive to scale up (chromatography-related methods). Separation of enantiomers using membranes is promising\nthanks to the easy scalability and continuous operation of membrane processes. Various ideas about how the enantioselective membranes should look like have been published in the last thirty years. The mechanism of enantiomeric separation on a membrane is, however, highly specific, and still requires extensive research. In this work, four types of enantioselective polymeric membranes are presented.
Available in a digital repository NRGL
Development of Polymeric Enantioselective Membranes
Enantiomers are molecules that share the same chemical formula but in space form mirror images of each other. Their reactions with other chiral molecules can be remarkably different, which is crucial ...
Synthesis of Fluorinated Methyl β-Lactosides
Krčil, Aleš
2024 - English
In my contribution, I will describe the synthesis of a complete series of mono-deoxyfluorinated methyl β-lactosides (1–7). Their affinity towards hgals will be determined by analytical method ELISA. The synthesis relies on monosaccharide building blocks, which serves as key intermediates that are transformed into the target products through glycosylation followed by final deprotection steps.
Keywords:
flurinated carbohydrates; galectin; deoxyfluorination
Available in a digital repository NRGL
Synthesis of Fluorinated Methyl β-Lactosides
In my contribution, I will describe the synthesis of a complete series of mono-deoxyfluorinated methyl β-lactosides (1–7). Their affinity towards hgals will be determined by analytical method ELISA. ...
Investigation of Mechanical Processing of Solar Photovoltaic Panels
Šperlich, Antonín
2024 - English
This work aims to describe the possibilities of mechanical treatment of solar photovoltaic panels. In the first part, the shredding and milling process for the transformation of the product (whole panel) into material that can be further processed, was investigated. Milled material was sieved and analyzed. It was observed that this shredding also works as a selective grinding because three main products were produced. The second part of this work was aimed at the physical concentration of silver in real samples of milled solar photovoltaic panels by Knelson separator. This device (type of centrifugal separator) showed the ability to significantly increase the amount of silver in the outcome stream.
Keywords:
solar photovoltaic panels; selective milling; Knelson
Available in a digital repository NRGL
Investigation of Mechanical Processing of Solar Photovoltaic Panels
This work aims to describe the possibilities of mechanical treatment of solar photovoltaic panels. In the first part, the shredding and milling process for the transformation of the product (whole ...
Axial Dispersion and Mass Transfer in Bubble Column
Terentyak, Mark
2024 - English
The objective of the study is to experimentally investigate axial dispersion and mass transfer within a bubble column, examining their mutual interrelation\nand their correlation with operational parameters and AR1.
Keywords:
bubble column; axial dispersion; mass transfer
Available in a digital repository NRGL
Axial Dispersion and Mass Transfer in Bubble Column
The objective of the study is to experimentally investigate axial dispersion and mass transfer within a bubble column, examining their mutual interrelation\nand their correlation with operational ...
Exploring Bubble Dynamics with VOF Method Simulations: Insights from Two Fundamental Gas-Liquid Flow Case Studies
Harrandt, Václav
2024 - English
The present study focuses on the flow of Taylor bubbles, representing the interaction between the channel wall and the gas phase, and the collision of\na bubble with a vortex ring, serving as a model liquid-gas interaction. Understanding the former case can be essential to prevent the membrane\nfouling or the flow induced corrosion. The dynamics of the latter case is the predictive criterion for whether the initial mother bubble will break up into the daughter bubbles or not2 and this process can therefore be used as an idealized model of turbulent bubble flow.
Keywords:
bubble dynamics; multiphase interaction,; numerical simulation
Available in a digital repository NRGL
Exploring Bubble Dynamics with VOF Method Simulations: Insights from Two Fundamental Gas-Liquid Flow Case Studies
The present study focuses on the flow of Taylor bubbles, representing the interaction between the channel wall and the gas phase, and the collision of\na bubble with a vortex ring, serving as a model ...
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