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Wyświetlanie 1-7 z 7
Tytuł:
Production and formation modelling of CaCO3 in multiphase reactions – A review
Autorzy:
Gierycz, Paweł
Poświata, Artur
Powiązania:
https://bibliotekanauki.pl/articles/2034048.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CaCO3 production
CaCO3 formation modelling
continues reactors
bubble column reactor
thin film reactor
produkcja CaCO3
modelowanie powstawania CaCO3
reaktor cienkowarstwowy
Opis:
The paper presents different approaches to the proper and accurate production and modelling (multi- phase reaction) of CaCO3 formation in the most popular, different types of reactors, i.e. continuous reactor (STR – stirred tank reactors, MSMPR – mixed suspension, mixed product removal; tube reactor), a bubble column reactor and a thin film reactor. Many different methods of calcium carbonate production and their effect on the various characteristics of the product have been presented and discussed. One of the most important, from the point of view of practical applications, is the morphology and size of the produced particles as well as their agglomerates and size distribution. The size of the obtained CaCO3 particles and their agglomerates can vary from nanometers to micrometers. It depends on many factors but the most important are the conditions calcium carbonate precipitation and then stored. The experimental research was strongly aided by theoretical considerations on the correct description of the process of calcium carbonate precipitation. More than once, the correct modelling of a specific process contributed to the explanation of the phenomena observed during the experiment (i.e. formation of polyforms, intermediate products, etc.). Moreover, different methods and approaches to the accurate description of crystallization processes as well as main CFD problems has been widely reviewed. It can be used as a basic material to formulation and implementation of new, accurate models describing not only multiphase crystallization processes but also any processes taking place in different chemical reactors.
Źródło:
Chemical and Process Engineering; 2021, 42, 1; 15-34
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces
Autorzy:
Jin, J.
Dang, L. X.
Miller, J. D.
Powiązania:
https://bibliotekanauki.pl/articles/109533.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
molecular dynamics simulations (MDS)
film stability
bubble attachment
interfacial water structure
Opis:
Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, the film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge and zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 1; 89-101
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some remarks on attachment of a gas bubble to another phase both immersed in water
Autorzy:
Kowalczuk, P. B.
Drzymala, J.
Powiązania:
https://bibliotekanauki.pl/articles/110908.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
hydrophobicity
aquaoleophobicity
contact angle
liquid film
attachment
Opis:
In this paper the importance of definition of hydrophobicity and aquaoleophilicity in terms of contact angle as well as the properties of water films in flotation and oil agglomeration were briefly presented. It was shown that the hysteresis of contact angle for a considered system depends on the way of measurement and geometry of the system due to the presence of other that excess pressure and capillary forces and buffering properties of the capillary force. It was suggested that, the measured advancing and receding contact angles should be, when possible, recalculated into the Young (rest, equilibrium) contact angle. It was discussed that quartz is not a good model of hydrophilic surface because its contact angle with a gas phase in water is not zero and that a spontaneous attachment between highly hydrophobic materials such as hydrocarbons and Teflon in dynamic system, such as flotation, does not occur.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 1; 147-154
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of viscosity on the shape of an air Taylor bubble in a stagnant liquid under turbulent condition in falling film
Autorzy:
Lertnuwat, B.
Powiązania:
https://bibliotekanauki.pl/articles/265385.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
lepkość
metoda Taylora
turbulencja
Dumitrescu model
viscosity
Taylor bubble
turbulence
Opis:
This work aims to find the influence of the liquid viscosity on the shape of an air Taylor bubble, rising up in a pipe column which contains the liquid under conditions that the liquid is stagnant and the Froude number is approximately equal to 0.35. Five liquid viscosities (from 0.001 to 0.01 Pa · s) were selected for being computationally investigated. An appropriate shape of a Taylor bubble, corresponding to each selected viscosity, was obtained by considering a pressure distribution of the air inside the bubble. Simulation results showed that the Taylor bubble shape would be thicker if the liquid viscosity was decreased. This could be explained by using the theory of the log-law velocity profile.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 67-77
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena wpływu dodatku regranulatu na własności opakowaniowej folii pęcherzykowej
Ewaluation of the regranulate additive impact on the properties of air bubble film package
Autorzy:
Rojek, M.
Szymiczek, M.
Powiązania:
https://bibliotekanauki.pl/articles/278484.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Inżynierii Materiałów Polimerowych i Barwników
Tematy:
folia opakowaniowa
folia pęcherzykowa
folia polietylenowa
regranulat
właściwości reologiczne
właściwości wytrzymałościowe
regranulacja
packaging film
bubble film
polyethylene film
regranulate
rheological properties
strength properties
regranulation
Opis:
W pracy opisano problem zagospodarowania odpadów z folii pęcherzykowej, przez poddanie jej procesowi regranulacji. Badania przeprowadzono na kompozycjach zawierających regranulat oraz mieszaninę polietylenu liniowego małej gęstości (LLDPE) i polietylenu małej gęstości (LDPE). W ramach badań przygotowano sześć kompozycji o różnej zawartości poszczególnych składników, a następnie dokonano oceny wpływu dodatku regranulatu na własności reologiczne oraz wytrzymałościowe. Zmianę własności reologicznych określono na podstawie pomiaru masowego wskaźnika szybkości płynięcia, a wytrzymałościowe przez wyznaczenie wytrzymałości na rozciąganie i wydłużenia względnego oraz ilość uszkodzonych pęcherzy w próbie ściskania.
The paper deals with the problem of waste management of air bubble film by subjecting it to the regranulation process. Research was carried out on compositions comprising of a mixture of a regranulate and a linear low density polyethylene (LLDPE) and low density polyethylene (LDPE). Within the research, six compositions were prepared containing different content of the individual components, and then the impact of the regranulate additive was evaluated on the both the rheological and the mechanical properties. The change in rheological properties was determined by measuring the mass-flow rate, and by determining the tensile strength, elongation and the quantity of bubbles in the sample of damaged compression.
Źródło:
Przetwórstwo Tworzyw; 2014, [R.] 20, nr 1 (157), 1 (157); 82-87
1429-0472
Pojawia się w:
Przetwórstwo Tworzyw
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of dynamic adsorption layer formation on bubble attachment to quartz and mica surfaces in solutions of pure and mixed surface-active substances
Autorzy:
Wiertel-Pochopień, A.
Zawala, J.
Powiązania:
https://bibliotekanauki.pl/articles/109361.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quartz
bubble
mica
dynamic adsorption layer
wetting film
three-phase contact
Opis:
The paper presents systematic studies on influence of state of dynamic adsorption layer (DAL) induced at the rising bubble interface on time-scale of the bubble attachment to quartz and mica surfaces immersed in pure n-cetyl-trimethylammonium bromide (CTAB) and mixed octanol/CTAB solutions of different concentrations. It was found that in the case of pure CTAB solutions, the influence of DAL on time of bubble attachment and the three-phase contact (TPC) formation (tTPC) strongly depends on solution concentration. Generally, two solution concentration regimes were distinguished – low and high - for which different degree of solid surfaces hydrophobization was observed. It was determined that for low concentration regime the solid surface is only slightly hydrophobized while for high regime, hydrophobicity of the solid surface is much higher. Consequently, wetting film rupture for low concentration regime is governed by electrostatic interactions while for high concentration regime significance of these interactions is much smaller. As a result, the DAL influenced the film rupture in these two regimes in a quite different manner. For mixed n-octanol/CTAB solutions it was found that CTAB molecules presence is necessary condition for wetting film destabilization. Moreover, thanks to the developed approach, allowing control of initial adsorption coverage over the bubble surface (independently on concentration), it was proved that constant adsorption degree of CTAB molecules at the bubble surface in the mixture, leads to identical times of the TPC formation.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 4; 1083-1094
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Added mass of rising bubble approaching to solid wall – numerical studies
Autorzy:
Zawala, Jan
Powiązania:
https://bibliotekanauki.pl/articles/1450196.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bubble
collision
added mass
liquid film
deformation
Laplace pressure
simulation
Opis:
The numerical approach for determination of influence of deformation of the gas bubble (radius 0.74 mm) on added mass coefficient in (i) steady-state conditions and (ii) during approach to the horizontal wall, is proposed. It is shown that the bubble deformation can be tuned numerically (within the range 1.06 - 1.88) via proper variations of the Laplace pressure, without changing the bubble radius. Influence of the bubble deformation on its motion parameters is discussed and compared to theoretical predictions regarding the bubble drag coefficient and Reynolds number. Moreover, the approach allowing determination of the added mass of rising bubble, on the basis of variations in fluid kinetic energy, is described. It is shown that calculated added mass variations strongly depends on the interplay between (i) the bubble deformation ratio and (ii) its rising velocity. This effect is especially important for added mass of a gas bubble approaching a solid wall, because it can affect the kinetics of drainage of the separating liquid film formed under dynamic conditions, when Re >> 1.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 6; 41-50
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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