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1
Content available Liquid-liquid two phase-system stabilized by tween 40 and 80 surfactants: multiparametric study
Murasiewicz Halina, Illienko Khrystyna
Polish Journal of Chemical Technology
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2024
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Vol. 26, nr 1
51--63
EN
The purpose of this study was to investigate the impact of process parameters such as interfacial tension, type of surfactants, and their concentration on simple oil-in-water dispersion. Explored systems were prepared with 5% liquid paraffin oil and aqueous phase with emulsifiers Tween 40 of concentrations from 0.008325 mM to 0.025 mM and Tween 80 with concentrations ranging from 0.00375 mM to 0.011 mM. All systems were characterized in terms of their density and interfacial tension. In the next step analysis of droplet size distributions and mean droplet diameter was performed. The results showed that the size of paraffin droplets decreased as the concentration of surfactants grew. This trend is accompanied by decrease in the interfacial tension between phases. The correlation between mean drop size and the energy input and physical properties of both liquids was developed. The last step provides scientific evidence for the formulation of stable droplets of liquid paraffin.
2
Content available Gas hold-up analysis in an unsteady stirred vessel by means of infinite series
Frankiewicz Sebastian S., Woziwodzki Szymon
Polish Journal of Chemical Technology
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2023
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Vol. 25, nr 2
30--35
EN
The use of a liquid level sensor made it possible to measure changes in gas hold-up over time in a stirred tank during unsteady mixing. These results were subjected to Fourier time series analysis and a model of gas hold-up changes in time was proposed. It allowed one to determine the model value of gas hold-up, which can be useful for characterizing gas hold-up during unsteady mixing and as a comparison to gas hold-up during steady mixing. The characteristic frequency was also determined, which corresponds to about twice the oscillation frequency. Model gas hold-up values for coalescing and non-coalescing systems were compared. Moreover, the change of the gas hold-up at constant maximum stirrer rotation frequency and variable gas flow rate for different oscillation frequencies was investigated.
3
Content available Study of the effect of geometric shape on the quality of mixing: Examining the effect of length of the baffles
Bouchouicha Malika Seddik, Laidoudi Houssem, Hassouni Souad, Makinde Oluwole Daniel
Archives of Thermodynamics
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2023
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Vol. 44, no 2
69--85
EN
This work is an attempt to study the behaviour of fluid in the mixing vessel with a two-bladed or four-bladed impeller. The working fluid is complex, of a shear-thinning type and the Oswald model is used to describe the fluid viscosity. The study was accomplishedby numerically solving the governing equations of momentum and continuity. These equations were solved for the following range of conditions: 50–1000 for the Reynolds number, 0–0.15 for the baffle length ratio, and the number of impeller blades 2 and 4. The simulations were done for the steady state and laminar regime. The results show that the increase in baffle length (by increasing the ratio baffle length ratio) decreases the fluid velocity in the vessel. Increasing the speed of rotation of the impeller and/or increasing the number of blades improves the mixing process. Also, the length of the baffles does not affect the consumed power.
4
Content available remote The Computational-Fluid-Dynamics study of an unbaffled stirred vessel with eccentrically positioned impeller
Wójtowicz R., Lipin A. A.
Czasopismo Techniczne. Chemia
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2015
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R. 112, z. 1-Ch
99--108
EN
The paper presents the results of CFD simulations of liquid flow in an unbaffled stirred vessel with an eccentrically positioned impeller. The influence of the impeller’s distance from the tank axis (eccentricity) on the generated flow circulation was analyzed. Based on numerical modelling, the flow pattern, vortex formation as well as turbulence parameters in selected stirred vessel zones were determined. Obtained results were presented as vector/contour maps, and iso-surfaces of Q- criterion for identification of vortex cores. Additionally, for each investigated stirred vessel power consumption was calculated.
PL
W pracy przedstawiono wyniki symulacji CFD ruchu cieczy w mieszalniku mechanicznym bez przegród z niecentrycznie usytuowanym mieszadłem. Analizowano wpływ zmian odległości mieszadła od osi aparatu (niecentryczności) na generowaną w mieszalniku cyrkulację. Na podstawie modelowania numerycznego wyznaczono model przepływu cieczy, strefy tworzenia się wirów oraz parametry turbulencji w wybranych obszarach mieszalnika. Uzyskane wyniki przedstawiono w postaci wektorowych i konturowych map rozkładu, do identyfikacji położenia rdzeni wirów wykorzystano powierzchnie stałych wartości Q-kryterium. Dodatkowo w każdym z badanych mieszalników wyznaczono zapotrzebowanie mocy.
5
Content available remote Zastosowanie pozytonowej tomografii emisyjnej i numerycznej mechaniki płynów do badania warunków wytwarzania zawiesin w mieszalniku mechanicznym
Pianko-Oprych P.
Przemysł Chemiczny
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2011
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T. 90, nr 8
1561-1566
6
Content available Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller
Ameur H., Bouzit M., Helmaoui M.
Chemical and Process Engineering
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2011
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Vol. 32, nr 4
351-366
EN
The present work deals with agitation of non-Newtonian fluids in a stirred vessel by Scaba impellers. A commercial CFD package (CFX 12.0) was used to solve the 3D hydrodynamics and to characterise at every point flow patterns especially in the region swept by the impeller. A shear thinning fluid with yield stress was modelled. The influence of agitator speed, impeller location and blade size on the fluid flow and power consumption was investigated. The results obtained are compared with available experimental data and a good agreement is observed. It was found that an increase in blade size is beneficial to enlargement of the well stirred region, but that results in an increased power consumption. A short distance between the impeller and the tank walls limits the flow around the agitator and yields higher power consumption. Thus, the precise middle of the tank is the most appropriate position for this kind of impeller.
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