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Effect of the numerical grid density on the modelling of fluid flow in a stirred tank with a PMT impeller

100%
Story A., Jaworski Z.
Czasopismo Techniczne
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-
PL
The paper present the results of numerical simulations performed for a stirred tank equipped with a PMT type impeller, filled up with a Newtonian fluid. The effects of the grid density and mesh quality and also of the simulation mode on the modelling of fluid flow in a stirred tank were studied. The results are compared with literature data obtained from LDA measurements. It was found that denser numerical grids give more detailed information about generated flow field near the impeller blades. Additionally, better compatibility of predicting and experimental results was obtained in the case of the transient mode simulation, what also demonstrates a significant effect of the angular position of the impeller against baffles on the generated velocity field.
2
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Fluctuations of the non-Newtonian fluid flow in a Kenics static mixer: An experimental study

100%
Peryt-Stawiarska S., Jaworski Z.
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vol. 10
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issue 3
35-37
EN
The measurements for a Kenics static mixer were carried out using Laser Doppler Anemometer (LDA). The test fluid was non-Newtonian solution of CMC, Blanose type 9H4. The velocity data inside the 5th Kenics insert were collected for the axial components at five levels of Reynolds number, Re = 20 ÷ 120. Velocity fluctuations were also analyzed in the frequency domain, after processing them with the help of the Fast Fourier Transform (FFT) procedure. The spectra of fluctuations provided information about level of the fluctuations in the observed range of Reynolds number. The obtained data were then also used to plot the velocity profiles for the fifth insert of the Kenics mixer. It was concluded that in the investigated range of Reynolds numbers (Re = 20 ÷ 120) a strong dependence of the velocity profiles and the flow fluctuations on Reynolds number was observed.
3
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CFD modelling of two-phase liquid-liquid flow in a SMX static mixer

100%
Pianko-Oprych P., Jaworski Z.
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EN
The paper provides an overview of the application of Computational Fluid Dynamics tools for predicting transport processes in two-phase flow in a SMX static mixer. The overview is achieved by taking a brief look at factors: mesh generation, development of sub-models, post-processing including validation and quantitative verification of CFD results with experimental data. Two types of numerical approach were used in the simulations: the Reynolds averaged Navier-Stokes in the steady-state mode with the standard k-??turbulence model and Large Eddy Simulations in the unsteady mode. Both CFD techniques were applied to calculate flow velocities, pressure drop and homogenisation level in a SMX static mixer of the liquid-liquid mixture. The steady state drop size distribution was obtained by implementation procedure containing the population balance equation, where transport equations for the moments of the drop size distribution are solved and the closure problem is overcome by using the Quadrature Method of Moments.
4
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A comparative study of thermodynamic electrolyte models applied to the Solvay soda system

81%
Jaworski Z., Czernuszewicz M., Gralla Ł.
Chemical and Process Engineering
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2011
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vol. 32
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issue 2
135-154
EN
Fast development of computation techniques for electrolyte activities contributed recently to introduction of a few substantial programmes for thermodynamic computing of multiphase systems. The presented study comprises useful information for practical computing using selected thermodynamic models of aqueous electrolyte solutions. Those models enable quantitative description of both phase and ionic equilibria and provide values of activity coefficients. The carried out analysis of individual models involved a comparison of their practical effectiveness features along with problems encountered in evaluation of the coefficients. The authors conclude that for the Solvay soda system the exUNIQUAC model for an in-house code or the MSE model for a commercial one can be used.
5
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Numerical analysis of thermal stresses in a new design of microtubular stack

81%
Pianko-Oprych P., Zinko T., Jaworski Z.
Open Chemistry
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2015
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vol. 13
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issue 1
EN
Microtubular Solid Oxide Fuel Cells (mSOFCs) are one of the most promising and efficient devices that convert chemical energy of fuels into electrical energy. However, mSOFC stacks work at high operating temperature over 650°C, which leads to thermally induced mechanical stresses and in consequence may cause failure of stack components. In order to reduce the local thermal gradients and prevent high stresses in the stack components, it is desirable to study the effect of stack design on its performance. For this purpose a 3D numerical approach was developed to estimate thermal expansion of fuel cell inside an mSOFC stack and to reduce the associated experimental efforts and costs. Initially, a Computational Fluid Dynamics (CFD) model was used to calculate the temperature and species concentration profiles. During the second modeling step temperature profiles were used in the thermo-mechanical model to calculate the thermal stress distribution in the mSOFC stack. The results maximum thermal axial elongation that equals 1.4 mm for the mSOFC stack. The modelled maximum radial elongation was equal to 0.5 mm in the contact areas of the cylindrical housing and manifolds on the fuel inlet side.
6
Content available remote

Cfd Analysis of Heat Transfer in a Microtubular Solid Oxide Fuel Cell Stack

81%
Pianko-Oprych P., Kasilova, E., Jaworski Z.
Chemical and Process Engineering
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2014
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vol. 35
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issue 3
293-304
EN
The aim of this work was to achieve a deeper understanding of the heat transfer in a microtubular Solid Oxide Fuel Cell (mSOFC) stack based on the results obtained by means of a Computational Fluid Dynamics tool. Stack performance predictions were based on simulations for a 16 anodesupported mSOFCs sub-stack, which was a component of the overall stack containing 64 fuel cells. The emphasis of the paper was put on steady-state modelling, which enabled identification of heat transfer between the fuel cells and air flow cooling the stack and estimation of the influence of stack heat losses. Analysis of processes for different heat losses and the impact of the mSOFC reaction heat flux profile on the temperature distribution in the mSOFC stack were carried out. Both radiative and convective heat transfer were taken into account in the analysis. Two different levels of the inlet air velocity and three different values of the heat losses were considered. Good agreement of the CFD model results with experimental data allowed to predict the operation trends, which will be a reliable tool for optimisation of the working setup and ensure sufficient cooling of the mSOFC stack.
7
Content available remote

Quantification of the Radiative and Convective Heat Transfer Processes and their Effect on mSOFC by CFD Modelling

81%
Pianko-Oprych P., Kasilova E., Jaworski Z.
Polish Journal of Chemical Technology
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2014
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vol. 16
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issue 2
51-55
EN
The CFD modelling of heat transfer in a microtubular Solid Oxide Fuel Cell (mSOFC) stack has been presented. Stack performance predictions were based on a 16 anode-supported microtubular SOFCs sub-stack, which is a component of the overall stack containing 64 fuel cells. Both radiative and convective heat transfer were taken into account in the modelling. The heat flux value corresponded to the cell voltage of 0.7 [V]. Two different cases of the inlet air velocity of 2.0 and 8.5 [ms–1] were considered. It was found that radiation accounted for about 20–30 [%] of the total heat flux from the active tube surface, which means that the convective heat transfer predominated over the radiative one.
8
Publication available in full text mode
Content available

PIV measurements of the velocity field of a newtonian fluid in a stirred tank equipped with the PMT type impeller

81%
Story A., Jaworski Z., Simmons M., Nowak E.
Czasopismo Techniczne
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-
PL
The paper presents the results of Particle Image Velocimetry (PIV) measurements of the velocity field of a Newtonian fluid in a mixing tank equipped with a PMT type impeller. The results are presented in the form of the velocity vectors, profiles and maps and compared with available data in the literature for the corresponding system, obtained from Laser Doppler Anemometry (LDA) measurements. A good qualitative agreement of the results was found. In the flow one primary and two secondary circulation loops were observed. The PMT type impeller produced a typical axial-radial circulation of the liquid in the vessel. The value of the circulation flow number, KC, was calculated.
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