|
|
Computational simulation of the compression test of the open cell metal foam
Homola, Václav ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
The thesis presents computational simulation of compression test of a nickel foam and the 3D reconstruction of micro-CT images was utilized to generate the foam’s model of geometry. Explicit FEM is used to simulate compression test using software tool LS-DYNA and the stress–deformation curve is obtained together with deformed model’s mesh used for subsequent analysis. Sensitivity analyses were performed to configure the model and ensure best fit with values obtained during real-life experiment. The ANSYS Classic environment was then used to simulate tensile test of the foam compressed to various thicknesses. The tensile moduli in three mutually perpendicular directions of nickel foam were computed and the results were compared to experimental values as well. The results of tensile test simulation revealed considerable anisotropy of the foam’s elastic behavior. It can be said that the measured experimental data correspond very well with the elastic properties obtained from simulation up to certain level of compression. Analysis of the relationship between the element size and tensile moduli showed a significant difference between fine and coarse mesh. The optimal level of discretization and the overall model configuration ensuring high level of accuracy is proposed in this thesis.
|
|
| |
|
|
Synthesis of novel zeolite materials and their application in catalysis
Veselý, Ondřej ; Přech, Jan (advisor) ; Zima, Vítězslav (referee) ; Hronec, Mlan (referee)
Zeolites are crystalline microporous tectosilicates with acidic properties. The pore sizes of molecular dimensions restrict molecules from entering/exiting the pores based on the molecule size and geometry, or formation of certain (bulky) transition states within the pores. Accordingly, zeolites have become vital industrial catalysts, adsorbents and ion-exchangers. Zeolites are commonly synthesised by hydrothermal crystallization. However, this method provides only limited control over their crystal structure, morphology, or location of active sites within the framework. Some of these limitations can be overcome using an alternative synthetic method; the Assembly-Disassembly-Organisation- Reassembly (ADOR). The ADOR transforms a parent (germanosilicate) zeolite into a layered precursor and subsequently uses the layers as building blocks for a new zeolite framework. We aimed to develop methodology to control the crystal morphology of germanosilicate zeolite UTL (Assembly), determine the mechanism of the UTL hydrolysis (Disassembly), and to reconstruct the parent UTL zeolite from the ICP-1P layered material (Organisation and Reassembly) since the traditional ADOR yields zeolites of smaller channel size but the parent UTL. We found the UTL crystal morphology progressively varies the Si/Ge molar ratio...
|
|
|
Computational simulation of the compression test of the open cell metal foam
Homola, Václav ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
The thesis presents computational simulation of compression test of a nickel foam and the 3D reconstruction of micro-CT images was utilized to generate the foam’s model of geometry. Explicit FEM is used to simulate compression test using software tool LS-DYNA and the stress–deformation curve is obtained together with deformed model’s mesh used for subsequent analysis. Sensitivity analyses were performed to configure the model and ensure best fit with values obtained during real-life experiment. The ANSYS Classic environment was then used to simulate tensile test of the foam compressed to various thicknesses. The tensile moduli in three mutually perpendicular directions of nickel foam were computed and the results were compared to experimental values as well. The results of tensile test simulation revealed considerable anisotropy of the foam’s elastic behavior. It can be said that the measured experimental data correspond very well with the elastic properties obtained from simulation up to certain level of compression. Analysis of the relationship between the element size and tensile moduli showed a significant difference between fine and coarse mesh. The optimal level of discretization and the overall model configuration ensuring high level of accuracy is proposed in this thesis.
|
|
|
Adsorption study of waste materials as potential adsorbents for pollutant removal and storage
Řimnáčová, Daniela ; Vorokhta, Maryna ; Vöröš, Dominik ; Borecká, Lenka ; Bičáková, Olga
The study shows how changing the experimental conditions during carbonization of a waste material such as sewage sludge influences textural properties and the CO2adsorption capacity of final carbonized productsin their potential use for removaland storage of pollutantssuch as carbon dioxide. The CO2adsorption measurements were done with gravimetric and manometric sorption devices in a wide range of pressures and temperatures. Further, CO2adsorption capacities of other materialssuch as activated carbon prepared from black carbon and a Czech Silurian shalewere compared toadsorption capacities of the studied carbonized sewage sludge. These two compared materials were chosen according to their compositionsand porosity.The porosityof the studied materials was determined from the N2sorption isotherms and measurements of their skeletal density with He.The adsorption capacity depended on the ratio of micropores and mesopores in the carbonized sewage sludge, because CO2fillsmicropores and mesopores at lowand highpressures, respectively, and was decreasing with the temperature increase atconstant pressure.The adsorption capacity of the carbonized sewage sludgewas increased by increase inthe carbonization temperature.The obtained adsorption capacities showed that the carbonization of sewage sludge can lead to preparation of perspective adsorbents for CO2capture and storage.
|
|
|
The preparation of porous materials for radionuclide capture
Bajzíková, Anna ; Smrček, Stanislav (advisor) ; Hrubý, Martin (referee)
Title: The Preparation of Porous Materials for Radionuclide Capture Author: Bc. Anna Bajzíková Curriculum: Teaching of Chemistry and Biology for Secondary Schools Type of thesis: Master's Department: Department of Teaching and Didactics of Chemistry, Faculty of Science, Charles University in Prague Elaborated: Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Psysical Engineering, Czech Technical University in Prague Advisor: Doc. Ing. Stanislav Smrček, CSc. Consultant: RNDr. Ján Kozempel, Ph.D. Abstract: The use of radionuclides is still increasing and with it also increases the amount of radioactive waste and this waste have to be processed. This thesis is focused on the preparation, characterization and testing of porous materials which could be used for the process of this waste. There were prepared and characterized materials based on silica and zirkonia with a modified surface. For the modification were used styren with divinilbenzene, polyacrilonitrile and diglycolamides at different configurations of these materials. Furthermore, there were prepared materials based on hydroxyapatite and its modifications. Prepared sorbents were tested for radionuclide capture - flow through the column and also in the static experiments. The capture of 227Ac and its daughter's radionuclides...
|
|
|
The preparation of porous materials for radionuclide capture
Bajzíková, Anna ; Smrček, Stanislav (advisor) ; Čuba, Václav (referee)
This thesis is focused on the preparation of porous materials which may be usable for radionuclide uptake. These characteristics can be found at nanoporous materials (size of pores 1 - 100 nm) or at polymers. Nanoporous metal oxides and silica gel with styrene-divinylbenzene-TODGA modified surface were prepared and characterized for this purposes. All new prepared substances were tested for the efficiency of radionuclides capture. These measurements were done in Ústav jaderného výzkumu in Řež or in our laboratory.
|
|
| |
|
| |
|
| |
guest ::
