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Low-Cost Filtration Barriers for Ultrafine Particles Separation
Kejík, Pavel ; Fekete, Roman (oponent) ; Lapčík, Ĺubomír (oponent) ; Svěrák, Tomáš (vedoucí práce)
A lot of applications use inorganic filtering media based on materials that use primary resources and their production is energy-intensive and thus costly and environmentally harmful. The aim of this study is to verify whether alkali-activated materials based on secondary resources, namely blast furnace slag (BFS) and fly ash (FA), can be used to produce porous media which could possibly replace ceramic and other inorganic filters. The research question was addressed using an experimental design based on an in-house developed MATLAB calculation scheme for composition mixtures based on the most important oxide ratios in the input raw materials. This way, the greatest control of the variable composition of the inputs was ensured. In addition, the work is more relevant in general because this computational tool takes the basic oxide composition of the resources into account, so the results can be generalized. The author also designed a pure one solid component mixture series for a comparison and better characterization of the effects of composition changes on the resulting product properties. The findings show that the strength of the 24-hour, 70 °C cured materials can exceed 7.6 MPa under a four point bending tensile test (in accordance with ČSN EN 12390 5), but to achieve a good porosity, the strength is always decreased. In the final composition slightly above 6.3 MPa was achieved. In general, the results show that the SiO2/Al2O3 ratio and the amount of alkali activator affect the strength the most. Pure BFS-based mixtures show more than twice the strength of the pure FA-based samples within the given compositions used for the experiments. The fineness of the pores achieved using fractionated raw materials (particle sizes in the range of tens to slightly over a hundred microns) is in the order of tenths to units of microns in most cases and approximately 0.2 microns in the final composition. The total porosity of the pressed bodies is closely under 40% which compared to the unclassified resource based materials, is nearly twice that much. Pure BFS-based samples show lower total porosities than the FA-based samples, apparently due to their entirely different particle morphology – irregularly angular in BFS and round in FA. The efflorescence phenomenon was mostly observed on FA-based materials. Energy-dispersive spectrometry (EDS) confirmed sodium hydroxide crystals undergoing gradual carbonation by atmospheric CO2. Permeability testing required asymmetrical barriers preparation due to the very fine porosity of the material. The asymmetrical barriers achieved water permeability of 138 L/h.m2.bar and air permeability of 1320 L/h.m2.bar.
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Limit Modes of Particulate Materials Classifiers
Adamčík, Martin ; Štěpánek, František (oponent) ; Fekete, Roman (oponent) ; Svěrák, Tomáš (vedoucí práce)
With material science demands on ever smaller particle sizes, new approaches and effective methods of their classification are needed. Turbulent flow field patterns and particle trajectories inside of a dynamic air classifier are investigated. Increasing computing power together with new turbulence models and approaches to simulate complex fully turbulent problems by solving Navier-Stokes equations allows studying and capturing smaller flow structures and properties more accurately. Particles below 10 microns are more susceptible to smaller local vortexes and particle fates are therefore more dependent on these local structures. Area of focus are the conditions required for classification of particles with sizes below 10 microns as this size is at the limit of air classification method possibilities. CFD software and the latest knowledge in turbulence modelling are used to numerically simulate flow field inside a dynamic air classifier. Effects of varying operating parameters on flow patterns and discrete phase classification outputs are investigated. Experimental verification of the simulated flow fields includes advanced imaging method (PIV) measurement of flow velocity and is used to visualize flow field structures in the classifier rotor blade passageway region. Predicted particle trajectories and their fates are experimentally verified by classification trials carried out on dynamic air classifier and the particle distribution curves are established by laser diffraction method. Tromp curves and efficiency of classification process are studied.
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Vytváření kapalinové clony pro absorpci plynných exhalací
Krištof, Ondřej ; Fekete, Roman (oponent) ; Lapčík,, Lubomír (oponent) ; Svěrák, Tomáš (vedoucí práce)
Disertační práce se zabývá aplikací absorpčních metod pro separaci plynných polutantů ze znečištěných plynných směsí s využitím poloprovozního skrápěcího zařízení scrubber. Míra efektivnosti odstranění plynných polutantů byla stanovena na základě hydrodynamické distribuce tekutin ve vnitřním prostoru skrápěcí komory. Byly vykonány experimentální práce vedoucí k charakterizaci spirálové trysky TF-28 150, která byla použita k distribuci absopční kapaliny. Konkrétně byl vyšetřen dopadový vzor kapalinové clony produkovaný tryskou pomocí intruzivních metod, byly stanoveny efektivní úhly rozstřiku kapalinových clon, rozpadové režimy primární a sekundární atomizace a byla stanovena velikost kapek a rychlost kapaliny pomocí neintruzivních optických metod. Taktéž byly realizovány numerické simulace proudění modelové plynné fáze vnitřním prostorem skrápěcí hlavy a rozstřik kapaliny přes spirálovou trysku. Soubor získaných poznatků lze uplatnit při definování styčné mezifázové plochy a společně určení koeficientu celkového prostupu hmoty tak definovat celkovou kinetiku chemisorpce pro danou kombinaci absorbent absorbát.
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Vytváření kapalinové clony pro absorpci plynných exhalací
Krištof, Ondřej ; Fekete, Roman (oponent) ; Lapčík,, Lubomír (oponent) ; Svěrák, Tomáš (vedoucí práce)
Disertační práce se zabývá aplikací absorpčních metod pro separaci plynných polutantů ze znečištěných plynných směsí s využitím poloprovozního skrápěcího zařízení scrubber. Míra efektivnosti odstranění plynných polutantů byla stanovena na základě hydrodynamické distribuce tekutin ve vnitřním prostoru skrápěcí komory. Byly vykonány experimentální práce vedoucí k charakterizaci spirálové trysky TF-28 150, která byla použita k distribuci absopční kapaliny. Konkrétně byl vyšetřen dopadový vzor kapalinové clony produkovaný tryskou pomocí intruzivních metod, byly stanoveny efektivní úhly rozstřiku kapalinových clon, rozpadové režimy primární a sekundární atomizace a byla stanovena velikost kapek a rychlost kapaliny pomocí neintruzivních optických metod. Taktéž byly realizovány numerické simulace proudění modelové plynné fáze vnitřním prostorem skrápěcí hlavy a rozstřik kapaliny přes spirálovou trysku. Soubor získaných poznatků lze uplatnit při definování styčné mezifázové plochy a společně určení koeficientu celkového prostupu hmoty tak definovat celkovou kinetiku chemisorpce pro danou kombinaci absorbent absorbát.
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Low-Cost Filtration Barriers for Ultrafine Particles Separation
Kejík, Pavel ; Fekete, Roman (oponent) ; Lapčík, Ĺubomír (oponent) ; Svěrák, Tomáš (vedoucí práce)
A lot of applications use inorganic filtering media based on materials that use primary resources and their production is energy-intensive and thus costly and environmentally harmful. The aim of this study is to verify whether alkali-activated materials based on secondary resources, namely blast furnace slag (BFS) and fly ash (FA), can be used to produce porous media which could possibly replace ceramic and other inorganic filters. The research question was addressed using an experimental design based on an in-house developed MATLAB calculation scheme for composition mixtures based on the most important oxide ratios in the input raw materials. This way, the greatest control of the variable composition of the inputs was ensured. In addition, the work is more relevant in general because this computational tool takes the basic oxide composition of the resources into account, so the results can be generalized. The author also designed a pure one solid component mixture series for a comparison and better characterization of the effects of composition changes on the resulting product properties. The findings show that the strength of the 24-hour, 70 °C cured materials can exceed 7.6 MPa under a four point bending tensile test (in accordance with ČSN EN 12390 5), but to achieve a good porosity, the strength is always decreased. In the final composition slightly above 6.3 MPa was achieved. In general, the results show that the SiO2/Al2O3 ratio and the amount of alkali activator affect the strength the most. Pure BFS-based mixtures show more than twice the strength of the pure FA-based samples within the given compositions used for the experiments. The fineness of the pores achieved using fractionated raw materials (particle sizes in the range of tens to slightly over a hundred microns) is in the order of tenths to units of microns in most cases and approximately 0.2 microns in the final composition. The total porosity of the pressed bodies is closely under 40% which compared to the unclassified resource based materials, is nearly twice that much. Pure BFS-based samples show lower total porosities than the FA-based samples, apparently due to their entirely different particle morphology – irregularly angular in BFS and round in FA. The efflorescence phenomenon was mostly observed on FA-based materials. Energy-dispersive spectrometry (EDS) confirmed sodium hydroxide crystals undergoing gradual carbonation by atmospheric CO2. Permeability testing required asymmetrical barriers preparation due to the very fine porosity of the material. The asymmetrical barriers achieved water permeability of 138 L/h.m2.bar and air permeability of 1320 L/h.m2.bar.
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Limit Modes of Particulate Materials Classifiers
Adamčík, Martin ; Štěpánek, František (oponent) ; Fekete, Roman (oponent) ; Svěrák, Tomáš (vedoucí práce)
With material science demands on ever smaller particle sizes, new approaches and effective methods of their classification are needed. Turbulent flow field patterns and particle trajectories inside of a dynamic air classifier are investigated. Increasing computing power together with new turbulence models and approaches to simulate complex fully turbulent problems by solving Navier-Stokes equations allows studying and capturing smaller flow structures and properties more accurately. Particles below 10 microns are more susceptible to smaller local vortexes and particle fates are therefore more dependent on these local structures. Area of focus are the conditions required for classification of particles with sizes below 10 microns as this size is at the limit of air classification method possibilities. CFD software and the latest knowledge in turbulence modelling are used to numerically simulate flow field inside a dynamic air classifier. Effects of varying operating parameters on flow patterns and discrete phase classification outputs are investigated. Experimental verification of the simulated flow fields includes advanced imaging method (PIV) measurement of flow velocity and is used to visualize flow field structures in the classifier rotor blade passageway region. Predicted particle trajectories and their fates are experimentally verified by classification trials carried out on dynamic air classifier and the particle distribution curves are established by laser diffraction method. Tromp curves and efficiency of classification process are studied.
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