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Model of the reactor chamber for microwave heating
Kříž, Tomáš ; Fiala, Pavel (referee) ; Kroutilová, Eva (advisor)
The diploma thesis deals with the concept of a high-frequency chamber which serves for desiccation of emulsion consisted of oil and water where the contents of water is over 30% of the emulsion capacity. The high-frequency chamber works on frequency 2,45 GHz. The task was to design a numerical model in which a high-frequency thermic conjugated problem is solved. The design of a high-frequency chamber is made up considering the heat distribution in inhomogeneous environment as well as chemical and physical changes. The proportions of the high-frequency chamber can guarantee the biggest output transmitted from the source to the chamber with the emulsion desiccated and uniform layout of electromagnetic field. These criteria are necessary for smooth heating of the emulsion desiccated. In this diploma thesis, there were several numerical models with various proportions made up. Finally, the one with the shortest time of heating the emulsion in reference to emulsion capacity was chosen.
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Analysis of EMW radiation for sterilization of biotic pests
Danielová, Marie ; Svobodová, Kateřina (referee) ; Holešovský, Jan (advisor)
Biotic pests such as wood-destroying fungi, molds, and wood-destroying insects are not only a problem for old buildings but also for newer buildings. Their occurrence has a negative effect on the physical and mechanical characteristic of building materials. One of the main causes of biotic pests in buildings is moisture. Remediation of objects in terms of moisture and biotic pests is a frequent subject of solution in construction practice. There are many methods used to remove moisture and inactivate biotic pests, and their use depends on the individual requirements of individual objects. In practice, this problem is dealt with by specialized companies using well-known technologies or further participate in their research. One of the methods used for moisture remediation and inactivation of biotic pests is the irradiation of building structures using EMW radiation. Microwave heating used to dry moisture from building materials is one of the most intensive methods for sterilizing biotic pests, and due to its intensity, it is a time and cost-effective method.
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Application of microwave heating for curing of adhesives and composite materials
Wagnerová, Klára ; Urík, Tomáš (referee) ; Klement, Josef (advisor)
This bachelor's thesis concerns the microwave technology and the possibilities for its use in the curing of adhesives and composite materials. The thesis is divided into two main parts. The first part summaries theoretical findings about microwave technology. There is the principle of microwave heating described as well as constructions of microwave devices. Also the possibilities of using this technology for the curing of composite structures are mentioned. The second part of the thesis is devoted to the practical verification of the theoretical assumptions.
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Waste Recycling Possibilities of Rigid PU Foams from the Production of KingSpan CZ
Figalla, Silvestr ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the bachelor thesis evaluates methods and trends of recycling polyurethane materials with the emphasis on rigid polyurethane foams used as thermo isolation building material. The experimental part is focused on glycerol process verification as an alcoholization agent in the regenerative process of polyol, together with perspective microwave heating of reaction mixture. The final part of the work suggests further steps in the development of above mentioned process with the aim of its transforming into technical practice.
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Preparation of methacrylated hydroxybutyrates monomers and polymers
Liška, Marek ; Mgr. Petra Zbořilová, Ph.D (referee) ; Figalla, Silvestr (advisor)
The aim of this work is the study, design, and preparation of methacrylated derivatives of poly(3-hydroxybutyrate) and the subsequent preparation of polymers from the prepared precursors. A total of six compounds were prepared. The prepared compounds include methyl-3-hydroxybutyrate and ethyl-3-hydroxybutyrate prepared by alcoholytic depolymerization with monofunctional alcohol and their methacrylated derivatives. The preparation of ethylene glycol terminated oligomer of 3-hydroxybutyrate prepared via depolymerization using ethylene glycol in two ways is also an essential part of the work. The first way involves depolymerization using conventional heating and the second one explores the preparation of a series of oligomers with different molecular weights using microwave heating. Methacrylated derivatives of the prepared oligomers were also prepared. The prepared compounds and their actual preparation are characterized using multiple analytical methods including VPO, NMR, GPC, FT-IR, LC-MS, and DSC. A series of polymers were obtained from the prepared compounds by radical polymerization using purple light (with wavelength 405 nm) as the energy source. The prepared polymer networks were characterized by DSC and their tensile strengths were tested.
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Využití mikrovlnné plastifikace dřeva při výrobě ohýbaných nábytkových dílců
Nováčková, Kateřina
This bachelor thesis is dealing with microwave plasticization for wood shaping and its potential utilization in furniture industry. European beech (Fagus sylvatica L.) specimens of dimensions 20 × 20 × 300 mm were sorted into 8 groups (each group consisted 15 specimens). Reference specimens (Ref1) were tested as oven-dried at room temperature, furthermore reference specimens (Ref2) were tested as oven-dried at 80 °C and last reference group (Ref3) was conditioned to fiber saturation point (FSP). Specimens of conventional, steam plasticization (Vp) were conditioned to FSP and heated at 100 °C for 1 hour. Microwave plasticization was carried out at 1,5 and 3,5 kW using continuous laboratory MW device All MW specimens were soaked in water in order to reach approx. 60 % of MC.Output moisture content (MC) of MW treated specimens was 20 % (MW1), 30 % (MW2, MW4) and 40 % (MW3). Moreover, additional specimens of dimensions 30 × 30 × 450 mm were used to up-scale its possibilities of use. These specimens were sorted into 2 groups (Ref and MW), each group consited 20 specimens. Effect of plasticization was measured by means of static 3-point bending test. Plasticity of wood was evaluated by modulus of elasticity (MOE), modulus of rupture (MOR) and deflection. Results of reference specimens confirmed influence of temperature and moisture content on MOE and MOR. Influence of moisture content (0 % and FSP) was found to be more significant and 65 % decrease of strength MOR and 40 % of MOE is reported. Steam plasticization, as a conventionally used method for shaping, led to increase of plasticity (decrease of MOE about 65 %) and deflection (70 %) when compared to Ref1. Significantly higher deflection (up to 1,5 mm) and increase of plasticity (MOE decreased about 72 %) was found for specimens plasticized by MW at 1,5 kW and 3,5 kW from initial moisture 60 % to output moisture 30 %. Based on results, it can be stated that microwave technology have similar effects on wood plasticity, when compared to conventional method wood plasticization – steaming. Results of present thesis confirmed high potential of MW plasticization for wood shaping. Reduction of time and safe energy might be considered as a great advantage for furniture production. Futher studies should be done in future in order to reveal effect of MW on structural changes, eventually to optimize process for specific shapes.
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Model of the reactor chamber for microwave heating
Kříž, Tomáš ; Fiala, Pavel (referee) ; Kroutilová, Eva (advisor)
The diploma thesis deals with the concept of a high-frequency chamber which serves for desiccation of emulsion consisted of oil and water where the contents of water is over 30% of the emulsion capacity. The high-frequency chamber works on frequency 2,45 GHz. The task was to design a numerical model in which a high-frequency thermic conjugated problem is solved. The design of a high-frequency chamber is made up considering the heat distribution in inhomogeneous environment as well as chemical and physical changes. The proportions of the high-frequency chamber can guarantee the biggest output transmitted from the source to the chamber with the emulsion desiccated and uniform layout of electromagnetic field. These criteria are necessary for smooth heating of the emulsion desiccated. In this diploma thesis, there were several numerical models with various proportions made up. Finally, the one with the shortest time of heating the emulsion in reference to emulsion capacity was chosen.
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Optimization of Microwave Glycerolysis of Crosslinked Rigid PU Foams for Using Recyclate in Production
Figalla, Silvestr ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part summarizes the chemical recycling processes of polyurethane and polyisocyanurate insulation foams and methods of polyols preparation from their alcoholysates. Emphasis is placed on the use of microwave heating during depolymerization, as a perspective energy source for chemolysis processes. The practical part is focused on optimization of recyclates preparation derived from polyisocyanurate foams and polyethylene terephthalate by microwave enhanced glycerolysis. Recyclates obtained were verified for their workability and applicability in blends with virgin polyols in polyisocyanurate foam manufacture process.
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Application of microwave heating for curing of adhesives and composite materials
Wagnerová, Klára ; Urík, Tomáš (referee) ; Klement, Josef (advisor)
This bachelor's thesis concerns the microwave technology and the possibilities for its use in the curing of adhesives and composite materials. The thesis is divided into two main parts. The first part summaries theoretical findings about microwave technology. There is the principle of microwave heating described as well as constructions of microwave devices. Also the possibilities of using this technology for the curing of composite structures are mentioned. The second part of the thesis is devoted to the practical verification of the theoretical assumptions.
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Waste Recycling Possibilities of Rigid PU Foams from the Production of KingSpan CZ
Figalla, Silvestr ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the bachelor thesis evaluates methods and trends of recycling polyurethane materials with the emphasis on rigid polyurethane foams used as thermo isolation building material. The experimental part is focused on glycerol process verification as an alcoholization agent in the regenerative process of polyol, together with perspective microwave heating of reaction mixture. The final part of the work suggests further steps in the development of above mentioned process with the aim of its transforming into technical practice.
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