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Computational modeling of heat transfer problems in porous structures
Mráz, Kryštof ; Karimi-Sibaki, Ebrahim (referee) ; Boháček, Jan (advisor)
Vrstva okují, skládající se z oxidů železa, která se tvoří na povrchu oceli při jejím tepelném zpracování, má velký vliv na tepelné metalurgické procesy. Tepelná vodivost okují je jeden z klíčových parametrů pro numerické modelování procesů odkujování a chlazení oceli. Tato vodivost je nicméně silně ovlivňována porézní strukturou okují a žádná všeobecně uznávaná materiálová data nejsou v současnosti dostupná. Cílem této práce bylo provést stacionární tepelnou analýzu za účelem stanovení tepelné vodivosti vrstvy okují. Byl vytvořen podrobný 3D MKP model vrstvy okují založený na datech získaných pomocí CT skenování. Je popsáno získání CT obrazu a jeho zpracování. Využity byly dva různé způsoby segmentace. Pravidelná krychlová výpočetní síť byla vytvořena přímo z voxelové matice zpracovaného CT obrazu. Výsledné hodnoty tepelné vodivosti získané z provedené MKP analýzy byly téměř identické pro obě metody segmentace, což prokazuje jejich vhodnost. Výsledná tepelná vodivost okují může být dále využita jako materiálová charakteristika v numerických modelech tepelného zpracování oceli
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MEMS microhotplate platform for chemical sensors
Vančík, Silvester ; Svatoš, Vojtěch (referee) ; Prášek, Jan (advisor)
This master’s thesis deals with design and fabrication of MEMS microhotplate platform for chemical gas sensors. The theoretical part describes MEMS, sensors and processes and technologies needed for fabrication of micro hotplate. The practical part includes simulations, masks and step by step microhotplate fabrication. Fabricated heating membrane was characterized and compared to theoretical values from simulations and to similar devices presented in literature.
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The thermal conductivity of non-standard materials for HVAC
Běťák, Karel ; Rubinová, Olga (referee) ; Uher, Pavel (advisor)
The thesis is focused on the determination of the thermal conductivity coefficient on the group of thermoplastics used for 3D printing (PLA, ABS, PETG). The thesis describes the materials used for 3D printing and the design of air conditioning for the grocery store. A stationary method was used for the solution. The heat flux passing through the sample was measured and the thermal conductivity coefficient was calculated. By the chosen method, we determined the coefficient is = 0,11-0,13 W/(m·K). Comparison with the available results of other methods and authors has shown that the resulting coefficient is lower. Based on the data, it is possible to compare the thermal properties of 3D printing materials.
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Wooden buildings using natural thermal and acoustic insulation
Ambrožová, Elena ; Spáčilová, Jitka (referee) ; Myslín,, Jiří (referee) ; Solař,, Jaroslav (referee) ; Hirš, Jiří (referee) ; Spáčil, Miroslav (advisor)
Dissertation deals with the technical parameters of natural thermal insulation. In addition, there is a global trend in the construction of reducing energy consumption for heating, air conditioning, or with operating facilities in buildings and the use of perspective and efficient building materials with a negligible negative impact on the environment. Therefore, the attention not only professionals are increasingly turning to alternative materials, such as natural insulation, the material can be drawn from local sources and whose production is energy-saving and leaving a small ecological footprint. As part of the doctoral thesis were tested short term water absorption, measurements were made of the thermal conductivity and its change after the test short term water absorption. Was determined dependence of thermal conductivity on humidity and heat resistance was determined. Moreover a natural insulation applications in building construction with a comparison of the various technical parameters and environmental footprint. At the conclusion was made by acoustic insulation in timber construction and price analysis.
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Thermoproperties of foundry moulds in dependence on different used foundry sands
Šuráň, Jiří ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
The project elaborated in frame of engineering studies is submitting the study of thermal properties of holding mixtures using different types of sand. Were tested a total of 5 sands: zirkon, ŠH22, chromite, olivine and dunite. Molding compounds were tested for thermal capacity, thermal conductivity and heat accumulation. The highest heat capacity was achieved in dunite sand. The largest heat accumulation had mixture with chromite sand and the best thermal conductivity was found in a mixture with olivine sand.
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Energy Auditing of Building
Sýkorová, Iva ; Koňařík, Marcel (referee) ; Horák, Petr (advisor)
Master´s thesis solves problematic of energy evaluation of residential building in Kyjov. The theoretical part analyzes the legislative requirements, the practical part includes energy audit of brick residential building with 9 apartments for 18 inhabitants.
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Research and Development of Innovative Uranium Nuclear Fuel Matrices
Hrbáček, Tomáš ; Šťastný, Ondřej (referee) ; Katovský, Karel (advisor)
The bachelor thesis is focused on the issue of nuclear fuel used for nuclear reactors. It is dedicated to research of current trends in nuclear pellets. The qualitative parameters of nuclear fuels are described here, predominanly thermal conductivity and density of nuclear fuel. A special chaper of this thesis is devoted to the simulation and fuel additives during burnout. The final part of the bachelor thesis is dedicated to a specific design of material for a test research pellet.
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Investment casting waxes and measurements of their properties with regard to simulation software
Bochníček, Štěpán ; Mikulka, Vít (referee) ; Kosour, Vojtěch (advisor)
Today, the use of simulations is increasing in order to reduce cost and complexity of production and also to prevent product defects. For this purpose, we use simulation programs, such as ProCAST. This program is designed for simulation of casting parts. In my bachelor thesis I focused on the methods of casting lost wax, where the model is made of wax mixture. In each simulation we have to obtain and specify the properties of the material to casting. I described these properties and methods of measurement in this bachelor thesis.
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Identification of Thermal Conductivity and Thermal Capacity of Building Materials by the "Hot Wire Method"
Průša, David ; Čermák,, Jan (referee) ; Šťastník, Stanislav (advisor)
This aim of task deals with study of heat dissipation mechanisms and the description of physical phenomena, which is accompanied by non-stationary measurement of thermal characteristics by the method "hot-wire method". In particular, we observe the coefficient of thermal conductivity and its dependence on various variables such as the temperature of the measured sample, its moisture state, the volume of the sample and its porosity. The above mentioned findings are used for the invention of the measuring device of a nonstationary gauge, which is based on regular heating and is dedicated to measuring the thermal conductivity coefficient and the heat capacity by the "hot-wire method" method. In the last part of the thesis is verified functionality of the proposed measuring device, the suitability of the created algorithm for the processing of the measured data and the evaluation of the results was verified. The reproducibility of the measurements was verified and the measured results were compared with the measurement methods, which are commonly used. the influence of humidity on the coefficient of thermal conductivity.
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