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Determination of thermophysical properties of scale layer on steel at high temperatures
Ondruch, Tomáš ; Votavová, Helena (referee) ; Pohanka, Michal (advisor)
The thesis deals with thermophysical properties of scale layer on steel and their determination at high temperatures. The first part summarizes fundamental characteristics of scales, it is also devoted to principles of heat transfer with emphasis on heat conduction. The following text presents current state of research on scales’ thermophysical properties. Subsequently, the thesis aims to experimental measurement of thermophysical properties by use of laser flash method and conducted measurement is described, as well. The following chapters present a finite-element numerical model of the measurement aparatus and computation technique for determination of scales’ thermophysical properties is explained. The obtained results are compared with available data and sensitivity analysis of selected model parameters is carried out.
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Study of utility properties thermal-reflective insulations in the buildings
Holeček, Dominik ; Skříček, Darek (referee) ; Šťastník, Stanislav (advisor)
The diploma thesis is partly dedicated to energetic efficiency of buildings and describes possibilities how to evaluate energetic efficiency of buildings in the Czech Republic. We also get to know with distribution of thermal insulators by material base and use in construction. There are also mentioned methods how to determine thermal insulations characteristics of heat insulations, so called heat conductivity coefficient. The last and the crucial chapter of theoretic part is dedicated to thermal-reflective insulations. There are mentioned some of the basic characteristics of insulations, material composition and heat transfer mechanism in their structure as well. Practical part describes measurement of thermal resistance of chosen samples of thermal-reflective insulations per measuring device on the principal of Hot Box method. In the next step was determined emissivity of aluminium foils which forms the surface of chosen samples of thermal-reflective insulations. In the end of thesis are defined possibilities of use thermal-reflective insulations in building structures especially in passive and low-energy buildings in climatic conditions of the Czech Republic.
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Study of the behavior of insulating materials in a high humidity environment
Havelka, Jindřich ; Peterková, Jitka (referee) ; Zach, Jiří (advisor)
Extruded polystyrene (XPS) is presented as non-absorbent material and it is applied in building construction with high moisture, such as inverted roof. The reason for that is a very good ratio of thermal and mechanical properties and it is used in moisture-loaded applications due to the closed pore structure and high diffusion resistance factor, which are declared by the manufacturers. Long-term experience and studies show that XPS accumulates moisture during long-term exposure in an environment with high humidity. A long-term water absorption test at full immersion for 84 days has been proposed to better illustrate the trend of increasing water absorption. A total of 6 products from different manufacturers that are recommended for inverted roof application, were tested. All tested XPS products have reached high amount of water absorption. The main goal was to map the real properties of XPS at high humidity loads. It was found that each product showed a different degradation of thermal conductivity at the same volume moisture value. Furthermore, there was found the connection between the surface structure and amount of water absorption. Products with waffle structure had higher humidity than products with a fine structure.
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Impact of injection on mechanical and physical characteristics of mortar
Fridrich, Pavel ; Myslín, Jiří (referee) ; Tomíček,, Oldřich (referee) ; Klečka,, Tomáš (referee) ; Tuza, Karel (advisor)
The increased moisture of the building materials causes the change of its mechanical and physical characteristic. In particular the high amount of loose water in construction shorten the lifetime of the building, is harmful to human beings due to biotic factors and increase the economic expenses of usage of the building. Apart from the costs of rehabilitation the loose water deteriorates the thermal insulative ability (thermal conductivity coefficient ) of perimeter masonry as well. The moisture gets into masonry not only through its deffects but also due to many different reasons. In order to improve the utility value of the buildings we have to deal with the rehabilitation of damp masonry with view to all possible causes. Only the properly working damp proofing ensures the protection against the water leaking from the subfoundation of the building. One of the direct techniques which have undergone rapid progress in last few years is the injection procedure. With use of experimental methods in my dissertation I deal with evaluation of two injection compounds used in Czech Republic and with its impact on the characteristics of the mortar. With the modern hollow bricks (system THERM) it is possible to create horizontal infusion into the lateral mortar grooves in future.
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Study of possibilities of optimalization of properties of alternative thermal insulating materials on natural base
Břicháček, Pavel ; Peterková, Jitka (referee) ; Zach, Jiří (advisor)
The presented work investigates the mechanisms of propagation of heat and moisture in the structure of heat-insulating materials based on natural fibers. The main aim of this work is the experimental verification of theoretical patterns, which are involved in the transport of heat and moisture in fibrous materials, especially the influence of fibers thickness and density of the fibrous materials. To widen outputs of the work were selected different kinds of natural fiber materials of vegetable and animal origin. The results of the work should help to optimize the production processes of natural insulation materials considering their optimal thermal properties. From the data collected are deduced general conclusions to better understanding the behavior of these materials.
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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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Development of ultra lightweight concretes
Popelková, Adéla ; Hubertová,, Michala (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with the technology of production of ultralight concretes using direct lighten cementing compound and at the same time indirect lighten using lightweight aggregate. Further work deals with the choice of suitable raw materials for these concretes. The practical part consists of a proposal of several different recipes, experimental verification and by comparing their properties in a fresh or hardened state.
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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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