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Thermal Losses of the Biomass Boiler
Suchánková, Lenka ; Milčák, Pavel (referee) ; Kracík, Petr (advisor)
The bachelor thesis focuses on the heat loss of the solid fuel boiler, especially on the loss of heat conduction and transfer to the surroundings. In order to minimalize thermal leaks through the boiler walls, materials with good isolation capabilities must be selected when designing. In Microsoft Excel, a universal mathematical model was created to calculate the heat flux flowing through the flat wall of the boiler, from which temperatures can be obtained on the inside of the wall. The work describes the calculation method on which the model is based and its correctness is verified on an experiment based on sensing of temperature fields of wall sur-faces of equipment burning biomass by thermal camera. The model can be used for a wall with up to 9 layers of material, where the wall can be cooled (heat loss) by air and water.
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Acceleration of numerical computation of heat conduction in solids in inverse tasks
Ondruch, Tomáš ; Komínek, Jan (referee) ; Pohanka, Michal (advisor)
The master's thesis deals with possible ways of accelerating numerical computations, which are present in problems related to heat conduction in solids. The thesis summarizes basic characteristics of heat transfer phenomena with emphasis on heat conduction. Theoretical principles of control volume method are utilized to convert a direct heat conduction problem into a sparse linear system. Relevant fundamentals from the field of inverse heat conduction problems are presented with reference to intensive computations of direct problems of such kind. Numerical methods which are well-suited to find a solution of direct heat conduction problems are described. Remarks on practical implementation of time-efficient computations are made in relation with a two-dimensional heat conduction model. The results are compared and discussed with respect to obtained computational time for several tested methods.
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Heating of flat house
Zajíček, Václav ; Vendlová, Lucie (referee) ; Topič, Jan (advisor)
The thesis is composed of three parts - theoretical, computational and a project part. The theoretical part deals with heat sharing through conduction, flow and radiation. The computational part is focused on the overall calculation of the heating system to operate smoothly and reliably. Three gas condensing boilers are designed as a source of heat. The heating of the water is solved as a reservoir. It's source of heat is one gas condensation boiler. The project part contains a technical report and the project documentation on the stage of the implementation dossier.
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Výpočet tepelných ztrát obvodovým pláštěm dřevostavby a teplotního pole ve vybraných konstrukčních detailech
Pokora, Radek
This diploma thesis clarifies a description of thermal field in a construction of wooden building and deals with heat loss issue in an envelope of a building in specificed constructions detailes. You can find in this thesis description of thermal diffusivity in buildings constructions. The task is to create 3-D models of selected construction details of selected wooden building. In those detailes, based on finite element method is created thermal field and thermal flux. And the calculation of heat loss in those construction details. A family house and a house envelope are designed by myself and simulations are made on that family house. I needed to know a boundary settings and heat transfer temperature gradient. The important result is what is the value of heat loss. Then I need to know why and what can I do to fix problém points. There are written stacionary calculations in selected detailes in the thesis. In the end is an evaluation of designed house envelope heat loss. Problem detailes are showed also.
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Design of optimal parameters of multilayer ceramic protective coating for high temperature applications
Dohnalík, Petr ; Hrstka, Miroslav (referee) ; Ševeček, Oldřich (advisor)
The main objective of this work was to design a suitable composition of a protective coatings, made of several different layers of specific materials - with respect to residual stress, induced due to a mismatch in thermal expansion coefficients of each layer. Protective coating in this work means both the thermal and the environmental barrier. These coatings protect components against high temperatures and harsh environment. In this work, necessary theoretical background in the field of the thermal and environmental barrier coatings is introduced. There are mentioned some basic design approaches, commonly used materials and processing methods for the coating structure. The literature review gives an overview of modeling of such coated structures, in particular it is devoted to the thermal barrier coatings deposited by air plasma spray process. The next chapter closely describes classical laminate theory used for calculation of residual stresses in the coating. One of the assumptions of this theory is homogenous temperature field through the coating’s thickness. However, in this work was revealed a way to extend the classical lamination theory of such cases, in which the temperatures vary along the thickness of the coating. In the practical part, the analytical model was used for designing suitable properties of some coatings, which were consists of two, three and four layers. The calculations were performed both for constant temperature and for the temperature gradient. All results obtained from analytical approach were verified by numerical calculations.
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A Stefan problem of heat conduction with phase change and its exact solution
Kesler, René ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
This bachelor's thesis deals with analytical solutions of heat conduction problems with phase change which are known as classical Stefan problems. At the beginning a differential equation of heat conduction is derived and a mathematical model of Stefan problem is formed. The greatest attention is paid to the derivation of analytical solutions for cases in which these solutions are obtainable. The MATLAB environment was chosen for implementation of the obtained solutions. The thesis also includes a description of the program and its graphical interface in MATLAB. The applicability of the program is demonstrated in several phase change problems.
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Thermal Contact Resistance Under High Temperature
Kvapil, Jiří ; Návrat, Tomáš (referee) ; Brestovič, Tomáš (referee) ; Horský, Jaroslav (advisor)
Nowadays numerical simulations are used to optimize manufacturing process. These numerical simulations need a large amount of input parameters and some of these parameters have not been sufficiently described. One of this parameter is thermal contact resistance, which is not sufficiently described for high temperatures and high contact pressure. This work describes experimental measuring of thermal contact resistance and how to determine thermal contact conductance which can be used as a boundary condition for numerical simulations. An Experimental device was built in Heat Transfer and Fluid Flow Laboratory, part of Brno University of Technology, and can be used for measuring thermal contact conductance in various conditions, such as contact pressure, initial temperatures of bodies in contact, type of material, surface roughness, presence of scales on the contact surface. Bodies in contact are marked as a sensor and a sample, both are embedded with thermocouples. The temperature history of bodies during an experiment is measured by thermocouples and then used to estimate time dependent values of thermal contact conductance by an inverse heat conduction calculation. Results are summarized and the dependence of thermal contact conductance in various conditions is described.
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Method for the solution of conduction heat transfer in Phase change material with nanoparticles
Kopečková, Barbora ; Knotek, Stanislav (referee) ; Jícha, Miroslav (advisor)
This master thesis deals with problematic of the heat convection in phase change materials (PCM) and PCM with nanoparticles. The derivation of stationary and non-stationary equations for 1D, 2D and 3D heat convection are described in detail. The finite element volume method is used for solution to these equations, of which principle is described carefully. The aim of this thesis is model development for 2D solution to temperature distribution at heat convection in PCM and influence assessment of nanoparticle implementation into material on given temperature distribution. Software MATLAB was used for model development, solution and plotting graphs.
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Apparatus for measuring the thermal resistance of the gloves
Pelikán, Jakub ; Fišer, Jan (referee) ; Hejčík, Jiří (advisor)
This thesis deals with common problem health protection at work. Namely hand protection during the work in very cold environment. It’s an analysis of materials suitable for apparatus used for measuring the thermal resistance of the gloves. There was analysed a range of materials. Every single sample was tested for heat conductivity and afterwards was assessed the suitability of materials. Heat was generated by electricity. Ocured heat fields was assessed with thermocamera. After performed experiments of carbon fiber we haven’t reached any satisfying results which we could use for manufacturing of this device. On the other hand kapton film has given very interesting results which we would recommend eventually. Kapton film needs to be modify according to the method listed in the conlusion. This thesis gives us a clear overview and inspiration for additional research of this device. It finds it’s place in research facilities and companies manufacturing protective clothing.
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