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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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Development of Methodology for Evaluating the Necessity of Shell Compensators fo Tubular Condensers
Pernica, Marek ; Reppich, Marcus (referee) ; Vincour, Dušan (referee) ; Jegla, Zdeněk (advisor)
This dissertation deals with strength analysis of shell and tube condenser with fixed tube sheet, which is equipped with shell expansion joint. The main aim of this thesis is to develop a methodology for determining of necessity of uses the expansion joint on the shell and tube condenser, while maintaining the safety and reliability of the equipment during operation, based on thermal-hydraulic and strength analyses. Industrial condenser is used as a safety equipment during the operation, therefore special attention is paid to the start-up process. The condenser start-up process is investigated by a number of transient strength and transient thermal analyses, which was solved by specialized software and with analytical calculations. The strength calculation of shell, tube and tube-sheet of shell and tube condenser is developed in detail according the ČSN EN 13445 standard with special attention to shell and tube process media thermal impact on condenser construction. Based on the performed calculations, the methodology for evaluating the necessity of shell expansion joints of tubular condensers was developed.
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Mathematical simulation of temperature profile in the subsoil and creation of a model corresponding its real state
Charvátová, Pavlína ; Katunský,, Dušan (referee) ; Ostrý, Milan (referee) ; Čupr, Karel (advisor)
Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
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Numerická analýza teplotního pole v konstrukci obvodového pláště dřevostavby rodinného domu s ohledem na možné způsoby osazování otvorových výplní
Kopal, Ondřej
This thesis describes the temperature field in the envelope wooden structures with regard to possible ways of mounting hole fillings. Furthermore, in this work we can find a description of the propagation of heat in the building structure. The challenge is to create a 2-D models of the selected design solutions for the mounting hole fillings in the envelope wooden buildings. Numerical simulation is performed in a computer software based on the finite element method under the given boundary conditions. The emphasis is on comparing the results of numerical simulations for two design solutions fitting windows using the same track of the structure. In conclusion, the results for both design solutions compared and evaluated.
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Numerická simulace pohybu teplotního pole v CLT panelu
Grégr, Jan
Thesis examines the thermal properties of cross laminated timber (CLT). Experi-mental measurement was carried out in heat flow meter. There were measured samples of spruce CLT with dimensions 600 x 600 mm of various thicknesses and number of board layers. The properties were also measured within two different humidity states. The results, especially of the thermal conductivity, are compared and the influence of factors on thermal properties of CLT is researched. There are also numerical models, created in ANSYS software, on which were simulated conditions in heat flow meter and real conditions. The thermal flux through panel cross section was analyzed.
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Temperature field in solid fuel
Ptáček, Pavel ; Šnajdárek, Ladislav (referee) ; Pospíšil, Jiří (advisor)
The diploma thesis deals with a temperature field in a solid fuel during the combustion process. At the beginning of this thesis, research of available literature was conducted to obtain information about the composition of wood, properties affecting the combustion process, and the basics of heat transfer. Afterward, the temperature profiles of the samples were recorded during the measurement in the observation furnace. The temperature profiles of samples of six different sizes which were made of spruce and beech wood were subsequently evaluated and compared. Based on experimentally obtained data, a mathematical model was created in the OpenModellica software. Finally, the results of the mathematical model were compared with experimentally obtained data and appropriate conclusions were deduced.
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Interaction of microwave radiation with moisture in porous building materials
Paťha, Martin ; Šuhajdová, Eva (referee) ; Šuhajda, Karel (advisor)
This thesis deals with interaction of microwave radiation with wet in porous material. It examines the distribution of the temperature field, the efficiency of the method and the financial demands of the method. The most important part of this thesis was an experiment, from which all important values ??were based. The first part deals with the necessary theory and the second part is the experiment itself. The experiment was carried out for three levels of material wet. Eight samples were used for this experiment, which remained unchanged throughout the experiment. The thesis draws on previous researches that were carried out on this or similar topic.
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The effect of boiler tube bundle fouling on its service life
Volná, Kateřina ; Ing. Zdeněk JŮZA, Ph.D., MBA (referee) ; Naď, Martin (advisor)
Fouling of tube bundles in boilers on the flue gas side affects not only the service life, but also the boiler heat output and increases maintenance and operating costs. Therefore, it is necessary to minimize or completely eliminate this process. This thesis focuses on comparison of the service life and the heat output of the tube bundles with and without deposit in the coal fired boiler. Simulations of flue gas flow in area of tube bundles with and without deposit are performed using ANSYS Fluent software, which shows that the surface of tube bundles with deposit is much less heated than the surface without deposit. The thermal loads of tubes obtained by the CFD analysis are applied to the model, which is created in the program ANSYS Mechanical, where the calculation of the temperature field in the cross section of the pipe is realized. The effect of fouling on creep life and heat output is then evaluated based on simulation results. The results show that fouling increases creep life, but significantly reduces heat output of heavily fouled tubes. Hence the flue gas flows at a higher temperature to the rest of the tube bundle, and the service life of those tubes will therefore probably decrease.
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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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Numerické simulace teplotního a vlhkostního pole ve dřevě v prostředí se zvýšenou teplotou
Kubelková, Květa
The thesis deals with numerical simulation of temperature field with internal heat sources and experimental verification of this model in an environment where the high temperatures are applied (during thermal modification of wood). The work was further extended by analysis of coupled heat and monture transfer in the wood. Designed mathematical models are solved numerically using software COMSOL Multiphysics based on the finite element analysis (FEM). The chemical reactions occur due to decomposition of woodconstituents (cellulose, hemicelluloses and lignin) are taken into account in present study. These reactions are usually not solid in known models. The results of numerical simulations of temperature field, including pyrolysis model, are compared with experimental measurements for verification of the proposed model. Contribution of this thesis is the possible application of the proposed model for the design and optimization of thermal modification Schedule with respekt to wood species and sample dimensions.
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