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Calculation of the distribution of temperature field of induction machine
Suk, Jiří ; Dostál, Lukáš (referee) ; Janda, Marcel (advisor)
The issue of this bachelor’s thesis is calculation of the distribution of temperature field of induction machine. There is used three different methods of calculating which are compared in the conclusion. First method is lab measuring of surface temperature on different spots on the machine while unloaded without active cooling. Temperature is measured on four spots using different devices. Another way how to calculate temperature field is computer simulation in ANSYS Workbench using finite elements method. In this method is necessary to create real-based model of motor in CAD system. In this case Autodesk Inventor 2015 was used. Last method was simplified analytics calculation using heat circuit of the stator part. Last but not least is comparison of all used methods, results and accuracy of calculation.
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Development of Method for Visualization and Measuring of Temperature Fields in Air with using Thermovision Camera
Pešek, Martin ; Šafařík,, Pavel (referee) ; Černecký,, Jozef (referee) ; Pavelek, Milan (advisor)
This work deals with the measurement of temperature fields in the air using an infrared camera. The dissertation describes the opportunity of measuring the temperature field in the air and the characterization of the developed measuring method. In the next part there are introduced the beginning of thermography imaging and the field of usability of the new infrared measuring method. Further, the theoretical foundations of the thermography measuring method in the temperature fields in the air are described. In the theoretic background there are described the analysis of heat conduction in an auxiliary material, the determination of dynamic properties of the method and the analysis of radiation, which has an influence on infrared imagining. This method requires an insertion of the auxiliary material into the non-isothermal air flow, which can allow for the study of the temperature distribution in air. For effective visualization of temperature fields in the air using an infrared camera, the selection of the appropriate auxiliary material, on which the air temperature displays, is crucial. In the next part of the doctoral thesis, there is a description of static measuring properties of auxiliary materials. The usability range of the measuring method is determined from these properties. In the thesis there are presented the description of the device for the measurement of 2D temperature fields in the air and the description of the measuring device for 3D measurements of temperature fields in the air using an infrared camera, which can also be used for measurements of temperature fields in small enclosed spaces through a viewing window. For the practical use of the method, the detailed methodology of measuring temperature fields in the air by an infrared camera was developed and its applicability was demonstrated on practice examples. The developed measuring method can be used in many areas of research and in practice.
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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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Optimization of Slab Concasting Via Numerical Model of Temperature Field
Mauder, Tomáš ; Čarnogurská, Mária (referee) ; Pyszko, René (referee) ; Raudenský, Miroslav (referee) ; Kavička, František (advisor)
The thesis deals with optimization of the continuous slab casting process. The thesis summarizes the basic analytical and empirical findings concerning to the solidification process, the numerical modeling and the selected optimization techniques. Physical conditions and factors that affect the quality of steel including their relationships are also described. The basis of the solution strategy is the original numerical model of the temperature field in its off-line version. The numerical model was verified by the real historical data. The optimization part is based on the fuzzy logic implemented above the numerical model. The optimization algorithm is used for the optimal control of the casting process. The universal usage of the optimization model is demonstrated on several cases, e.g. the finding of optimal casting parameters that ensure the high quality of products, the optimal reactions on breakdown situations, the determination of an optimal relationship between casting parameters, etc. Based on optimization results, the suitable caster modification to increase the surface temperature at the unbending point was proposed. The whole concept of the numerical and optimization model is general and it can be applied to arbitrary slab or billet continuous casting.
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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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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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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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Temperature measurement in electric machines
Halfar, Ivo ; Huzlík, Rostislav (referee) ; Janda, Marcel (advisor)
The bachelor's thesis Temperature measurement in electric machines deals with beginning and exuding of the heat of electric motors and measuring of the temperature. The temperature is one of the most important values in diagnostic. High temperature could damage an isolation and it could tend to destroy of the whole machine. The temperature influences their magnetic properties on motors with permanent magnets. If you reach the Curie temperature it could come to its demagnetisation. Measuring of the temperature is important to verify allowable warming of motor or more precisely its spooling. The measuring of the temperature is needed for making motors with minimum of charges and its worth at the end. We could use two methods for measuring the temperature. It is contact and noncontact method. Warming and decomposition of the temperatures it is possible to appoint also with help of theoretic computations which are getting of the method of final elements. A lot of computer programs is using this method. Because of the existence of many sorts of electric motors, one of the viewpoints is the principle of working, another one is the construction. I concentrate on problems of asynchronous motors. In this bachelors thesis I have done theoretical calculation and contact and noncontact method of measuring of warming of the asynchronous motor.
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Complex strength design of condenser
Denk, Jakub ; Naď, Martin (referee) ; Lošák, Pavel (advisor)
This diploma thesis focuses on strength design of steam condenser. The goal of the thesis is to make strength calculations for the specific operation conditions, introduce possible solutions, provide recommendations and refer to weak points of such calculation procedures. First, thermal-hydraulic design in HTRI software is performed. Strength calculations respect ČSN EN 13445 standard. Strength calculation with imported temperature field is performed in ANSYS Workbench software. In the next step, another strength calculation is realized in Sant´ Ambrogio software. Results are evaluated in conclusion chapter, including recommendations for the possible following work.
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Temperature distribution of rubber damper of gasoline engine
Knor, Pavel ; Ramík, Pavel (referee) ; Píštěk, Václav (advisor)
The main aim of this master’s thesis is to design the drivetrain of four-cylinder gasoline internal combustion engine with torsional vibration rubber dumper. For the basic parameters of the engine are designed two optional crankshafts. Crankshaft with eight counterweights and crankshaft with four counterweights. The thesis also includes modal analysis of the crankshaft using FEM, and design of the main dimensions of the dumper. The following part describes the calculation of force torsional vibration and safety factor solution of crankshaft fatigue using FEM. The final calculation is of the temperature field in the rubber dumper in selected operating modes.
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