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New Elements of Heat Transfer Efficiency Improvement in Systems and Units
Turek, Vojtěch ; Klemeš,, Jiří (referee) ; Odstrčil, Miloslav (referee) ; Jegla, Zdeněk (advisor)
Zvýšení efektivity výměny tepla vede k poklesu spotřeby energie, což se následně projeví sníženými provozními náklady, poklesem produkce emisí a potažmo také snížením dopadu na životní prostředí. Běžné způsoby zefektivňování přenosu tepla jako např. přidání žeber či vestaveb do trubek ovšem nemusí být vždy vhodné nebo proveditelné -- zvláště při rekuperaci tepla z proudů s vysokou zanášivostí. Jelikož intenzita přestupu tepla závisí i na charakteru proudění, distribuci toku a zanášení, které lze všechny výrazně ovlivnit tvarem jednotlivých součástí distribučního systému, bylo sestaveno několik zjednodušených modelů pro rychlou a dostatečně přesnou predikci distribuce a také aplikace pro tvarovou optimalizaci distribučních systémů využívající právě tyto modely. Přesnost jednoho z modelů byla dále zvýšena pomocí dat získaných analýzou 282 distribučních systémů v softwaru ANSYS FLUENT. Vytvořené aplikace pak lze využít během návrhu zařízení na výměnu tepla ke zvýšení jejich výkonu a spolehlivosti.
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Modeling of the thermal effects on living tissue during electroporation process
Kafka, Roman ; Cipín, Radoslav (referee) ; Červinka, Dalibor (advisor)
The work deals with the current state of knowledge of heat transfer in living tissue. It is described here what the distribution of heat is affected with and the existing calculation options. For solving Pennes equation using finite element method COMSOL Multiphysics 5.4 is used. From the current state of the published studies, three are selected and described, each using a different approach. Based on the benefit of each of the studies described, a simple model of its own that simulates an ablation catheter attached to cardiac tissue is solved. A change in electrical conductivity as a function of the electric field intensity is taken into account, but there is also a comparison with anisotropic tissue that has electrical conductivity in different directions. The result of the calculation is voltage distribution, density of electric current and losses, temperature distribution in the model at several time points and graph of temperature development over time.
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Mathematical description of dynamic heat exchanger
Hvožďa, Jiří ; Hnízdil, Milan (referee) ; Kůdelová, Tereza (advisor)
This bachelor's thesis deals with an analysis of a dynamic heat exchanger, with neglect to position, described by the system of ordinary differential equations. It includes necessarily theoretical basis of ordinary differential eqations and thermomechanics, a study of ordinary differential eqations' solution existence, overview of types of heat exchangers according to various aspects.
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Thermo-physical parameters of exo-sleeves and their application in simulation programmes
Zajíček, Roman ; Kuzma, Zbyněk (referee) ; Roučka, Jaromír (advisor)
Thesis discusses exothermic sleeves. The first chapter briefly described the defects can occur during solidification. Further, there are provided methods for removing these defects. The method is described in detail using risers with an emphasis on the exothermic sleeves and thermo-physical parameters characterizing these sleeves. It also describes the influence of these parameters on the accuracy of computer simulations. In the final part of the work is done measuring of the real casting, which is then simulated in the Quikcast.
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Combination of numerical mathematics and neural network for the model of breakout prediction
Srba, Jan ; Štětina, Josef (referee) ; Mauder, Tomáš (advisor)
This thesis deals with creation of breakout prediction model implemented via artificial neural network in MATLAB, hence it contains theoretical description of artificial neural networks and also presents how the networks were used for the breakout prediction problem. In addition, models of heat conduction through the mold wall were created and used for generating neccesary data for proper training of artificial neural network. The thesis contains proper description of used numerical methods for solving the heat conduction problems. In the thesis are presented partial results and also results of testing created artificial neural network with usage of real data.
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Verification of the model for predicting the properties of the combustion process
Horsák, Jan ; Kilkovský, Bohuslav (referee) ; Jegla, Zdeněk (advisor)
This work thoroughly analyzes a previously created computational model for predicting characteristic properties of the combustion process in an experimental combustion chamber. Any found shortcomings of the original model are removed and the model is further improved prior to its application on 11 real cases of combustion tests performed at various conditions and with various fuels. Data provided by the model are confronted with the data obtained during the combustion tests and the model accuracy is evaluated, based on local heat flux along the length of the combustion chamber. Finally, the overall usefulness of the model is determined by the means of evaluating the acquired accuracy values, and further possibilities of model improvement and use are presented.
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Design of cooling plate for vibration test stand
Drtílek, Juraj ; Mauder, Tomáš (referee) ; Štětina, Josef (advisor)
This research deals witch thermal analysis of cooling plate for vibrational test of turbochargers. In introduction, the reader is familiar with principle of turbocharging, his importance and history. In this part of research is described also testing of turbochargers, especially vibration tests and its issue. The main part of research is focused on heat transfer, especially conduction, convection and radiation. This part is also completed with calculation of heat transfer coefficient, which is nessesary for thermal analysis of plate for vibration test stand, which is made in the last part of this work.
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