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Thermal radiation in real life
Kalus, Petr ; Zálešák, Martin (referee) ; Klimeš, Lubomír (advisor)
This bachelor's thesis deals with the impact of heat transfer by radiation on the life around us. The research part summarizes the fundamental laws and concepts necessary for understanding the given issue. Furthermore, it describes and analyzes phenomena in everyday life where radiation is dominant. The greatest attention has been devoted to solar radiation, followed by the greenhouse effect, along with its influence on global warming. The thesis also includes a procedure for calculating heat transfer by radiation between two surfaces, based on which a Python script was written. Subsequently, a standalone application with a graphical interface was developed. The conclusion of the thesis focuses on describing the software development process and provides examples of test cases in thermomechanics.
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Green fuels for small combustion engines
Záhorský, Lukáš ; Klimeš, Lubomír (referee) ; Štětina, Josef (advisor)
Tato práce konfrontuje dostupnost a funkci různých alternativních paliv pro malé spalovací zážehové motory, používané ve sportovním vybavení. Kvůli rostoucím emisím skleníkových plynů a nárustu teploty zemského povrchu, se zdají alternativní udržitelná paliva nezbytná pro zlepšení životního prostředí. V práci je vybráno a vyhodnoceno několik paliv dle jejich vlastností a ekologického vlivu. Nejprve jsou alternativní paliva experimentálně otestována na motorové zkušebně a jednotlivé motorové vlastnosti jsou porovnány. Později je vyhotovena simulace tepelného cyklu motoru k potvrzení výsledků experimentu. Ze všech otestovaných paliv, ekologický ethanol se jeví jako nevhodnější palivo z hlediska výkonových charakteristik. Nicméně, i mixované částečně ekologické palivo E40, které dosahuje nižší měrné spotřeby paliva ale i nižšího výkonu než čistý ethanol, by nemělo být opomenuto. Obecně se dá říct, že všechna alkoholová alternativní paliva dosahují v obou analýzách nižších emisí skleníkových plynů než fosilní paliva. Na základě výsledků z měření je tedy možné tvrdit, že použití alternativního paliva v malých spalovacích motorech bez zásadních úprav může zlepšit jejich výkonnost a ekologii. Je ovšem nezbytné, provést více výzkumu v oblasti alternativních paliv, aby bylo možné zahájit jejich sériovou výrobu a snížit tak dopad dopravního sektoru na ekologii Země.
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Compressed-air energy storage
Strnad, Jan ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
The bachelor thesis is focused on the problematics of compressed air energy storage. It includes a short introduction to the thermodynamics of ideal gases. The suitable geological conditions for the selection of CAES (compressed air energy storage) systems, the advantages and disadvantages of each type, the method of their production, and the process of compressed air accumulation itself were discussed. The thesis presents individual diagrams of compressed air power plants, and special attention is given to the description of the accumulation process. The last section is focused on the description and comparison of two built CAES systems working on an identical concept and also presents information on the unrealized planned CAES systems.
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Optimization of District Heating Nets Components Simulations
Kudela, Libor ; Klimeš, Lubomír (referee) ; Kořista, Milan (referee) ; Pospíšil, Jiří (advisor)
The thesis aims at the computational solution of district heating networks, their numerical optimization, and predictive control considering heat accumulation. Previous studies avoid using the so-called element method because of its computational expensiveness. However, in combination with current development in scientific computing, it adds a new dimension to the old method. This thesis presents a new simulation model of a district heating pipe with complex physics and efficient inverse problem-solving capability, which is the core of predictive control. The findings acquired in this dissertation allow us to maximize the computational effectiveness of simulation components found in district heating networks
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Mechanical energy storage by means of flywheels
Drtil, Lukáš ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
Mechanical accumulation of energy is important part of the balancing grid and accumu-lation of energy in flywheels is one of the most advanced methods of mechanical accu-mulation. Therefore, the aim of this thesis is to analyse materials from which flywheels are made and their most common implementations. This work also contains examples of real application of the flywheels especially as a balancing part of the power grid. Fur-thermore, there are discussed advantages and disadvantages of this type of accumula-tion in this work. The conclusion of the work is an example focused on comparing of investment return between specified batteries and flywheel system.
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Heat recovery in crypto-currency mining
Ošmera, Tomáš ; Pech, Ondřej (referee) ; Klimeš, Lubomír (advisor)
The bachelor thesis deals with the use of residual waste heat from cryptocurrency mining. Due to the high inefficiency of the so-called ASIC mining equipment, almost all of the electrical energy is converted into heat. This paper deals with the possibilities of using and building equipment to dissipate this heat. The device constructed takes advantage of the dielectric properties of the oil from which the heat is removed to the heating system of the house. Using the constructed device it is possible to supply 800-900 W of thermal energy to the heating system of the house.
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Multi-stage compressors
Dostál, Martin ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
This work deals with compressors and their use in practice. It also describes the basic relationships for thermodynamic analysis of multistage compression, which is more energy efficient at high compression ratios. The work also includes an application for thermodynamic analysis of multistage compressors.
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Analysis of thermodynamic cycles of heat pumps
Vendrame, Katia ; Hejčík, Jiří (referee) ; Klimeš, Lubomír (advisor)
This bachelor thesis focuses on heat pumps for residential applications and their functioning. The theoretical part describes components of heat pump and briefly discusses energy sources that can be used. The types of refrigerants, which are currently used in heat pumps, are discussed: except to the broadly used HFC refrigerants, also the use of carbon dioxide is described. Further, the theoretical part includes the theory of thermodynamical cycles used in heat pumps. In the practical part a computer program for a fundamental thermodynamic analysis of heat pumps was created. The functionality and applicability of the program are demonstrated in the solution fo several problems.
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Inverse problems in computational heat transfer with phase change
Kamarýt, Petr ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
This diploma thesis deals with inverse problems in heat transfer with phase change. The first chapter focuses on heat transfer mechanisms including phase change. Second chapter deals with computational solution of heat transfer problems. In the third chapter the inverse problem for heat flux estimation is formulated. Fourth chapter is description of methods, implemented by the author, for computational solution of both direct and inverse heat transfer problems. Solution of inverse problem are obtained by the sequential method and artificial neural networks. Two heat flux types were selected: continuous, piecewise linear and discontinuous, piecewise constant. Obtained result for both cases are comparable. In case of discontinuous heat flux, results are worse than in continuous case.
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Heat transfer in modern automotive lights
Holec, Radek ; Klimeš, Lubomír (referee) ; Štětina, Josef (advisor)
The beginning of this thesis is dedicated to light in general and all different types of vehicle lightning, also deals with various types of light sources and specifically about LED where it describes the temperature change behaviour. Second part deals with heat transfer by conduction, convection, and radiation, it describes quantities and relationships needed for next capitols. In the penultimate part is described thermal management of headlights, therefore different options of cooling and causes of heat generation, and different types of PCBs that are used in automotive. In the last part is proposed the heatsink, which should be used for cooling LED chips of daytime running lights.
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