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Concentrator photovoltaic systems
Straškraba, Vojtěch ; Solčanský, Marek (referee) ; Vaněk, Jiří (advisor)
The subject of this bachelor´s thesis is to introduce concentrator photovoltaic systems, history of their foundation, evolution and application, principles of function and description of technology including its construction, optics, special photovoltaic cells and their cooling. The practical part of thesis describes the experimental concentrator photovoltaic system build in cooperation with Solartec s.r.o. company. The system is used to test hypotheses and study the behavior during its operation. The aim is to measure concentration ratio, temperature and electrical characteristics and to compare advantages of active and passive cooling of photovoltaic cells.
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Night Cooling in Condition of Czech Republic
Šíma, Jiří ; Katunský,, Dušan (referee) ; Plášek, Josef (referee) ; Šikula, Ondřej (advisor)
The PhD thesis deals with the theoretical evaluation of the potential use of night cooling techniques in condition of the Czech Republic. Mainly aims to evaluate the potential of night cooling, which uses the physical phenomenon of radiation against the night sky. This technique is widely used mainly in the dry and hot regions where there are the most suitable climatic conditions for this cooling method. The work is based on the current state of knowledge in the area of passive and low-energy cooling systems. These knowledges are applied to the conditions of Czech Republic and by using simulations of the energy, behaviour of the buildings explores the benefits in terms of improving of the internal microclimate and from the perspective of economy operation of conventional cooling equipment. In order to establish the benefits of night cooling on the operation of the building in the dynamically changing conditions, the modular simulation program TRNSYS was used, which is suitable for the analysis of energy systems of buildings and their behaviour. The results of simulation results were converted to thermal comfort parameters of the PMV and the PPD.
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Car cabin passive cooling system performance study
Viščor, Petr ; Hejčík, Jiří (referee) ; Fišer, Jan (advisor)
The work is focused on issue of passive cooling in a cabin of a car. The basic principles and mechanisms of heat transfer are described in the theoretical part and the quality of cabin environment in terms of thermal comfort and air quality is discussed as well. Next part of the work describing the principles of ventilation and air conditioning of cabins and possible methods of passive cooling are discussed. Passive cooling means decrease of temperature of cars interior, without need of energy supply from car battery, or fuel. The last part of the work includes numerical simulation of selected methods of passive cooling using the THESEUS-FE 3.0 software. Simulations were performed on model of Volkswagen Polo car and primarily were focused on testing of functionality of various methods of passive cooling.
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The influence of internal thermal storage mass used in passive houses' construction systems on their summer thermal stability
Němeček, Martin ; Hraška,, Jozef (referee) ; Katunský,, Dušan (referee) ; Kalousek, Miloš (advisor)
In recent years we may observe a growth in construction of passive houses and low energy houses using lightweight constructions such as modern wooden houses. It is assumed that wooden houses keep overheating more comparing to brick houses during summer period. Due to the lack of research in this field the paper investigates the influence of internal thermal storage mass in passive houses constructions on their summer thermal stability under the Czech climatic conditions. Only sensible heat accumulation without a usage of phase change materials is examined. Differences between wooden houses comparing to brick-built houses are emphasized. Objects of research are mostly residential passive houses in low energy building standards. However, the results of research might be applied to different types of buildings as well. The first section outlines theoretical fundamentals. For the research itself various scientific research methods were used, such as basic mathematical calculations, experimental temperature measurement of two buildings (detached house in Dubňany and in Moravany) and numerical simulations. Own tribute to the research was first of all discussion on the topic of thermal accumulation and structures heat capacity calculation. Experimental measurements outlined conclusive evidence about the importance of internal thermal storage mass in respect of interior summer overheating. The research confirmed that the highest interior temperature reached is mostly influenced by solar gains through unshaded windows. However, the influence of internal thermal storage mass is not remote. If we compare standard timber-framed wooden house to the hole ceramic bricks-built house, the wooden house will overheat by 0,5°C more during a standard day. Wider spread in the maximum temperature reached was measured for lightweight consturctions wooden houses without any internal thermal storage mass. Therefore, such structures should have an additional layer of thermal storage mass.
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Ultrasonic measurement system
Ondraczka, Lukáš ; Solčanský, Marek (referee) ; Vaněk, Jiří (advisor)
The work deals with development and assembly of ultrasonic airflow measurement module for measurement of air flowing around photovoltaic panel. This system allows quantification of photovoltaic panel air cooling. The work contains development of sine wave generator, bridge amplifier and receiver with passive band pass filter, amplifier and comparator. It also deals with digital part realization. This digital part is formed by Renesas 78K0R microcontroller on demo board. The last part of this work contains testing of the whole system in aerodynamic tunnel and on photovoltaic panel installation.
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The concept for passive cooling of the VVER-1000 reactor
Lamoš, Pavel ; Suk, Ladislav (referee) ; Martinec, Jiří (advisor)
This thesis is focused on the design of passive cooling system for a nuclear reactor VVER- 1000.This type of reactor is located in the Czech Republic in the location of Nuclear power plant Temelín. The thesis states an overview of the different cooling systems of nuclear power plants. The thesis is focused on passive safety system especially on passive cooling system, so there was done an overview of currently used passive safety system. In the work is discussed nuclear safety and the maximum projected accident of VVER-1000, which is called LOCA accident. In the design part of the thesis was done thermal calculation of heat exchangers. Exchangers are designed as condensers with a natural flow, where cooling of system is provided by outside airflow in case an accident. The results are evaluated at the end of the thesis.
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Optimization of a lightweight pitched roof in order to reduce summer heat gains
Svobodová, Sylvia ; Rubina, Aleš (referee) ; Sedlák,, Vladimír (referee) ; Matějka, Libor (advisor)
The thesis deals with the topic of overheating of attic rooms during the summer period. In vast majority of family houses and apartment houses with inhabited attic spaces is the roof solved as lightweight. This kind of roof assembly is not able to sufficiently resist the summer boundary conditions and leads to increased heat gains in the interior. In this work, the attention is drawn entirely to the heat penetration through the roof. Different aspects of passive cooling were applied to the roof and the impact of each change was assessed. This concerns the color of the tiles, thermal accumulation, reflective surfaces and the ventilated air layer. The temperature and velocity profiles in the ventilated cavity were monitored and an analysis of the ventilated cavity efficiency was conducted. For individual analyses was used software – based on the principles of the Finite Element Method or the dynamic simulation software. Also other methods were employed: long-term measurement of temperatures on roof models; short-term measurement of surface temperature of various kinds of roof tiles; and laboratory measurement of reflexivity. Also the effect of insect grilles on the air flow is discussed; which was tested on a ventilator track. In this publication are explained the principles of natural convection; boundary layers and the theory of the coefficient of heat transfer. This work includes a standard of the precise calculation methodology for ventilated roofs which was developed for the purpose of creating a user-friendly guide. The results of individual analyses show, a definitely positive effect of the ventilated cavity on the heat gain reduction of attic rooms. The current technical solution of a roof ridge provides the exhaust of the water vapor from a roof assembly; but for providing ventilation for reducing heat gains is insufficient. This lead to a concept of an innovative roof ridge design which enhances the air exchange between the cavity and outdoor environment.
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Passive heat dissipation using carbon-based material
Genco, Ondřej ; Brázdil, Marian (referee) ; Pospíšil, Jiří (advisor)
The content of the diploma thesis is evaluation of the usability of carbon composites in the space industry. The aim of this work is to assess whether carbon composites can find application in mechanical systems of passive thermal protection of artificial objects. Model examples demonstrate the principle of operation of selected passive thermal protection. The evaluation is realized based on the results of thermal analysis. Analytical formulas from field theory of heat transfer are used as a calculation method. The diploma thesis consists from two parts. The theoretical part briefly describes the mechanisms of heat transfer, selected types of passive thermal protection and properties and applications of carbon composites. The practical part consists of the assignment, calculation and evaluation of three examples. The results show that carbon composites can compete with commonly used materials for specific requirements.
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Energy-efficient building of Bosonohy Primary School
Vlha, Daniel ; Blasinski, Petr (referee) ; Počinková, Marcela (advisor)
The aim of this master thesis is to design a nearly-zero energy primary school in Brno-Bosonohy. The thesis consists of 3 parts. The first part contains architectural and structural design. The second part deals with the design of the concept of building services. The building is designed without a basement and has three above-ground floors. The structural system includes longitudinal masonry wall and prestressed prefabricated floor panels. In the lower part of the building there is a lunchroom, above which there is an operating roof. In the higher part of the building, there are 4 form classes for a total of 120 children, a language lab, a laboratory and a atelier. The building is heated by a ground-water heat pump with deep bore holes, which are also used for hot water heating. The ventilation has a heat recovery system with high efficiency. Photovoltaic panels are installed on the roof. The third part analyses data from a local survey at the primary school. The analysis is focused on the temperature in the room in the summer season, and then the management of building services is optimized to energy consumption. The conclusions from the third part were applied to the design of the school, which is the subject of the first and second parts of this master thesis.
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