National Repository of Grey Literature 324 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Physical properties of layered materials with Van der Waals bond
Michal, Ondřej ; Pospíšil, Jiří (advisor) ; Míšek, Martin (referee)
This thesis focuses on the study of van der Waals materials predicted to be high- temperature ferromagnets and methods of the influence of the value of magnetic ordering temperatures. We focused on the well-known van der Waals ferromagnet VI3 and its doping with Se and Te. The Curie temperature of undoped VI3 is about 49 K. The doping with Se and Te changed the TC only slightly, within 1 K. The VSe2 and VTe2 were also prepared in a polycrystalline form to test their magnetic properties. We attempted to prepare CrSeBr by physical vapour transport method; however, with no satisfactory result. Multiple phase products with binary stoichiometries were obtained. 1
Use of surface water as a low-temperature source for heat pumps
Jordanov, Alexandr ; Špiláček, Michal (referee) ; Pospíšil, Jiří (advisor)
First part of my diploma thesis contains research of ground water, refrigerants and heat pump including its inner components. Second part contains calculation of heat exchanger water – antifreeze, which use heat from a river and it will be used for input to heat pump water – water.
Heat Transfer during Condensation of Steam-Air Mixture Flowing in Vertical Tube
Toman, Filip ; Masaryk, Michal (referee) ; Kořista, Milan (referee) ; Pospíšil, Jiří (advisor)
This thesis deals with the problem of condensation in the presence of non-condensable gases with a focus on heat and mass transfer inside a vertical pipe. The introductory part of the thesis is dedicated to the research analysis of the given issue. The attention is focused on the physically correct description of the events at the interface of the gas phase and the condensate film, as well as on the inclusion of the influence of the presence of non-condensable gases. Scientific hypotheses were developed based on this analysis. Subsequently, the objectives of the dissertation are formulated and the methods by which the objectives of the dissertation are solved, are presented. As part of the data evaluation, an analytical model was created enabling the quantification of heat and mass transfer for the measured conditions. This model was used to test variations of computational relationships published by various authors in the literature. The mathematical solution is supplemented by realized experimental measurements of the condensation coefficient of heat transfer and the total coefficient of heat transfer inside the pipe during the condensation of the steam-gas mixture in vertical pipes of three diameters, namely 16, 20 and 26 mm. At the end of the thesis, the most suitable combination of already published analytical relations is selected and is carried out as part of its refinement, using regression analysis.
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
High temperature energy storage
Roden, Lukáš ; Špiláček, Michal (referee) ; Pospíšil, Jiří (advisor)
Because of an increase share of renewable energy, there is a need to develop energy storage technologies, whether it is the electricity or the heat one. The main goal of this thesis is to design and assess a high temperature energy storage used for a long-term accumulation of a thermal energy. The designed storage is calculated for the needs of a family house with photovoltaic panels. It is used numerical method in the Excel software to simulate behaviour in storage. One of the biggest lack is a storage is large number of tubes, which are needed for a heat delivery into and out of the storage. This and the other related lacks make it impossible to a cost-effective application without the appropriate modifications.
Hydrogen filling station
Kaše, Jakub ; Šnajdárek, Ladislav (referee) ; Pospíšil, Jiří (advisor)
Presented master’s thesis deals with hydrogen filling stations, their concepts, design, and operation. The importance of hydrogen as an energy carrier, its properties, and the implications of these properties for the selection of materials suitable for hydrogen applications are described. In order to understand the decisions made in the design of the station, the hydrogen life cycle from production through transportation and storage to use is presented. This is followed by an evaluation of the cycle in terms of economics and environmental impact. The review part of the paper concludes with an introduction to fuel cell vehicles, which includes an overview of the selected passenger and commercial vehicles, and a description of hydrogen filling stations. The filling stations are discussed in terms of concepts and components, and an overview and analysis of selected implementations is also included. The computational part of the thesis focuses on the design and technoeconomic analysis of a hydrogen filling station with a daily capacity of approximately 50 kg/day and an hourly capacity of 6 vehicles/hour for the needs of the logistics company Zásilkovna s.r.o. A station variant with hydrogen gas delivery in pressure vessels was chosen. Three possible designs of the station were compared. The hydrogen filling station can be designed for the specified parameters without any problems. However, the analysis of the results showed a very strong dependence of the acquisition and operating costs on the nominal compressor power. Therefore, the design of the hydrogen filling station requires further optimization, which limits the direct applicability of the presented results.
Industrial heat pump
Pinkas, Marek ; Špiláček, Michal (referee) ; Pospíšil, Jiří (advisor)
The diploma thesis deals with the issue of industrial heat pumps. Its aim is to describe the technologies of heat pumps and their use in industry, where they are already often used to recover waste heat. The work is devoted to compressor and absorption heat pumps. The main parts of the heat pump are presented and described here. Emphasis is also placed on the working materials used. Real applications of industrial heat pumps are also presented. At the end, two variants of the application of the heat pump in cooperation with the cogeneration unit are proposed. In the first case, a compressor heat pump was proposed, and in the second, an absorption heat pump. The heat source for the heat pump is water from the wastewater treatment plant.
On-line calculators for the design of renewable energy installations
Ondráček, David ; Pospíšil, Jiří (referee) ; Linda, Jakub (advisor)
This thesis focuses on the field of renewable energy sources (RES). It focuses on the topic of computational tools that manage the design process of a system using RES. These tools are introduced, their calculation methodology is described and then they are evaluated. As a part of this thesis there is also introduced a design of a unique calculation tool. This tool calculates the energy balance of a dwelling using solar energy and a heat pump.
Energy supply of the ski resort
Turčina, Lukáš ; Skála, Zdeněk (referee) ; Pospíšil, Jiří (advisor)
The environmental targets of the European Union Member States are to achieve carbon neutrality in the next few years by producing green energy. To offset the impact of climate change causalities, it is crucial to increase the share of renewable energy resources as well as to reduce the dependence on fossil fuel imports. The main focus of the thesis is to increase energy sourced from alternative resources in ski resorts. Furthermore, a specific design of a wind power plant located directly in the ski resort together with the storage of the remaining energy is introduced to achieve the thesis’ objective. To select a suitable wind turbine, there is a need to choose a proper construction site that should dispose of stability and good-quality wind conditions. The performed analysis concentrates on the wind speed and frequency on the identified site. As a result, the performance of the selected wind turbine can be calculated. Moreover, given the turbine power and wind frequency, the amount of energy produced can be calculated. The potential electricity production is then compared with the ski resort’s consumption. The findings suggest that with suitable wind conditions and proper planning of energy production and storage, it is possible to cover a significant amount of the resort’s consumption. However, the model is dependent on the speed and stability of the wind, which may be highly volatile over time. Nevertheless, even such small steps can be crucial to achieving the set goals and can indicate the direction in which society will move towards.
Accumulation of energy in "heat batteries"
Janečka, Filip ; Kudela, Libor (referee) ; Pospíšil, Jiří (advisor)
Thermal energy storage is an important alternative to other, more common methods of energy storage, such as electrochemical batteries, as most of the energy used in homes is in the form of heat. The use of thermal energy storage therefore skips the step where electricity is converted into heat, which can increase the efficiency of the whole process and reduce energy costs. In this paper, five important thermal energy storage methods are described and evaluated with respect to their use by an individual in a single family home as well as for use in high energy demand applications (central heating, power generation, etc.). The five heat storage methods are: ground storage, sand storage, PCM (phase change material) storage, thermochemical storage and hydrogen storage. Emphasis is placed on highlighting the advantages and disadvantages of each type of thermal storage reservoir, showing pilot implementations and comparing them with each other. Furthermore, an evaluation of the seasonal storage capability of the different thermal storage systems is made, which shows that the only storage guaranteed to be capable of almost unlimited storage time is the thermochemical storage system. Also in this work, a water heat storage tank for a single-family house is proposed, which was chosen because of its good scalability, proven functionality and relatively simple design.

National Repository of Grey Literature : 324 records found   1 - 10nextend  jump to record:
See also: similar author names
1 Pospisil, J.
46 Pospisil, Jan
17 Pospíšil, Jakub
46 Pospíšil, Jan
2 Pospíšil, Jaromír
6 Pospíšil, Jaroslav
2 Pospíšil, Jindřich
6 Pospíšil, Josef
2 Pospíšil, Juraj
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