National Repository of Grey Literature 127 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Use of renewable energy in the food industry
Čederle, Jakub ; Tuhovčák, Ján (referee) ; Hejčík, Jiří (advisor)
This thesis deals with the use of renewable energy sources (RES) in the food industry, specifically in the brewing sector. The first part of the thesis is devoted to the research of individual RES, while the second part focuses on the description of the brewing industry and the beer production process. In the practical part of the thesis, the energy requirements of the selected microbrewery were analysed, which served as a baseline for the assessment of the possibility to cover its needs with RES. The use of a heat pump, the installation of photovoltaic panels and heat recovery in wort cooling by means of a plate heat exchanger were considered. The work is concluded with an evaluation of the individual solutions.
Feasibility of EU decarbonisation plans from the production capacities point of view
Vařejka, Tomáš ; Pešek, Martin (referee) ; Hejčík, Jiří (advisor)
The presented master's thesis aims to process a critical study on the feasibility of decarbonization plans in the EU from the perspective of production capacities. Decarbonization, or the reduction of greenhouse gas emissions from the burning of fossil fuels, is the main tool for transitioning to a carbon-free society. The thesis presents the main European decarbonization plans, such as the Green Deal or Fit for 55, and evaluates the EU's previous climate policy. In accordance with these plans, decarbonization scenarios for the transition to new carbon-free energy sources are proposed for the target years 2030 and 2050, both at the EU and national level for the Czech Republic. Based on the proposed scenarios, the required capacity of new carbon-free energy sources is determined. The thesis also includes the determination of current production and implementation capacities and an assessment of their limitations. The result of comparing the required new sources with the current capacity is a proposal on how to increase these production and implementation capacities to theoretically achieve the set decarbonization goals.
Ground source heat pump with R744 refrigerant
Nevoral, Michal ; Bouchal, Patrik (referee) ; Hejčík, Jiří (advisor)
The aim of the thesis is to design a ground-water heat pump with refrigerant R744 for low temperature heating systems. The work is divided into two main parts. In the first part is ex-plaining the principle and distribution of the heat pump with the description of the individual components and the differences in refrigerants. In the practical part, the refrigerant cycle of the heat pump is designed and calculated. After optimizing of the calculation, individual components, the electrical parts and the construction of the heat pump are designed.
Heat pump control system
Kundrata, Radim ; Pech, Ondřej (referee) ; Hejčík, Jiří (advisor)
The rising costs of heating buildings are leading to the widespread use of energy-saving heat sources, including heat pumps. The purchase of a heat pump is a significant investment. A way to reduce the purchase costs is to build it yourself or to convert it from an old air-conditioning unit. One of the obstacles in converting these devices is their subsequent integration into the heating system of the house and their control. Therefore, the paper describes the design of a simple control system, which is primarily intended for these cases. It is based on the ESP32 microcontroller series. The control system has 13 configurable inputs for thermometers or digital inputs, 6 of which also allow analog input. It also has 9 outputs for relay connections. The control system can be connected wirelessly, its configuration is done via a web interface. The control system includes equithermal control, user adjustable thermostat, various methods for evaporator defrosting, bivalent source control, compressor protection elements, refrigerant overheating measurement. All setting options are described in the text of the thesis. The source code for the microcontroller and the web configuration page are included in the appendix of the thesis.
Design of a heat pump for a cooling system of controlled wine fermentation
Brucháček, Rudolf ; Hejčík, Jiří (referee) ; Toman, Filip (advisor)
This bachelor’s thesis deals in the first part with research on the issues of heat pumps and the use of cooling devices for controlled fermentation of wine. The second part involves the design of a specific heat pump for this cooling device. It is an air-to-water heat pump with the possibility of reversible operation. The design of the device components is realized using calculation software from well-known companies specializing in this field (Select 8, SSP G8, Coolsector 2, Coolpack). The output of the thesis is a specific component design and an energy evaluation using the coefficient of performance.
Low temperature heat exchanger
Křivánek, František ; Toman, Filip (referee) ; Hejčík, Jiří (advisor)
The aim of this work is to design a low-temperature heat exchanger for a lyophilization device. The theoretical part of the work includes a basic description of lyophilization technology, a literature review of heat transfer at low temperatures with a focus on suitable construction materials and heat transfer fluids, and an overview of utilized heat exchanger designs. The practical part of the work deals with the actual design of the heat exchanger for indirect cooling in two variants, one of which utilizes a direct vaporization system of the heat transfer fluid, while the other focuses on purely liquid cooling.
Performance simulation of a solar PV system for a single-family home
Veličková, Kateřina ; Hejčík, Jiří (referee) ; Charvát, Pavel (advisor)
Recently, renewable energy resources have become an urgent issue, as a result there are many papers focused on photovoltaic power plants and their performance simulations. These simulations not only allow us to assess the reduction of dependency on the fossil fuels, but also to calculate costs saving. This work considers the operation of a single-family house in the Czech Republic. However, a summary of photovoltaic potential factors is presented as well as the most common applications used for performance simulations of photovoltaic power plants. In practical part of this work, the load profile for common household is determined based on the data provided by the Energy Market Operator, alternatively the load profiles of two households owning a plug-in hybrid are also determined. The performance simulation is assembled in TRNSYS application and the results are summed up in the last chapter.
The Mpemba effect and its use in applications
Wittek, David ; Hejčík, Jiří (referee) ; Mauder, Tomáš (advisor)
Hot water appears to freeze faster than cold water. Already Aristoteles mentions this seemingly meaningless fact in his writings. However, to this day no one has been able to fully clarify this phenomenon. Work is focused on factors, which may affect the freezing process of liquids. The composition of the experimental set up will be designed to approach the conditions of the pioneer of scientific research on this issue, E. Mpemba. He has obtained the most convincing results confirming existence of the phenomenon. Based on results, it will be discussed possibilities of practical application, for example for saving time during freezing.
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.
Absorption chiller
Najbrtová, Zuzana ; Bouchal, Patrik (referee) ; Hejčík, Jiří (advisor)
The master thesis on the Absorption chiller is devoted to the dimensioning of the operating points of the absorption chiller cycle. The thesis is based on the required realistic parameter such as cooling capacity, temperature of the chilled fluid and temperature of the driving hot water. The proposed duty cycle is single stage with two heat recovery exchangers, one between weak and rich solution, and the other between liquid and gas refrigerant. The working fluids of this cycle is ammonia and water. The thesis is divided into theoretical and practical parts. The theoretical part summarizes the basic knowledge of absorption cooling, including an explanation of the principle of trigenera-tion in which the proposed unit is to operate. The practical part deals with the actual design and calculation of the operating points, parameters of the secondary working fluids and the performance of the devices themselves. The calculation is compared with the real absorption units and the compressor unit.

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