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Heat storage in solar thermal systems
Mokriš, Lukáš ; Hejčík, Jiří (referee) ; Charvát, Pavel (advisor)
In this bachelor’s thesis are described methods of heat storage in solar thermal systems. Solar energy is retrieved in form of solar radiation, that is processed and stored in the form of sensible heat of solid materials and liquids, as heat of fusion of some material or as chemical heat, which is created during reversible chemical reactions.
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Ventilation and air conditioning of a car cabine
Viščor, Petr ; Hejčík, Jiří (referee) ; Fišer, Jan (advisor)
In this work are described kinds and functions of air-conditioning systems which are used in cars. Further is described heat transfer between car cabin and ambient environment and issue of reduction of air-conditioning energy consumption. Last part of the work contains numerical simulation made by the THESEUS-FE 2.1 software package. This simulation was done on a model of the Toyota Prius car and was focused on effect of glazing on a temperature of the air inside the car cabin during hot summer days.
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Design of Helium liquefaction cycle
Bártová, Jana ; Kracík, Petr (referee) ; Hejčík, Jiří (advisor)
The present master thesis deals with the technologies for gas liquefaction focused on helium. The first part of the thesis contains a description of the history of liquefaction, production and usage of liquid helium, as well as the principles of liquefaction and cooling cycles. In the following part of the thesis is a detailed model of the liquefaction cycle for which radial-axial turbine wheels were designed. The last part of the thesis contains financial analysis of the suitability of using the expander with eddy current brake and the expander with an electric generator.
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Expansion valve replacing with the capillary tube
Devečka, Viktor ; Tuhovčák, Ján (referee) ; Hejčík, Jiří (advisor)
V súčasnosti sa kladie veľký dôraz na znižovanie produkcie emisií, čistotu a kvalitu životného prostredia. Tieto trendy sa týkajú všetkých odvetví, tak isto aj stavebného priemyslu a vykurovania budov. Doposiaľ bolo najrozšírenejším typom vykurovania spaľovanie fosílnych palív. Do popredia sa však dostávajú tepelné čerpadlá a začínajú zaberať výrazný podiel trhu. Kvôli dopytu po tepelných čerpadlách vzrastá počet výrobcov a konkurencia. Cieľom výrobcov je zvyšovanie účinnosti tepelných čerpadiel a zároveň znižovanie výrobných nákladov na dosiahnutie lepšej pozície na trhu. Predložená práca sa zaoberá procesmi prebiehajúcimi v chladivovom okruhu tepelného čerpadla. Skúma správanie chladiva počas kondenzácie a možnosti zvýšenia účinnosti tepelného čerpadla. Zvýšenie účinnosti je dosiahnuté podchladením chladiva počas kondenzácie na zvýšenie tepelných ziskov. To je dosiahnuté zaradením druhého elektronického expanzného ventilu za kondenzátorom. Táto technológia je však finančne náročná. Práca sa zaoberá výpočtom kapiláry na základe praktických meraní, ktorá bude zadržiavať chladivo v kondenzátore a bude plniť podobnú úlohu ako expanzný ventil. Následne sú porovnané výsledky jednotlivých meraní. Výsledky sú porovnané voči jednoduchému systému, kde nedochádza k podchladeniu chladiva. V závere práce je analýza výsledkov jednotlivých systémov.
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Heat pumps testing methodology
Španihelová, Kateřina ; Kamenský, Petr (referee) ; Hejčík, Jiří (advisor)
This thesis deals with the methodology of heat pumps testing. The first part covers the basic principles of a heat pump from the thermomechanical point of view, the description of the heat pump basic components and low-potential heat sources. The next section describes the parameters of heat pumps according to which we can evaluate their effectiveness. The last part is targeted on the issue of testing heat pumps including a description of the test methods and description of the test heat pump air-water.
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Efficiency analysis of the heat source with heat pumps
Miklas, Václav ; Hejčík, Jiří (referee) ; Máša, Vítězslav (advisor)
This thesis is focused on the gross COP analysis of the heat source with heat pumps. In the first part, summary of the heat pump research including progressive technologies is presented. The main part is the case study dealing with the efficiency analysis of the heating system based on air source heat pumps. That includes theoretical formulation of the conditions which affects gross COP of the heat pumps. The main contribution is the evaluation of measured data. The outcome of evaluation is the average COP in the selected period. The outcome also includes dependence of the COP on different conditions and comparison of the evaluated COP and the theoretical one. Consequently, some methods for optimal operating of the heat source are recommended.
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Family house energy requirements audit
Halata, Maxmilián ; Hejčík, Jiří (referee) ; Fišer, Jan (advisor)
The bachelor’s thesis is focused to possibilities of using National calculating tool of buildings energy requirements according to Czech government regulation no. 148/2007 Sb. The tool was applied to calculate energy requirements of chosen family house. Several types of house modifications which can reduce energy requirements are proposed based on results of the audit. Each modification of the house is analyzed from the energetic, construction and economic point of view.
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Energy Management of Administrative and Industrial Buildings
Coufal, Jaroslav ; Jaroš, Michal (referee) ; Hejčík, Jiří (advisor)
Nowadays, energy management is very important in terms of trying to save the environmental impact of human activities. If we want to have beautiful nature around us, it is important to think conscientiously in our consumption. In my bachelor thesis I describe the requirements of energy management. The goal of my work is to define what belongs to energy management and what solutions already exist on the market.
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Cooling of a powerful light source
Tulis, Vojtěch ; Tuhovčák, Ján (referee) ; Hejčík, Jiří (advisor)
The diploma thesis is focused on calculating the thermal resistance of the line light source and the design of the cooling system with ideal inlet temperature. The partial aim of the work is in cooperation with CAMEA spol. s r. o. to determine the thermal resistances of the individual parts of the device and propose modifications so that the total thermal resistance and the maximum temperature are within the limits given by the cooperating firm. The main objective is to design a cooling system with all safety features and recommended regulation for economical and reliable operation. Analytical calculations, CFD simulations and real-world testing are used to determine the desired results. A reduction by 30% in thermal resistance of the printed circuit board was achieved, the thermal resistance of the aluminum profile with the cooling channel was determined and its hydraulic properties were calculated. The current cooling system designed by CAMEA spol. s r. o. for less powerful diodes was verified for use in a more powerful system, and a new cooling system was designed for efficient and economical operation in a powerful diode system.
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