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Daily launches steam turbines and their impact on the life of the turbine
Štěpánová, Lenka ; Kracík, Petr (referee) ; Fiedler, Jan (advisor)
This thesis concentrates on the problem of steam turbines, which require daily cycling by reason of an unstable nature of the energy source. The first part focuses on the current trends which have caused still increasing demand for steam turbines designed for every day start-ups. There is a description of the steam turbine start-up procedure and the heat transfer theory thanks to which the list of the critical parts of the steam turbine has been selected and with respect to these critical points has been created the draft of technical measures for the turbine. The thesis is finished with an evaluation of the life of the steam turbine casing as one of the critical parts and with a proposal for a calculation of a start-up time of the steam turbine.
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Study of the thermal and light conditions in the automobile headlamp with built-in light source of the new generation
Zachar, Martin ; Černý,, Pavel (referee) ; Černý, Pavel (referee) ; Raudenský, Miroslav (advisor)
This thesis deals with automotive headlamps, focusing on layout of temparature field and its influence on thermal stress of used materials, describes their history, kinds and ongoing research. Thesis shortly describes light and its characteristics, heat and heat transfer and means of temperature measurement. Main part of the tesis is dedicated to measuring front headlamp serving as a fog light, concretely measuring temperature field and illuminance depending of ambient temperature. Thesis contains everything from the first preparations, creation of measuring circuit, programming of measuring to processing acquired data. Thesis also compares cooler used for cooling luxmeter sensor, the comparision is between measured values and created simulation.
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Analysis of the thermal resistance of insulation systems from foamed insulants in flat roofs
Rundt, Lukáš ; Žák,, Antonín (referee) ; Žižková, Nikol (advisor)
On many structures there ocurred a problem of expanded polystyrene-based thermal insulation material degradation caused by high temperatures close to glazed areas. In a theoretical part of this Master’s Thesis there are the most common thermal insulation materials described, followed by a brief desciption of flat roof waterproofing materials and a thermal stress of structures. An experimental part describes a design of a methodology for evaluation of thermal resistance properties of foamed insulants in flat roofs and several experiments carried out according to the methodology.
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Development of Methodology for Evaluating the Necessity of Shell Compensators fo Tubular Condensers
Pernica, Marek ; Reppich, Marcus (referee) ; Vincour, Dušan (referee) ; Jegla, Zdeněk (advisor)
This dissertation deals with strength analysis of shell and tube condenser with fixed tube sheet, which is equipped with shell expansion joint. The main aim of this thesis is to develop a methodology for determining of necessity of uses the expansion joint on the shell and tube condenser, while maintaining the safety and reliability of the equipment during operation, based on thermal-hydraulic and strength analyses. Industrial condenser is used as a safety equipment during the operation, therefore special attention is paid to the start-up process. The condenser start-up process is investigated by a number of transient strength and transient thermal analyses, which was solved by specialized software and with analytical calculations. The strength calculation of shell, tube and tube-sheet of shell and tube condenser is developed in detail according the ČSN EN 13445 standard with special attention to shell and tube process media thermal impact on condenser construction. Based on the performed calculations, the methodology for evaluating the necessity of shell expansion joints of tubular condensers was developed.
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Steam turbine start-up
Jelínek, Tomáš ; Kracík, Petr (referee) ; Šnajdárek, Ladislav (advisor)
This bachelor thesis focuses on steam turbine start-up process. The first part of this thesis describes in general terms the basic practices and principles of start-up. The second part deals with the general description of thermal stress on the rotor and stator part. There is also simplified calculation of start-up duration and admissible temperature difference. The last part is a calculation of heat transfer coefficient using inverse heat transfer analysis. There is a comparison of models and measurement data of thermal stress.
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Microbial production of extracellular polymers and their involvement in stress response
Müllerová, Lucie ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
Bachelor’s thesis is focused on the production of extracellular polysaccharide pullulan by microorganism Aureobasidium pullulans, purification of pullulan and its possible use as a cryoprotectant. As a part of this work a description of A. pullulans, pullulan and an overview of involvement in its stress response were provided. In the experimental part growth characteristics of A. pullulans (the strain CCM 8182 was used) and pullulan production during growth in optimal conditions was analyzed. Biomass production was the highest with fructose as a carbon source (3,580 g/l CCM 8182), the highest pullulan production occurred when using sucrose as a carbon source (10,300 g/l F 148). Among three organic solvents used for pullulan precipitation – ethanol, acetone, isopropylalcohol, ethanol was selected as the best for further experiments in ratio 1:2 (fermentation broth:ethanol). Pullulan purity was characterized by HPLC. As a further part of this work, cryoprotectant properties of pullulan at temperatures – 72° C, -18° C, 4° C and 60°C were studied. The presence of pullulan at temperatures – 72° C and 60° C was found to be detrimental to cell viability. At temperatures – 18° C and 4° C the cryoptotectant activity of the polysaccharide was confirmed.
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Reliability of lead free solder joint
Paško, Martin ; Knotek, Tomáš (referee) ; Stejskal, Petr (advisor)
This thesis deals with voids formation in lead-free soldered joint. In theoretical part are described types of voids, voids formation, effect on join reliability, effect reflow profile on voids formation and effect of surface finish on voids formation. In practical part is investigated a effect of thermal stress on voids growth.
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Partial Discharge in Electronic Equipments
Mammadov, Anar ; Maschke, Jan (referee) ; Dřímal,, Jiří (referee) ; Boušek, Jaroslav (advisor)
Tato disertační práce se věnuje studiu částečných výbojů (PD) způsobených poklesem spolehlivosti a životnosti elektronických zařízení a systémů. Diagnostika PD je dnes známá metoda pro vysoké napětí u vysoko-výkonných zařízení. V případě elektronických zařízení PD testování není ale běžně používáná metoda, přestože je zde také potenciál pro vysoké elektrické zatížení vzhledem k velmi krátké vzdálenosti. Tato práce je zaměřena na vyšetřování PD činnosti u elektronických zařízení. Bylo navrženo a provedeno pracoviště pro diagnostiku PD v elektronických zařízeních. Pracovní frekvence se pohybuje od několika stovek Hz až 100 kHz. Maximální amplituda PD testovaného napětí je vyšší než 10 kV. Navzdory jednoduché konstrukci toto zařízení přináší vysokou spolehlivost měření. Více než 300 PD testů bylo provedeno na různých elektronických zařízeních a elektronických součástí,např. na planárních transformátorech a elektronických komponentách používaných při vysoko-napěťových měničích
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