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Influenc of Instability to Critical Heat Flux
Khůlová, Jitka ; Vojáčková, Jitka (referee) ; Suk, Ladislav (advisor)
This bachelor's thesis is elaborating about two-phase flow in the heated channel. It describes flow instabilities and their influence to critical heat flux. The calculation methods of two-phase flow are introduced. The homogeneous equilibrium method is selected for the practical part. The results are evaluated and possible solution to prevent flow instabilities is suggested.
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Design concept of the facility for the educational objectives of the boiling crisis
Vojáčková, Jitka ; Škorpík, Jiří (referee) ; Martinec, Jiří (advisor)
This thesis deals with a design concept of the facility for the educational objectives of the boiling crisis. In the first part, the issue of boiling crisis is explained. There are also examples of some experimental facilities in the world. The second part includes design concept of a loop, which is accompanied by designs of individual devices, such as separator, condenser, exchanger, pump, water tank, electric heater. The thesis also states designs of throttle control, temperature control and flow control.
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Experiments critical heat flux
Štaffa, Petr ; Martinec, Jiří (referee) ; Suk, Ladislav (advisor)
The Bachelor’s thesis deals with phenomenon of critical heat flux in a core of nuclear reactor. The first part is dedicated to describe physical nature of critical heat flux and basic thermo mechanical and hydrodynamics terms. The second part is dedicated to summarize experimental investigations on critical heat flux and their process.
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Departure from nucleate boiling in nuclear reactors
Bednář, Michal ; Števanka, Kamil (referee) ; Foral, Štěpán (advisor)
This bachelor thesis deals with problem of boiling crisis in nuclear reactors and how this problem influences working od nuclear reactor. This thesis is focused on power water reactors, with focus on VVER 1000 reactor type, which fuel assembly is described in this thesis in more detail. In this thesis there are described terms related to boiling crisis and two-phase flow regimes. In the last part, the thesis is dedicated to the correlations for the critical condition and individual correlations are compared.
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Boiling crisis of advanced nuclear fuels
Bírošíková, Martina ; Milčák, Pavel (referee) ; Šnajdárek, Ladislav (advisor)
This diploma thesis deals with a theoretical description of the boiling crisis during intensive heat transfer between the outer surface of the fuel and the coolant and research of the materials and coverage of fuel assemblies with emphasis on the importance of accident tolerant fuel with higher accident resistance. The experimental part ot the work determines the critical heat flux on the examined test sample and interprets the results obtained several times by repeated measurements.
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Experimental and calculational analyses of new generation nuclear fuels
Tioka, Jakub ; Mičian, Peter (referee) ; Števanka, Kamil (advisor)
The search for Accident tolerant fuels (ATF) which is the first part of this thesis is currently one of the most actual topics in the field of nuclear fuels. These fuels must be first successfully tested in operational and also accident conditions for their possible inclusion in commercial use. Following part of the thesis specifically focuses on the boiling crisis in nuclear reactors which can damage the nuclear fuel cladding. Therefore, it is necessary to know the critical heat flux value and the departure from nuclear boiling ratio. Calculations which determine critical heal flux value are placed in the practical part of the thesis. Calculations are compared with the data obtained during experiments. The ALTHAMC12 and the other correlations which are based on the previous measurements are used for the computational analysis.
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Critical Heat Flux on Smooth and Modified Surfaces
Suk, Ladislav ; Kolat, Pavel (referee) ; Katovský, Karel (referee) ; Fiedler, Jan (advisor)
This thesis deals with the problem of critical heat flux (CHF) on technically smooth and treated surfaces at low pressures. The theoretical part presents the basic concepts of two-phase flow and an analysis of existing work on the influence of the surface on CHF. The main part of the work describes the built experimental apparatus for CHF research at low pressures of 100 -1500 kPa (1-15 bar) with a vertical internally heated annular test section. The internal annuli consists of an outer glass tube with an inner diameter of 14.8 mm and an inner tube made of Inconel ™ 625 / Optimized ZIRLO ™ with an outer diameter of 9.14 mm and a heated length of 380/365 mm. CHF experiments on technically smooth surface were performed at outlet pressures 120 kPa, 200 kPa and 300 kPa, at an inlet temperature of 64, 78 and 91 °C and at mass flux of 400, 500, 600 and 800 kg / m2s. The Inconel tubes were tested in two different surface modifications - abraded and bead blasted. Experiments were performed at mass flows of 400, 500 and 600 kg / m2s. The total number of 122 experimental runs were conducted and the results were compared with other literature experimental data. The maximum increase of CHF on abraded / bead blasted tube was 18.12% / 16.17%. The surface structure was analysed by laser microscopy. The wetting behaviour of the surface structures was measured by the sessile drop method. The elemental analysis of the surface was evaluated using the EDS method.
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Scale model of fuel rod for experiments critical heat flux
Kropáč, Ondřej ; Šnajdárek, Ladislav (referee) ; Suk, Ladislav (advisor)
Bachelor thesis deals with scale models for research of critical heat flux. Theoretical research part focusses on material of models their geometry heating methods and measurement of heat of already passed experiments. Practical part includes mathematical model of scale model used in device assembled at Faculty of Mechanical engineering BUT. Last section deals with surface temperture measurement and visualisation using thermography.
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