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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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SMV-2021-61: Professional servis of Dewar vessels for LHe
Srnka, Aleš
Long-term active operation of Dewar vessels for liquid helium is connected with the risk of their damage that could caused significant financial losses and as well danger for their operators. The goal of the research is to guarantee the safe operation and its economical benefit. Vessels are periodically tested for vacuum tightness and relevant boil of rate is measured. Simultaneously are tested security valves and cooling processes of vessels are optimized. We use long time know-how in the field of cryogenics and also our specialized cryogenics equipments and apparatuses. The research is conducted according Contract between MU - CEITEC and ÚPT AV ČR Brno, v. v. i., signed on the 3.2.2020.
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Visualization of selected flows of water and cryogenic helium using tracer particles
Pilcová, Veronika ; Skrbek, Ladislav (advisor) ; Kohout, Jaroslav (referee)
Flow visualization techniques have recently been applied for the investigation of various cryogenic flows of liquid helium. Particle image velocimetry and particle tracking velocimetry techniques, proven in the past as very fruitful in many scientific and industrial areas of research, are being used for the analysis of cryogenic flows. The Joint Low Temperature Laboratory at the Charles University in Prague is the first in Europe to employ flow visualization techniques to investigate liquid helium flows. The approach had to be optimized due to a number of technical and fundamental dificulties, i.e., the optical access to the helium bath and choice of suitable tracer particles. Water experiments at room temperature were performed to prove that the experimental apparatus is well-suited for the low-temperature experiments performed as the main part of the work. The latter focused on thermal counter flow. The results from both, room-temperature experiments and low-temperature experiments are discussed and positively compared with well-known theoretical results.
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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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SMV-2019-29: Professional servis of Dewar vessels for LHe
Srnka, Aleš
The aim of the project is optimalization of the operation of Dewar vessels for liquid helium with\naccent to the safe operation and its economical benefit. Vessels are periodically tested for vacuum tightness and relevant boil of rate is measured. Simultaneously are tested security valves and cooling processes of vessels are optimized. We use long time know-how in the field of cryogenics and also our specialized cryogenics equipments and apparatuses. The research is conducted according Contract between MU - CEITEC and ÚPT AV ČR Brno, v.v.i., signed on the 17.1.2019. \n
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Interaction of laser beam and tracer particles in liquid helium
Hodic, Jan ; Skrbek, Ladislav (advisor) ; Schmoranzer, David (referee)
The thesis resums the base knowledges of the domain of the fluid mechanics, deduction of the Navier-Stokes equations, introduction of the Reynolds number and its difference and a fundamental deduction of the Stokes formula, expressing a depending of the resistance of a fluid on a moving sphere. There are the problematic of turbulence including of energetical spectrum by Kolmogorov, cascade mechanism of disintegration of vortices and Kolmogorov length analysed too. There are introduced vorticity and Rayleigh number the exploration of the classical turbulence using liquid helium 4 in this thesis. There are stated the basical physical possesions of the helium 4 here, including of its phase diagram and double- componental model. Special chapture pays attention to the hydrodynamics o helium 4, especially to the relation from pressure to temeprature. After it comes introduction to quantum turbulence, including of the basical formulae and description of the used experimental method of the partical tracker, as well asthe basical motivation of the problem. There is calculated an approximate calculation of the interaction between a particle and a laser beam, as well as an exact calculation for a spherical particle. During the calculation is presumed uncompressible, non-vorticose flowing, using basical formulae for...
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Visualization of selected flows of water and cryogenic helium using tracer particles
Pilcová, Veronika ; Skrbek, Ladislav (advisor) ; Kohout, Jaroslav (referee)
Flow visualization techniques have recently been applied for the investigation of various cryogenic flows of liquid helium. Particle image velocimetry and particle tracking velocimetry techniques, proven in the past as very fruitful in many scientific and industrial areas of research, are being used for the analysis of cryogenic flows. The Joint Low Temperature Laboratory at the Charles University in Prague is the first in Europe to employ flow visualization techniques to investigate liquid helium flows. The approach had to be optimized due to a number of technical and fundamental dificulties, i.e., the optical access to the helium bath and choice of suitable tracer particles. Water experiments at room temperature were performed to prove that the experimental apparatus is well-suited for the low-temperature experiments performed as the main part of the work. The latter focused on thermal counter flow. The results from both, room-temperature experiments and low-temperature experiments are discussed and positively compared with well-known theoretical results.
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SMV-2014-14: Baffle plates for the 75 mm neck of the helium Dewar CH-500
Srnka, Aleš
Research and development in the field of thermal shielding of cryogenic vessels. It included selection of material with suitable emisivity and absorptivity of thermal radiation, analysis of cryogenic vessel from the point of parasitic thermal fluxes and calculation of baffles quantity and position in the vessel neck. Experimental tests proved rightness of calculation and showed that only by use of properly designed baffles it is possible to reach minimal helium evaporation rate.
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