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Parametric study of air cooled heat exchanger
Tichý, Marek ; Toman, Filip (referee) ; Baláš, Marek (advisor)
This diploma thesis deals with air-cooled heat exchangers. Firstly, these types of heat exchangers are described theoretically in many different variations. The following part of the diploma thesis is focused on thermohydraulic calculations that aim to determine the resulting heat transfer coefficient and the necessary heat exchange surface. This calculation depends on the chosen piping and its geometry. The design of a specific heat exchanger follows the calculation, which is documented with a projection drawing. In the following section, a parametric study is conducted to investigate the dependence of heat exchanger properties on changes in its geometry.
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Comparison of analytical and numerical solution of selected problems of compound bodies from Strength of materials II
Tichý, Marek ; Majer, Zdeněk (referee) ; Ševeček, Oldřich (advisor)
The Bachelor´s thesis deals with stress-strain analysis of selected compound bodies from the subject of Elasticity and Strength II. The Wolfram Mathematica software was used for analytical calculations, and for the numerical calculations was used software called Ansys Workbench, which uses the finite element method. An overview of some compound bodies from engineering practice was compiled, and two compound bodies with different geometric variations were selected for the purpose of comparing the analytical and numerical approaches under assumptions of small and large deformations. The results of both solutions are compared in graphs and evaluated.
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Studies of plasma disruptions in the COMPASS tokamak
Matveeva, Ekaterina ; Tichý, Milan (advisor) ; Van Oost, Guido (referee) ; Gerasimov, Sergei (referee)
Title: Studies of plasma disruptions in the COMPASS tokamak Author: Ekaterina Matveeva Department: Department of Surface and Plasma Physics Supervisor: RNDr. Milan Tich'y, Dr.Sc., Univerzita Karlova, Katedra fyziky povrch˚u a plazmatu Abstract: Plasma disruption in a tokamak is an important physical phenomenon, when there is a sudden loss of plasma confinement and rapid drop of plasma current. During the disruptions, there is significant mechanical stress on the construc- tional structures of the tokamak and thermal stress on the first wall. Allowable number of disruptions with the maximum plasma parameters in the ITER toka- mak (international thermonuclear experimental reactor under construction) will be very limited. Therefore, investigation of disruptions and their consequences is a key problem for sustainable operation of tokamak devices. The thesis focuses on studies of current quench phase and related currents flow- ing in the vacuum vessel at the COMPASS tokamak. An extensive disruption database was collected and critical disruptions' parameters were determined. Plasma current was measured at 5 toroidal position as a consequence of data acquisition system improvement that allowed reliable measurements by magnetic coils without analogue integrators. Special divertor tiles were installed in or- der to...
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Probe methods for diagnostics of plasmatic systems for deposition of thin films
Zanáška, Michal ; Tichý, Milan (advisor) ; Dvořák, Pavel (referee) ; Straňák, Vítězslav (referee)
The doctoral thesis deals with an experimental study of several diagnostic techniques intended for plasma diagnostics and diagnostics of thin films during reactive sputter deposition. A relatively novel probe diagnostic technique called Floating harmonic probe for measurement of the ion density and electron tem- perature in technological low-temperature plasma is studied. A Langmuir probe is commonly used, however, its application in conditions where non-conducting films are being deposited can be problematic or unreliable. The floating harmonic probe measurement technique deals with this inherent problem of the Langmuir probe. The Floating harmonic probe results are compared to those obtained by a classical Langmuir probe in non-reactive DC continuously driven discharge, and its applicability in reactive regime during deposition of iron oxide thin films is proved. The work deals also with a modification of the Floating harmonic probe called Phase Delay Harmonic Analysis Method which is intended for diagnostics of pulsed driven discharges. The second part of the thesis is devoted to a new proposed method for in-situ diagnostics of thin films. This method monitors the capacitance and resistance of a thin film during deposition up to the frequencies in the kHz range. This new method could be used for...
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Determination of n-octanol/water partition coefficient (Kow) of perfluorinated acids
Skrottová, Anežka ; Rucki, Marian (advisor) ; Tichý, Miloň (referee)
Perfluorinated compounds are organic compounds in which all hydrogen atoms in a carbon chain are substituted with fluorine atoms. These compounds are highly stable, persistent and bioaccumulative. They are purely anthropogenic compounds contained in biota and abiota. Partition coefficient between n-octanol and water is the essential toxicological parameter of a compound. This parameter helps us to assess behaviour of compound in the environment as well as in the living organisms. The shake flask method and the RP-HPLC method were employed to measure the Kow of nine perfluorinated acids. Using the shake flask method, the surface activity of compounds and the acid dissociation caused false results of the measurement. But behaviour of these compounds in the environment can be assess. Accurate and precise results were measured by the RP-HPLC method using an acetate buffer. Log Kow of perfluoro- carboxylic acids, with the carbon chain length of 5-14, were found out, their final value ranging between 1.66 and 5.10. Log Kow of acid with 12 carbons was estimated based on the linear regression of dependence of log Kow on the number of carbons. There were significant differences in the results obtained by various software. Thus, the results cannot be considered relevant. These software are not suitable for...
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Experimentální studium centrální a okrajové oblasti prstence plazmatu na tokamaku Compass
Štefániková, Estera ; Tichý, Milan (advisor) ; Hron, Martin (referee)
High-resolution Thomson scattering system on the COMPASS tokamak provides electron temperature and density profiles in the central and edge plasma region. The spatial resolution in the edge plasma region is optimized for edge transport barrier studies. Formation of characteristic edge profiles (pedestals) is observed during high-confinement mode, i.e. the core electron temperature and density are raised up by the value of pedestal height. Both the electron and density pedestals are well-fitted by a modified hyperbolic tangent (mtanh) function, a five parameter model giving important parameters such as pedestal height and width, necessary for further analysis of the physics behind the transport barrier formation. A fitting technique of the full radial profiles of electron temperature, density and pressure during H-mode is also described. Using the fitting, electron temperature and density on top of pedestal are statistically processed to find a possible threshold for various H-mode regimes.
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