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Steam turbine - condensation formation and discharge
Zouhar, Adam ; Filip, Patrik (referee) ; Fiedler, Jan (advisor)
Master thesis is dealing with the issue of condensate creation and removal from the Nesher Ramle steam turbine during start-up and steady state. At the beginning a preliminary calculation of heat balance and the turbine itself is done. It is followed by description and design of drainage system supplemented by calculation of the steam flow through the orifices. Steam flow calculation was done via S. D. Morris, Pavelek with Kalčík and Ambrož, all three methods were compared. The main goal is the theoretical calculation of the amount of condensate created during start-up which is influenced by its initial state from which it is started. Three default states are considered, cold, warm and hot. In the last chapter the comparison of theoretical calculation with the measured data on real turbine is done and it is supported by the evaluation of the data from the measurement of the steam turbine at steady state on maximum power and half power. From the steady state analysis, percentage of water flow to expander from the total amount of condensate formed in the turbine were obtained.
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CFD simulation flow of steam in the unregulated extraction of steam turbine
Filip, Patrik ; Pospíšil, Jiří (referee) ; Fiedler, Jan (advisor)
Diploma thesis named CFD simulation of the steam flow in the unregulated extraction of the steam turbine is about an analysis of the balance piston impact on the area of the steam turbine, where the extraction is located. First part describes basic knowledge of the steam turbine in general. At the end of this chapter, there is a description of the solved steam turbine. Next chapter is about introduction to the CFD. Practical part deals with a construction of 3D models, meshing and setting of the boundary conditions in the program ANSYS CFX. The main part of this thesis summarizes the results of the CFD simulation and stipulates the temperature range on the extraction pipe. In conclusion, there is a recommendation how to determine design temperature of the extraction pipe influenced by the balance piston.
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Balancing Rotors of Steam Turbines
Filip, Patrik ; Šnajdárek, Ladislav (referee) ; Kracík, Petr (advisor)
This bachelor’s thesis is a technical research dealing with issues of balancing turbine rotors and generally describing international standarts commonly used for balancing rotors. The first part is about unbalance in general context. The next part classifies types of rotors, standarts for balancing rotors and balancing methods. Then there is a description of a balancing device. The last part of this thesis includes a step by step process of balancing a specific rotor.
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The influence of morphometric changes of gray and white matter on brain functional connectivity in schizophrenia
Görnerová, Natálie ; Horáček, Jiří (advisor) ; Zach, Petr (referee) ; Filip, Pavel (referee)
More than a century has passed since a clear definition for schizophrenia was established, yet, the etiology, neuropathological and pathophysiological mechanisms of this psychiatric disorder still, to a large extent, remain to be elucidated. In the theoretical part of this dissertation, we review current classification and pathophysiology of schizophrenia, paying a particular attention to the findings from structural and functional imaging techniques. These techniques demonstrate that patients with schizophrenia tend to have reduced volume of grey matter, reduced integrity of white matter and a disrupted inter-regional functional connectivity (FC). The temporal association between structural changes, already detectable on imaging before symptoms appear, and development of disrupted FC remains to be uncovered. At the same time, current knowledge does not fully explain the link between disrupted FC and disturbed experience of self-awareness, a core symptom of schizophrenia. In addition, it is necessary to develop novel effective methods to prevent relapse and prevent the progression of neurobiological changes in the brain. In the practical part of this dissertation, we designed a study with three different groups of subjects aiming to fulfil three key aims that would help us to fill the gaps in...
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Correlation between the onset of beadless character of nanofibrous webs and rheological characteristics of electrospun polymer solutions
Zelenková, Jana ; Peer, Petra ; Filip, Petr
An overwhelming majority of applications of nanofibrous webs requires sufficiently smooth character of nanofibres surface. This character is apart other parameters strongly influenced by a concentration of chosen polymeric material in the solvents. Qualitative attributes roughly depend on the prepared concentration, specifically whether it belongs to one of the four basic regions: dilute, semidilute unentangled, semidilute entangled and concentrated. A concentration separating the latter two regions is often taken as a zero-th approximation indicating an onset of beadless nanofibrous webs. The present contribution uses as a more precise indicator behaviour of so-called phase angle relating viscous and elastic moduli, in other words mutual participation of viscous and elastic components. To this aim three frequently used polymers were used: copolymer of poly(vinylidene fluoride) and hexafluoropropylene (PVDF-co-HFP), poly(ethylene oxide) (PEO) and poly(vinyl butyral) (PVB). For materials exhibiting first a constant behaviour or moderate decrease in a phase angle for lower concentrations, an approximation of the starting concentration is given by a concentration value where a phase angle curve starts to decrease, apparently reflecting a more progressive viscoelastic nature. As shown, such approximation provides relatively very good approximation enabling to eliminate a traditional trial-and-error method.
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Viskoelastické vlastnosti ferrokapaliny - Studium normálových napětí
Šustková, Hana ; Krakovský, Ivan (advisor) ; Filip, Petr (referee)
Viscoelastic properties of ferrofluid - Study of normal stresses differences Master Thesis Hana Šustková Abstract: Since 1960, a liquid becoming strongly magnetized in the presence of a mag- netic field, called ferrofluid, is known. This colloidal liquid made of ferro- or ferrimagnetic nanoparticles, with diameter in range 10-20 nm, suspended in a carrier fluid. This work focuses on the study of the viscoelastic properties of a selected ferrofluid - the steady-state and dynamic properties of the fluid with comparison to a standard fluid (basis fluid, etc.) and a MR fluid. Rheological measurements are carried out using a commercial rheometer. A magnetic cell for this rheometer is designed and built. In this magnetic cell the experiments are realized, the whole system is calibrated and the experiments performed. The ferrofluid APG513a, MR-fluid and reference fluid were used. Study of normal stresses differences (N1,N2) in liquids is carried out. Ac- cording to derived theoretical model, the course of N1 and N2 should be strongly dependent on the field - this was studied directly by measuring of the normal forces or indirectly applying the Laun's rule. A good accordance of theory and experiment was found and an anisotropic behaviour of ferrofluid was studied. The shear-thinning ability of the ferrofluid in normal direction...
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Antibacterial electrospun membrane prepared from poly(vinylidene fluoride)-co-hexafluoropropylene with lauric acid monoacylglycerol
Zelenková, Jana ; Peer, Petra ; Pleva, P. ; Janalíková, M. ; Sedlaříková, J. ; Filip, Petr
The aim of this study was to prepare an antibacterial nanofibrous membrane using electrospinning technique. The nanofibrous membranes were spun from polymer solution of poly(vinylidne fluoride)-co-hexafluoropropylene (PVDF-co-HFP) dissolved in N,N´-dimethylformamide. Monoacylglycerol of lauric acid (MAG C12) was used as an antimicrobial agent at the concentrations ranging from 1 to 3 wt%. The impact of MAG C12 incorporation on the rheological, structural and antibacterial properties was investigated. The rheological tests of polymer solutions, as steady shear and oscillatory shear, proved that addition of MAG C12 changed marginally rheological quantities such as viscosity, elastic (storage) and viscous (loss) moduli. Measurement of mean nanofibres diameter indicated a slight decrease with increasing MAG C12 concentration. Antimicrobial activity of PVDF-co-HFP nanofibre membranes with incorporated MAG C12 against Gram-positive bacteria Staphylococcus aureus and Gram-negative Escherichia coli was studied. An antibacterial activity was revealed for the samples containing MAG C12 at all concentrations against Gram-positive bacteria Staphylococcus aureus by the disk diffusion method.
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Steam turbine - condensation formation and discharge
Zouhar, Adam ; Filip, Patrik (referee) ; Fiedler, Jan (advisor)
Master thesis is dealing with the issue of condensate creation and removal from the Nesher Ramle steam turbine during start-up and steady state. At the beginning a preliminary calculation of heat balance and the turbine itself is done. It is followed by description and design of drainage system supplemented by calculation of the steam flow through the orifices. Steam flow calculation was done via S. D. Morris, Pavelek with Kalčík and Ambrož, all three methods were compared. The main goal is the theoretical calculation of the amount of condensate created during start-up which is influenced by its initial state from which it is started. Three default states are considered, cold, warm and hot. In the last chapter the comparison of theoretical calculation with the measured data on real turbine is done and it is supported by the evaluation of the data from the measurement of the steam turbine at steady state on maximum power and half power. From the steady state analysis, percentage of water flow to expander from the total amount of condensate formed in the turbine were obtained.
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Dependence of morphology of electrospun PVB nanofibres containing fumed silica on elasticity of the processed solutions
Peer, Petra ; Polášková, M. ; Filip, Petr
Application of various types of fumed silica gives a possibility to tailor a degree of hydrophilicity or hydrophobicity of the resulting electrospun nanofibrous mats where as a basic polymeric material is taken poly(vinyl butyral) (PVB) solved in methanol. Presence of fumed silica substantially changes viscoelastic attributes in comparison with the neat PVB solution.\nThe aim of this contribution is to compare morphological structures of the resulting electrospun mats generated from the solutions with presence and absence of various types of fumed silica differing in surface morphology, size and the specific surface area. This comparison is based on the rheological characteristics with the emphasis to elasticity of the pre-processed solutions. The differences in elasticity among fumed silica based solutions are indeed remarkable. The obtained results show that elasticity does not play a crucial role in creation and morphological aspects of the corresponding nanofibrous mats including fibres diameter.
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