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Experimental and Numerical Assessment of the Heat Transfer Coeficients for Industrial Steam Turbine for Siemens Industrial Turbomachinery
Hladík, Petr ; Pospíšil, Jiří (referee) ; Hrabovský, Jozef (advisor)
The subject of this diploma thesis is experimental and numerical assessment of the heat transfer coefficients during condensation of water steam in simplified parts of an industrial steam turbine. This simplified part is a pipe with circular cross section, which is often used in simulations of processes inside the steam turbine. The first part of thesis describes theoretical basics of heat transfer during conduction, convection and condensation. The content of other chapters is description of methods used to determine heat transfer coefficient. These are: ex-perimental analysis performed on a measuring device and evaluated using finite element ana-lysis (FEA), computational fluid dynamics analysis (CFD) in ANSYS CFX and analytical calculations of heat transfer coefficients using mathematical models for condensation. Thesis is concluded by validation and comparison of obtained results.
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Heat transfer coefficient on surfaces of steam turbines
Belko, Milan ; Pavel, Pánek (referee) ; Pospíšil, Jiří (advisor)
This thesis in introductory part aims to analyze the available literature on the heat transfer coefficient in labyrinth seals and rotating discs of steam turbines. The available experiment studies were processed to summarize heat transfer coefficients on the rotating parts of the turbine. Then, this thesis specifies a design calculation to determine the heat transfer coefficient in selected parts of the turbine, exercisable for specific geometric and operating parameters. The outcome of this work is simulation of rotor dilation of operating steam turbine in the program Ansys during cold start of turbine.
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Calculations of steam condensers
Mifek, Roman ; Kilkovský, Bohuslav (referee) ; Jegla, Zdeněk (advisor)
This thesis deals with the calculation procedures for determining the heat transfer coefficient for steam condensers. The first section provides a basic overview for industrial steam condensers and possible procedure for selecting the appropriate type of tube condenser. The next section describes the types of condensation and equations for determining the heat transfer coefficient for various geometries of tubular condensers. In the final section there is performed practical calculation of condenser in Maple software using the above relations. The results obtained in this calculation are compared with the results obtained by professional computational software Chemcad and HTRI.
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Thermal-hydraulic calculation and stress analysis of a heat exchanger
Fiala, Petr ; Létal, Tomáš (referee) ; Nekvasil, Richard (advisor)
Main object of the work is stress analysis of specific parts of tube and shell heat exchanger by using MKP. Each part is judged by two different computation methods. The method based on computation values and the method nearing real condition of operation of device. To approach real load are in the work made basic heat transfer computations for entire device and for analyzed part are computed boundary conductance by using CFD.
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VBA and Maple application in process engineering problematics.
Farkač, Daniel ; Jegla, Zdeněk (referee) ; Kohoutek, Josef (advisor)
The task of the diploma thesis named VBA and Maple Application on Process Engineering Problems is to show the possibilities of using these programming languages for various engineering tasks. Particularly the programming language Visual Basic for Application (VBA), which is a part of MS Office package, is very little used in practise. That´s why this thesis solves the complex task of a furnaces design process; the topic was reccomended by the supervisor prof. Ing. Josef Kohoutek, CSc. Specifically, the thesis deals with calculations of heat transfer and optimization of the height of extended surfaces of tubes in the convection section of process furnaces. The entire task is elaborated in VBA and runs in Excel. After entering the input information, the created program first calculates the size and heat output of the convection section, but it can also optimize the height of extended surfaces in different parts of the convection section and thus minimize investment costs.
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Design and stress analysis of temperature and force sensor in hot rolling process.
Nejedlý, Pavel ; Pohanka, Michal (referee) ; Horský, Jaroslav (advisor)
In the process of hot rolling is roll surface thermo-mechanically stressed. To define lifetime of roll or to increase it by change of thermal mode, temperatures and forces acting on this roll need to be known. For this purpose should be used sensors, that are placed near by surface of roll. Aim of the first part of diploma thesis is to debug 2D computing model (MKP) to achieve the match of temperature graphs with experimentally measured values, which was recorded by temperature sensors in real process of rolling. In the second part the same temperature boundary conditions are applied on 3D model, which is used to solve mechanical strength check of the temperature sensor. The last part of thesis is design and verification of mechanical strength of the designed force sensor. The used boundary conditions were acquired in Laboratory of heat transfer and flow. The computing system ANSYS 11 is used to design a model of geometry and numerical calculation. This diploma thesis will be used as donating solution for the granted project, which started in this year with Laboratory of heat transfer and flow partnership.
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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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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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Heat transfer on sprinkled tube bundle
Copek, Tomáš ; Pospíšil, Jiří (referee) ; Kracík, Petr (advisor)
This bachelor thesis named Heat transfer on sprinkled tube bundle deals with experimental assesment of heat transfer coefficient on sprikled tube bundle. Its goal is to measure, compare and evaluate values and trends of heat transfer coefficient on external surface according to flow rate of cooling water. Evaluation will be focused on size of pitch between tubes, type of tubes surface and influence of temperature gradient. Measurement was ongoing at atmospheric pressure. Warm water flowing in tube bundle is cooled by cold sprinkling water. Tube bundle consists of ten tubes located horizontaly beneath each other with smooth, grooved or sanblasted surface. Distance between tubes vary from 15 to 35 milimetres. Measurement of two temperature gradients 15-40 and 15-45 (15°C is temperature of sprinkling water in distribution tube; 40°C or 45°C is temperature of water entering the tube bundle) is carried out for each pitch and tube surface.
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