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The effect of boiler tube bundle fouling on its service life
Volná, Kateřina ; Ing. Zdeněk JŮZA, Ph.D., MBA (referee) ; Naď, Martin (advisor)
Fouling of tube bundles in boilers on the flue gas side affects not only the service life, but also the boiler heat output and increases maintenance and operating costs. Therefore, it is necessary to minimize or completely eliminate this process. This thesis focuses on comparison of the service life and the heat output of the tube bundles with and without deposit in the coal fired boiler. Simulations of flue gas flow in area of tube bundles with and without deposit are performed using ANSYS Fluent software, which shows that the surface of tube bundles with deposit is much less heated than the surface without deposit. The thermal loads of tubes obtained by the CFD analysis are applied to the model, which is created in the program ANSYS Mechanical, where the calculation of the temperature field in the cross section of the pipe is realized. The effect of fouling on creep life and heat output is then evaluated based on simulation results. The results show that fouling increases creep life, but significantly reduces heat output of heavily fouled tubes. Hence the flue gas flows at a higher temperature to the rest of the tube bundle, and the service life of those tubes will therefore probably decrease.
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Evaluating and modeling of fouling process in heat exchanger
Čirka, Martin ; Kilkovský, Bohuslav (referee) ; Jegla, Zdeněk (advisor)
This diploma thesis discusses fouling processes and mechanisms of industrial heat exchangers, with focus on shell side fouling of heat transfer area by flue gases, and eventually taking fouling into account, or more precisely its modeling and predicting by calculation. Thermal-hydraulic design of heat exchanger is focused mainly on shell side, as flue gases are dominant process medium in terms of fouling and heat transfer. Based on available operational data of evaluated industrial heat exchanger, specific process has been developed to determine by calculation, or more precisely predict change of fouling factor throughout operational period of heat exchanger. Usage and various options of this specific calculation technique are being discussed in conclusion, whether there is a potential to use this technique regarding more complex operational inputs or prediction of fouling process for different operational regime of heat exchanger.
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New Elements of Heat Transfer Efficiency Improvement in Systems and Units
Turek, Vojtěch ; Klemeš,, Jiří (referee) ; Odstrčil, Miloslav (referee) ; Jegla, Zdeněk (advisor)
Zvýšení efektivity výměny tepla vede k poklesu spotřeby energie, což se následně projeví sníženými provozními náklady, poklesem produkce emisí a potažmo také snížením dopadu na životní prostředí. Běžné způsoby zefektivňování přenosu tepla jako např. přidání žeber či vestaveb do trubek ovšem nemusí být vždy vhodné nebo proveditelné -- zvláště při rekuperaci tepla z proudů s vysokou zanášivostí. Jelikož intenzita přestupu tepla závisí i na charakteru proudění, distribuci toku a zanášení, které lze všechny výrazně ovlivnit tvarem jednotlivých součástí distribučního systému, bylo sestaveno několik zjednodušených modelů pro rychlou a dostatečně přesnou predikci distribuce a také aplikace pro tvarovou optimalizaci distribučních systémů využívající právě tyto modely. Přesnost jednoho z modelů byla dále zvýšena pomocí dat získaných analýzou 282 distribučních systémů v softwaru ANSYS FLUENT. Vytvořené aplikace pak lze využít během návrhu zařízení na výměnu tepla ke zvýšení jejich výkonu a spolehlivosti.
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Cleaning of ventilation systems and potential energy savings
Lapáček, Milan ; Rubina, Aleš (referee) ; Máša, Vítězslav (advisor)
The main aim of this thesis is to explore fouling of air ducts and its influence on energy consumption of HVAC systems. The first part focuses on typical parts that create the IAQ in buildings and on evaluating energy consumption of air transportation. The following section deals with the theories of fluid flow, flow regimes and pressure losses that are created as a side effect. The thesis outlines possible methods of assessing the impact of pollution with an emphasis on pressure losses and their influence on the fan power consumption. The actual experimental measurement, conducted in a selected industrial plant, is focused on an influence of cleanness of textile diffuser on HVAC device power consumption. For the further research of this process, measuring equipment with suitable measurement method is designed and constructed.
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Analysis of heat exchanger
Nosek, Miroslav ; Kilkovský, Bohuslav (referee) ; Jegla, Zdeněk (advisor)
The diploma thesis is focusing on research of possible damage mechanism of U-tubes in a heat exchanger placed within a gas waste incinerator unit in a factory dealing with chemicals manufacturing. In the first phase of the research, in which a thermo – hydraulic calculation is being made, a specialized software tool HTRI Xchanger Suite® v6.00 is used. Using the software it is possible to simulate certain operational conditions in which the heat exchanger operates. The output from the first phase of the solution is to obtain a set of temperatures of the tube material throughout the length of the tubes. These data are consequently used in the second phase of the analysis. The second phase of the analysis is dealing with thermal lenght dilatation differences assessment between tubes in the tube bundle as a predected reason of oversize tension formed in tube material and damage following afterwards. Conclusions of the calculation made in the second phase of the analysis are then checked by calculation via ANSYS Workbench 11.
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Modelling of fouling and its influence on technical-economic characteristics of tubular heat transfer equipment in units for thermal processing of wastes
Keliš, Michal ; Kohoutek, Josef (referee) ; Jegla, Zdeněk (advisor)
The main subject of this study is the improvement of predicative ability of previously developed mathematical model for prediction of so-called “fouling critical velocity”. Attention is devoted especially to the flue gas side fouling process on active heat transfer surfaces in tubular heat exchange tube banks installed in waste incineration process plants and also a technical – economic analysis based on obtained results. The model improvement consists among others in taking into account another forces (electrostatic, capillary etc.) haven't yet been considered, which influence the mutual contact between flue gas particles in case of sedimentation fouling or the contact between particles and heat exchanger tube walls respectively. The improved model has therefore more predicative ability to the reality of fouling process. The results are used for technical – economic analysis, which determines an optimal heat exchanger design with respect to fouling. Furthermore, the algorithm of this analysis, essential fouling mechanisms, fouled heat exchanger surface cleaning methods as well as fundamental knowledge of fouling coefficient prediction are presented, whereas the emphasis is placed on industrial tubular heat exchange equipment installed in waste incineration process plants.
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Operating fouling of process and power equipment
Sénáši, Martin ; Pačíska, Tomáš (referee) ; Jegla, Zdeněk (advisor)
Bachelor thesis describes the issue of fouling of heat exchangers. This thesis briefly describes the fouling mechanisms and introduces the issue of consideration fouling in the design of heat exchangers. From gained information subsequently on simple calculation examples demonstrate using basic calculation methods impact of fouling on process stream. It also describes the impact of fouling on the technical and economic solutions of heat exchangers.
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Risk assessment design margin of process and power equipment
Horsák, Jan ; Pačíska, Tomáš (referee) ; Jegla, Zdeněk (advisor)
This work is devoted to description of methodology of determining process and power equipment design margins, which is based on assessment of a relative process importance of the equipment in question. The methodology is theoretically analysed, brought into context of common design practice and demonstrated on actual cases. Substantial part of this work analyses heat transfer in general as a base of heat exchanger design process.
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Fire control equipment and its emergency use with a view to the safety of escaping people
VÍTOVÁ, Eliška
The bachelor thesis entitled "Fire control equipment and its emergency use with a view to the safety of escaping people" is aimed at providing public information on the basic kinds of fire control equipment and their use. The thesis stresses the fact that the availability of fire control security equipment in the households is rather poor considering its main aim is the protection of the owners´ health and assets. The results were obtained with the use of questionnaires supplied to the public and by the survey of statistical data received from particular fire brigades including the numbers of deaths in household fires. Installing the basic kinds of fire control equipment which I mentioned in my thesis can considerably improve the chances of survival as well as decrease related health risks and damage to property.
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