|
|
CFD modelling of the initial phase of fouling inside convective section of a combustion facility
Zlámal, Filip ; Juřena, Tomáš (referee) ; Strouhal, Jiří (advisor)
The aim of this thesis was to create, based on the knowledge obtained from research, a CFD simulation of initial phase of fouling of solid particles during the combustion of solid fuels. The introduction of the work summarizes the mechanisms of fouling by solid particles. The introduction of the work summarizes the mechanisms of fouling by solid particles. Approaches to modelling the impact and deposition of particles are also described. A model is built, which is implemented in the ANSYS Fluent software with the addition of user-defined functions. The model is tested on a model of the convective part of an experimental device for burning solid fuels.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
| |
|
|
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.
|
|
|
Application of Polymeric Hollow-Fiber Membranes in Air Filtration
Bulejko, Pavel ; Dohnal, Mirko (referee) ; Friess, Karel (referee) ; Svěrák, Tomáš (advisor)
Membrány z dutých vláken jsou široce využívány v aplikacích týkajících se úpravy kapalin jako např. při čištění odpadních vod, v membránových kontaktorech a bioreaktorech, membránové destilaci apod. I když jsou často využívány při separacích směsí plynů, je jejich použití pro mechanickou filtraci aerosolů velmi vzácné. Tato práce se zabývá filtrací vzduchu pomocí polypropylenových membrán z dutých vláken včetně jejich filtrační účinnosti, tlakových ztrát a také zanášením při dlouhodobé filtraci. Filtrační účinnost byla proměřena za použití různých aerosolů jako TiO2 a síran amonný. Tlakové ztráty byly měřeny při různých konfiguracích, tj. různé filtrační ploše a průměru vlákna membrány. Zanášení membrán bylo testováno použitím normovaného prachu definovaného normou ANSI/ASHRAE 52.2. Predikční modely pro filtrační účinnost a permeabilitu/tlakovou ztrátu membrány byly aplikovány na parametry membrán z dutých vláken a porovnány. Tyto membrány mají velikost pórů kolem 90 nm a poměrně nízkou porositu a tím vysoký potenciál pro separaci nanočástic ze vzduchu. Dále byla provedena analýza filtračního koláče a vyhodnocení energetických nároků a porovnány s teoretickými modely. V závěru práce je nastíněn odhad ceny životního cyklu při filtraci pomocí těchto membrán.
|
|
|
Effect of exchanger fouling and heat transfer coefficient
Konopiský, Karel ; Kracík, Petr (referee) ; Baláš, Marek (advisor)
This diploma thesis covers the influence of fouling in heat exchangers and heat transfer coefficient. In the first part of the thesis are covered the characteristics of fouling and its formation, process, and effects on heat transfer surfaces in exchangers. In the next part of the thesis, chemical analysis of cooling water is performed on an extracted sample and the potential of fouling is determined based on the analysis. In the conclusion part, computational models of fouling in the tube side of the heat exchanger are presented; fouling of an actual heat exchanger is calculated and compared with data captured during the operation of the heat exchanger.
|
guest ::
