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Velocity profile measurement downstream of swirler
Zejda, Vojtěch ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
A burner is very important device in process furnaces that significantly affect the production of emissions during the combustion process. One of the key things in development of the modern low-NOX burners is the evaluation of flow field downstream of an axial blade swirler inside the burner. The computational fluid dynamics (CFD) is often used to predict the attributes of the flow. Predicted values should be validated with measurement. It is the reason why the velocity fields for several choosen swirlers were measured. The hot wire anemometry was choosen and the dual-sensor probe was used during the measurement. The data can be then used for CFD validation. This thesis describes procedure of measurement set-up. The experimental facility was designed according to the anemometry method. The new probe traversing system was designed, which provides desired accuracy. Five different swirlers were measured. Large data set, need for customized post-processing and control over calculation procedures lead to new software design. For each swirler the velocity profiles were gathered and the swirl numbers calculated. That final data were transferred in to graphical format. Uncertainty of measured data was calculated. Results show counter-rotating flow in some areas closed to the swirler. Some drawbacks of current measurement set-up are discussed. Based on the thesis reader can obtain the information and knowledge for consequent measurements of swirl burners velocity profiles.
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Simplified computational modelling of biomass grate combustion
Floková, Kateřina ; Vondál, Jiří (referee) ; Hájek, Jiří (advisor)
The aim of this thesis is to assemble simplified computational 3D model for straw grate combustion, based on data provided by detailed computational 1D model. This thesis is organized as follows. Firstly, current state of CFD grate combustion modelling is described. The main body of this thesis is focused on creation simplified 3D model, which includes pressure losses calculation, aproximation of data provided by outcomes of detailed 1D model and analysis of heat transfer during combustion process. Simulation results dealing with radiation heat transfer and heat conductivity are included in conclusion.
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Fluid grate design and optimalization in the function aspect point of view and economy of production
Voráč, Petr ; Vondál, Jiří (referee) ; Nekvasil, Richard (advisor)
The Master´s thesis deals with the fluid layer, with types of fluidized layer and with problems which can be solve during design of new fluidized beds. The aim was find the fluidized grid, which is the best form economical and technological point of view. In this work are compared three fluidized grids. The first was part of submission. Next two additional types were then proposed by the author of thesis. Proposals grids are discussed in detail from the design phase, through the modeling and subsequent simulation part in a computer program. The results of simulation are pressure losses. Which are compared with the recommended interval values. Afterward these tested beds are put through technical and economic analysis. The result is grade which is met both requirements.
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Computational modelling of a laboratory burner using FLUENT code
Broukal, Jakub ; Vondál, Jiří (referee) ; Hájek, Jiří (advisor)
Tato diplomová práce je zaměřena na porovnání různých turbulentních a chemických modelů na příkladu volné metanové trysky ústící do vzduchu. Nejprve je uveden teoretický úvod k modelům, následován CFD (Ansys Fluent) simulacemi plamene pomocí vybraných modelů. Jako součást práce je provedeno a vyhodnoceno experimentální měření. V závěru jsou experimentální výsledky porovnány s nasimulovanými daty.
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Ejectors and it's utilization in industry
Zejda, Vojtěch ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
This work aims at introducing ejector pumps. It describes the working principle, advantages and disadvantages and restrictions of their usage in various applications. Main disadvantage of ejectors is the low efficiency which limits the usage only in specific applications where it is not considered to be a crucial factor. Therefore, examples of usage of various ejectors in industrial processes are listed further. Last but not least, in these examples are also demonstrated difficulties and reasons why it is favourable to use an ejector rather than other types of pumps. Further off, this work deals with design methods of ejectors and compares their suitability. It appears that not all the methods are suitable for ejector design, because it depends greatly on presumed shape of a certain ejector. In the end, there is compared energy intensity of an ejectors and common centrifugal pumps and confirms energy disadvantage of ejectors.
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Local heating units for family house - case study
Nováček, Milan ; Touš, Michal (referee) ; Vondál, Jiří (advisor)
This thesis deals with selected methods of heating a house. The first part is dedicated to familiarization with the possibility of local heating of houses and the analysis of individual sources and heating equipment. The second part describes the designed family house. For this house were proposed some proposals by heating. The next step was to evaluate the individual proposals and select three that were assessed in terms of economic analysis. Economic analysis compared the start-up costs and operating costs. The proposals were compared with existing heating systems. At the end of the proposals was evaluated and determined the best method of heating the house.
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Heat flux calculation during boiling process – application for cooling of combustion chamber
Földváry, István ; Pačíska, Tomáš (referee) ; Vondál, Jiří (advisor)
There is a water-cooled combustion chamber at the Institute of Process and Environmental Engineering, which is used for testing of burners. Effective cooling is a particularly significant problem. It is also necessary to ensure accurate measurement of wall heat flux extracted by the cooling water. Therefore the main aim of the thesis is calculation of the minimum flow rate of cooling media required for safe operation of the combustion chamber. A comprehensive review of the heat transfer mechanisms was performed. Description is provided for the basic characteristics of phase changes with an emphasis on detailed analysis of mechanisms of boiling and evaporation. The presence of boiling at the water-side wall in the inner mantle was verified in the calculation part. Computation of the heat transfer coefficient was done by using the similarity methods. Temperature of the wall was then evaluated. A control on the presence of nucleate boiling was performed and the required minimum flow rate was determined for each section of the chamber.
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Design optimization of water-cooled thermocouple probe
Dohnal, Miloslav ; Vondál, Jiří (referee) ; Hájek, Jiří (advisor)
The object of this bachelor’s thesis is to create a computational model of an existing (basic) structure water-cooled thermocouple probe, to calculate and evaluate the quality of existing cooling probe and to propose possible design modifications to improve the cooling effect of the probe tip. Verify and evaluate design modifications by further calculation. The calculation will be carried out using computational fluid dynamics (CFD method). On the contrary, the aim of this work is not to create another text tool for students dealing with CFD topics. The first part describes the meaning and history of the CFD methods, then mentions the work on the principle of thermocouple probes and its application in practice. The second part of the work is devoted to problem solving. It describes the reason for the introduction of model situations when calculating the cooling effect of thermocouple probes and calculation indicates what type of flow occurs inside the thermocouple probe. It further describes the results of calculations for several approximations gradually increasing accuracy of the resulting solution of the problem and assessing the quality of cooling in the probe tip current (basic) structure. The final part deals with design changes for better cooling effect especially in the probe tip, which is verified by further calculation as well.
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Heating units for family houses - algorithm for selection
Reiter, Milan ; Vondál, Jiří (referee) ; Kermes, Vít (advisor)
This bachelor’s thesis deals with the ways of heating for family houses. In the first part of this thesis are described the heat sources. The heat sources are diveded by type of fuel. In the next part of this thesis is a decription of claims for installation the heating source, the use of various fuels and chimneys. In the next part are descibed claims of an operation the heating sources. The fourth part deals with the algorithm for selecting a source of heat. Here is a description of each step of algorithm, which we need for selection of suitable heat source. In the last part of my thesis is made a presentation of the algorithm performed on a model family home. There are selected six types of heating in the house. At the end is chosen one, most economical type.
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Small heating units - emissions - fuels - choice
Coufal, Martin ; Vondál, Jiří (referee) ; Kermes, Vít (advisor)
The first part of thesis focuses on an overview of small heat energy sources. Second part is an overview of available fuels and their related emissions. The third part is the creation of the basic algorithm to select the heat source. The last part is application of the proposed model to the virtual house Cesmína.
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