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Calcination model developement for ANSYS Fluent
Anderle, Milan ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
The aim of the diploma thesis was creating a decarbonisation model of lime, implementation the model into CFD tool ANSYS Fluent and to test the decarbonisation model in a model of a real reactor. The required model was based on assumptions for a Shrinking Core Model (SCM). The main objective of this work was the non-catalytic conversion of substances and the search for the most used mathematical models for calcination. The CFD calculation, the sensitivity analysis and the Fluente parametric study were used. Data on the composition of gas flow, temperature, pressure and mass flow of limestone particles were selected for input variables. The particle model called Multiple Surface Reactions (MSR), which is a standard part of Fluent, was used at first. Subsequently, a UDF which was based on the SCM assumptions was written in the programming language C. The results of the CFD calculation were compared with the experimental values from the dissertation. It has been found that the MSR is sufficiently precise for calculation purposes but neglects the internal diffusion of CO2 through the CaO layer which forms behind the reaction front during calcination. It was found that it is possible to solve the flow with ongoing calcination without the need to know the parameters of the Arrhenian equation if the UDF is used. The created UDF incorporates the influence of intraparticular CO2 diffusion on the overall reaction rate.
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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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Materiální výukové prostředky ve výuce praktického vyučování
Hájek, Jiří
This bachelor's thesis is devoted to the topic of material didactic tools in the teaching of vocational training at the Polytechnic Secondary School in the field of carpentry. The theoretical part focuses on the essence, description and distribution of teaching aids in the implementation of teaching. It presents the didactic technique that the OV teacher has at his disposal and how the choice of an appropriate means will make the transmission of didactic information more effective. It secondarily helps create a positive relationship with the field of education, moves into the realm of intellectual and material heritage, and thus contributes to the development of humanity and future generations. The empirical part of the bachelor thesis contains research to determine the use of material teaching aids by pedagogues and their satisfaction with the current level of these aids. The second part of the research aims to compare the level of material teaching aids in education from the point of view of vocational training teachers compared to companies in the private sector. How familiar the students of this field are with the use and with which resources they can work according to the profile of the graduate.
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Transparent packing for optical experiments in Rotating packed beds
Hájek, Jiří ; Elcner, Jakub (referee) ; Malý, Milan (advisor)
Given the amount of energy and industrial processes that produce carbon dioxide, it is necessary to reduce the amount of CO2 emitted into the atmosphere. One option is to capture and store the carbon dioxide produced, called CCS (Carbon Capture and Storage). For effective capture, a rotating packed bed absorber can be used, which works on a similar principle to a static absorption column, but the driving force of the liquid is not gravity but centrifugal force. This allows the device to be very compact in size. To optimise the absorption process, it is necessary to analyse the nature of the flow inside the absorber. This work focuses on the design and testing of a unique packed bed with stainless steel wire filling and transparent plexiglass support parts for optical analysis of the internal flow. Using a high-speed camera, the nature of the fluid flow was recorded under different operating modes. The changed parameters were the operating speed, which ranged from 300 to 1,800 rpm, and the velocity of the fluid flow, ranging from 1.25 to 11.5 m/s. When evaluating the nature of the flow, attention was paid mainly to the inner part of the packing fill, where the droplet size and velocity change the most. However, the assessment of the flow across the entire packing was also evaluated. Recommendations for the choice of operating modes, evaluation of droplet size and, finally, the empirical correlation for the calculation of the absolute liquid velocity at the inner part of the packing is also discussed.
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Modeling of process and power equipment fouling by solid pollutants
Strouhal, Jiří ; Turek, Vojtěch (referee) ; Hájek, Jiří (referee) ; Jegla, Zdeněk (advisor)
Modelling of particulate fouling based on Computational Fluid Dynamics enables to detect a risk of deposit development and to propose improvements in operating conditions and equipment design. The work focuses on the transport and sticking of solid particles. The size of the particles lies in the range from several up to dozens of m. The conditions correspond to the deposition of particles with a negligible liquid fraction and the deposition occurs due to particle deformation, gravity, adhesion, wall surface roughness, deposit deformation and dynamic friction. An emphasis is put on the selection of a suitable sticking model from the group of critical velocity models, which aside from the local conditions and the particle properties account for the impaction velocity. Sensitivity studies on the model settings were conducted to assess the significance of the model parameters and the included phenomena. The simulations were conducted on the case of an experimental facility for solid fuels combustion. Obtained results were compared to observed deposits.
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Principles of open and closed kinematic chains and their usage in rehabilitation
Hájek, Jiří ; Kučerová, Klára (advisor) ; Kurková, Simona (referee)
Bakalářská práce Princip otevřených a uzavřených kinematických řetězců a jeho využití v praxi 7 Abstract The terms open (OKC) and closed (CKC) kinematic (kinetic - OKIC and CKIC) chain are very often used in physiotherapy. However, this view has a problem in defining the chains. In theoretical part, we focused on definitions according to individual authors, publications and studies that mention the terms. Because the terms OKC and CKC are perceived very differently in the literature and many authors have adapted them to their image. Based on the acquired knowledge, we find the view of the kinematic chains to be insufficient, inconsistent and thus confusing. In the work, we focused on processing as many resources as possible with the given issue. In the practical part, we used a structured questionnaire focused on therapists in clinical practice. We asked how they use the terms OKC and CKC (resp. OKIC and CKIC) and what experience do they have with the terms in their clinical practice. The aim was to find out: to description of which situations are these terms used for and how the terms are used in different kinesiological situations. To what extent are they used in accordance with the definitions or to what extent they differ from them. Based on the results of the questionnaire and the mentioned literature...
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Fine particles emitted from a heat source into the indoor environment
Hájek, Jiří ; Köbölová, Klaudia (referee) ; Pospíšil, Jiří (advisor)
This bachelor's thesis deals with fine particles emitted to indoor space during combustion in fireplace stowes. The beginning of work is focused on the description of biomass and its combustion. In the following part the pollutants, which are produced by combustion of bio-mass are mentioned, and last but not least is attention focused on current air quality in Czech Republic methods of measure of solid pollutants and measuring equipment. Calculation of concentration is closely described in the experimental part, and then the data, which was measured on different modes of operations of fireplace stowes, is presented.
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Development of computational tool for engineering
Komiš, Jan ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
The thesis aims to provide insight into the use of Python in engineering calculations. The thesis has been divided into a theoretical and practical part. The theoretical part introduces Python and its possible uses in the field of engineering. The second section of the theoretical part describes key choices of study resources and provides instructions on how to set up Python from the perspective of a common user. The final part of the thesis deals with the choice of appropriate libraries (SciPy, NumPy, Cantera, etc.) and shows how these can be used practically in specific tasks from the fields of thermomechanics and hydromechanics.
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