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CFD analysis of thermal stress of a tubesheet
Vince, Tomáš ; Babička Fialová, Dominika (referee) ; Rebej, Miroslav (advisor)
This diploma thesis focuses on the phenomena of multiphase flow in a steam generator as a one of probable causes of tubes and tubesheet weld cracking. In the first part of the work, a research was carried out focusing on the boiling and the phenomenon of two-phase flow in technical applications, its characteristics and properties. The thesis continuous with an overview of available numerical multiphase models in the ANSYS Fluent 2021 R1 and a research of previously published works focused on two-phase flow with the presence of boiling. The research is followed by a description of the particular boiler, which is part of the nitric acid production plant in the chemical company DUSLO, a.s., its operating conditions and a more detailed description of the issue that is being addressed in this thesis. The second part of the work continuous with a description of the computational model, including a description of the geometry of the model and used simplifications, the computational mesh and the description of boundary conditions. Important part is the description of calculation setting of steady-state and transient CFD simulations in ANSYS Fluent. Finally, the results of the two-phase flow calculation are presented and then discussed in the conclusions.
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Numerical study of classroom ventilation and its effect on the spread of harmful substances
Klusáček, Ondřej ; Prinz, František (referee) ; Elcner, Jakub (advisor)
The thesis deals with the numerical simulation of the effect of ventilation on the spread of pollutants in a classroom using the STAR-CCM+ program. The aim of the thesis was to create a realistic 3D model of the classroom, to select a suitable multiphase flow model, to evaluate the spread of pollutants under different forms of operation and to select the most efficient ventilation method. Using a Lagrangian multiphase flow model, the pollutant volume fraction was compared for each type of operation. The numerical solution was validated by means of an experiment carried out in identical rooms and under the same ventilation conditions. The resulting temperature and velocity fields in the classroom are also presented in the paper. Mechanical ventilation was found to be the most effective of the chosen methods. If the infected individual sits closer to the windows or doors, there is a lower risk of infection in the room
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CFD analysis of thermal stress of a tubesheet
Vince, Tomáš ; Babička Fialová, Dominika (referee) ; Rebej, Miroslav (advisor)
This diploma thesis focuses on the phenomena of multiphase flow in a steam generator as a one of probable causes of tubes and tubesheet weld cracking. In the first part of the work, a research was carried out focusing on the boiling and the phenomenon of two-phase flow in technical applications, its characteristics and properties. The thesis continuous with an overview of available numerical multiphase models in the ANSYS Fluent 2021 R1 and a research of previously published works focused on two-phase flow with the presence of boiling. The research is followed by a description of the particular boiler, which is part of the nitric acid production plant in the chemical company DUSLO, a.s., its operating conditions and a more detailed description of the issue that is being addressed in this thesis. The second part of the work continuous with a description of the computational model, including a description of the geometry of the model and used simplifications, the computational mesh and the description of boundary conditions. Important part is the description of calculation setting of steady-state and transient CFD simulations in ANSYS Fluent. Finally, the results of the two-phase flow calculation are presented and then discussed in the conclusions.
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