|
|
Optimization of Cooling Synchronous Machine
Makki, Zbyněk ; Rafajdus,, Pavol (referee) ; Kačor,, Pavol (referee) ; Janda, Marcel (advisor)
The main goal of doctoral thesis is optimization cooling of the synchronous machine. Problem is solved based on the finite element method with use of ANSYS software. Work is built up from theoretical part where is comparison of base equations for heat transfer and simulations for several models. Next part shows us two methods how simulate free and force convection. Depends on the better method from the previous two methods is used for next calculations with several algorithm which are used for find of best parameters for synchronous machine. Our control parameter is mass flow rate.
|
|
|
Computational Modeling of Turbulent Swirling Diffusion Flames
Vondál, Jiří ; Klemeš,, Jiří (referee) ; Tuček,, Antonín (referee) ; Hájek, Jiří (advisor)
Schopnost predikovat tepelné toky do stěn v oblasti spalování, konstrukce pecí a procesního průmyslu je velmi důležitá pro návrh těchto zařízení. Je to často klíčový požadavek pro pevnostní výpočty. Cílem této práce je proto získat kvalitní naměřená data na experimentálním zařízení a využít je pro validaci standardně využívaných modelů počítačového modelování turbulentního vířivého difúzního spalování zemního plynu. Experimentální měření bylo provedeno na vodou chlazené spalovací komoře průmyslových parametrů. Byly provedeny měření se pro dva výkony hořáku – 745 kW a 1120 kW. Z měření byla vyhodnocena data a odvozeno nastavení okrajových podmínek pro počítačovou simulaci. Některé okrajové podmínky bylo nutné získat prostřednictvím dalšího měření, nebo separátní počítačové simulace tak jako například pro emisivitu, a nebo teplotu stěny. Práce zahrnuje několik vlastnoručně vytvořených počítačových programů pro zpracování dat. Velmi dobrých výsledků bylo dosaženo při predikci tepelných toků pro nižší výkon hořáku, kde odchylky od naměřených hodnot nepřesáhly 0.2 % pro celkové odvedené teplo a 16 % pro lokální tepelný tok stěnou komory. Vyšší tepelný výkon však přinesl snížení přesnosti těchto predikcí z důvodů chybně určené turbulence. Proto se v závěru práce zaměřuje na predikce vířivého proudění za vířičem a identifikuje několik problematických míst v použitých modelech využívaných i v komerčních aplikacích.
|
|
|
Developement of In-Line Heat Treatment Methods
Hnízdil, Milan ; Štětina, Josef (referee) ; Pospíchal, Miroslav (referee) ; Raudenský, Miroslav (advisor)
In-line heat treatment is a part of technological process uses a phase and structure changes to obtain required mechanical properties. Heat treatment of rolled products offers a reduction of steel making costs and a creation of new steel products. For example the TRIP steel is a part of modern steels which is used in the automobile industry for higher safety of passengers. The heat treatment is often described in the literature. But the authors are often focused on the method how to get the required structure and mechanical properties for different metallic materials. Nevertheless just few articles are focused on the technical observing of temperature regimes and which parameter is necessary to consider during designing the cooling section. Eight parameters were tested by the experimental way to examine their influence on the cooling intensity. They were: gravity (orientation of the cooled surface), coolant pressure, amount of coolant spraying on the surface (the flow rate), rolling velocity, nozzle configuration, kind of nozzles (full cone or flat fan nozzle), coolant temperature and the surface quality (surface roughness and scales). All these parameters have an influence the heat transfer coefficient. Based on knowledge gained in this work was created the cooling section, which comply with the required cooling temperature regimes.
|
|
|
Developement of In-Line Heat Treatment Methods
Hnízdil, Milan ; Raudenský, Miroslav (advisor)
In-line heat treatment is a part of technological process uses a phase and structure changes to obtain required mechanical properties. Heat treatment of rolled products offers a reduction of steel making costs and a creation of new steel products. For example the TRIP steel is a part of modern steels which is used in the automobile industry for higher safety of passengers. The heat treatment is often described in the literature. But the authors are often focused on the method how to get the required structure and mechanical properties for different metallic materials. Nevertheless just few articles are focused on the technical observing of temperature regimes and which parameter is necessary to consider during designing the cooling section. Eight parameters were tested by the experimental way to examine their influence on the cooling intensity. They were: gravity (orientation of the cooled surface), coolant pressure, amount of coolant spraying on the surface (the flow rate), rolling velocity, nozzle configuration, kind of nozzles (full cone or flat fan nozzle), coolant temperature and the surface quality (surface roughness and scales). All these parameters have an influence the heat transfer coefficient. Based on knowledge gained in this work was created the cooling section, which comply with the required cooling temperature regimes.
|
|
|
Design of heat exchanger for feeding heat water network 5,5 MW
Kubíček, Ondřej ; Moskalík, Jiří (referee) ; Baláš, Marek (advisor)
The Master thesis deals with the water-heater design for heat-exchange station with total power output 5,5 MW. The goal of the thesis is to make thermal and hydraulic calculation in the extent of the assignment and to develop a projection drawing of the heater along with a correct dimensioning of the shell and flanges. Thesis goals were met according to the assignment. The introductory part of the thesis briefly introduces to the heat-exchanger problematic and selected topics about heat-transfer. Following the basic mass and energy flows calculation inside the heater together with the thermal and hydraulic design determines the size of the heat transfer surface of pipes. After that the design calculations were made, whose results are used to determine the basic dimensions of selected parts and checking the accuracy of designed dimensions. In the last part of the work the design process is more described also with a more detailed description of selected parts.
|
|
| |
|
|
Computational Model of KWH Boiler
Koiš, Jiří ; Skála, Zdeněk (referee) ; Lisý, Martin (advisor)
The subject of this thesis is the computational model of existing KWH boiler. There is a short research in the introduction, which deals with combustion heat of considered boiler. The stoichiometric and balance calculations of gasification chamber ZKG are performed first. The Balance calculations are based on the boiler thermal loss calculations, the losses were determined experimentally. The entire calculation is processed in a computational program for purposses of debugging and manipulation with partial calculations. The computational model that is proposed in this thesis provide better boiler proces understandig. The real boiler measurement is performed for evaluation. The next point is the result analyses, that shows potential boiler efficiency improvements.
|
|
| |
|
|
Tubular minichannel heat transfer coefficient measurement
Snášel, Jan ; Kamenský, Petr (referee) ; Hejčík, Jiří (advisor)
The master’s thesis is describing measurement of heat transfer coefficient for heat exchanger with tubular minichannels. For understanding of the process, basic theory of heat transfer has its part in this work. The advanteges of minichannels and their clasiffication are also stated here. Another part describes the calculation for determination of heat transfer coefficient using the Wilson plot method and the method of direct determination of heat transfer coefficient. Measurement data are evaluated and comparison is made for results of both methods. This results are used for formulation of correlation equation for given flow regime.
|
|
|
Stirling engine 3kW combustion chamber
Matuška, Petr ; Zháňal, Lubor (referee) ; Kaplan, Zdeněk (advisor)
This thesis deals with the construction proposal of the combustion chamber of Stirling engine. The introduction briefly describes the history and practical application of Stirlinova engine today. The following section explains the differences between theoretical and real cycle and the principle of beta Stirling engine modifications. The next section is devoted to the calculation of fuel and air consumption and fuel compared to each other. The proposed design is based not only on the calculation of fuel and air, but also heat transfer between flue gas and preheated air. The last part is devoted to calculating the flow of LPG and flow model of the combustion chamber.
|
guest ::
