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Design of a closed cooling circuit
Novotný, Tomáš ; Milčák, Pavel (referee) ; Kracík, Petr (advisor)
The aim of this bachelor thesis is to design a closed cooling circuit for specific technologies of the power plant machinery room, namely lubricating oil system, power generator and high pressure hydraulic system. The main task is to provide heat dissipation from each system to a central heat exchanger, which is one of the objectives of the thesis design. The work is divided into three parts. The first part deals with the basic description of the cooling circuits and their division. In the second part, the basic components of the cooling circuit and their functions are presented. The principle of heat sharing is also presented. In the third part of the paper, the actual design of the closed cooling circuit is presented, which includes the design of the central heat exchanger. The work includes a model of the piping, which is based on a basic heat balance and P&ID diagram. AVEVA E3D software was used for its creation. Based on the piping isometry and pressure losses in the individual devices, the pressure loss of the circuit is determined. Another objective of the work is the design of the expansion vessel. The problem is solved by using software suitable for solving each part of the design. The output of the work is a refrigeration circuit meeting the requirements for the specified conditions.
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Analysis of Electrical Steel Additional Losses Caused by Stacking Holes
Kozlíček, Jiří ; Bílek, Vladimír (referee) ; Mrajca, Miroslav (advisor)
This bachelor's thesis deals with the analysis of losses in the electrical steel sheets of a distribution transformer, particularly the losses around stacking holes, which are used for stacking individual sheets during production. The thesis also includes standardized methods according to IEC 60404-2, 60404-3, and 60404-10, which can be used to determine the magnetic properties of materials used in transformers. Part of the thesis is the evaluation of the given issue using the finite element method, with the help of the Ansys program. Simulation models of 3 different types of sheets, which are commonly used in practice are designed in this program. The conclusion then focuses on quantifying the additional losses due to stacking holes, which is further discussed.
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Modern Cooling Concepts of Electrical Machines
Lukášek, Jan ; Cipín, Radoslav (referee) ; Toman, Marek (advisor)
The thesis focuses on the research of modern concepts of cooling of electrical machines. The first part of the thesis deals with the origin and calculation of losses causing heating of electrical machines. The second part describes the mechanisms of heat transfer and basic relations of fluid mechanics. The third part describes the basic principles of cooling of electrical machines. The final part of the thesis describes modern concepts and innovations in cooling systems for electrical machines described in the third part and separate modern innovations.
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Acceleration method of measuring electrical machines
Ředina, Ondřej ; Mach, Martin (referee) ; Červinka, Dalibor (advisor)
This thesis deals with the acceleration method of measuring electrical machines. The beginning of the work is dedicated to the description of standard loading methods, the description of the acceleration method and the analysis of losses in the electrical machine. Two speed modulations are selected: linear and sinusoidal. Each modulation requires a different procedure for determining the speed profile parameters. To apply the method, a diagram of the connection of the workplace is drawn and its optimization is carried out. Subsequently, the usability of the oscilloscope card is verified, which ensures the determination of the instantaneous frequency. Before the test itself, the moment of inertia is measured and the parameters of the speed profile are calculated. The acceleration method is supplemented by a full load test for a more detailed comparison of the results. The measured data almost coincide with the predicted values and trends.
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Evaluation of combine harvesters John Deere 670i and Claas Lexion 770
JURÁSEK, Martin
This bachelor thesis evaluates the John Deere 670i and Claas Lexion 770 combine harvesters in terms of cost, threshing quality, losses and area performance. The thesis describes the functions of the combine harvesters and their technological description and practical applications. The parameters calculated in the bachelor thesis are pre-harvest and harvest losses, area and weight performance, mass yield, travel speed, crushing quality, fuel consumption and fixed and variable costs.
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Switching loss reduction in the switch-mode supplies
Vašíček, Adam ; Vorel, Pavel (referee) ; Patočka, Miroslav (advisor)
The master's thesis covers in its first parts origins and consequnces of the switching losses, basic principles of the various resonant tanks and resonant DC/DC converters. Afterwards the innovative approach of the multiperiod modulation is presented. The main advantages of this kind of modulation include very wide zero current switching region and lowering the switching frequency as the output voltage decreases. In the remaining part of the thesis a prototype converter design is described.
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Energetic model of linear axis with ball screw and servodrive
Sládek, Vojtěch ; Tůma, Jiří (referee) ; Huzlík, Rostislav (advisor)
The aim of the thesis was to study the Energy Models of Linear Axes with Ball Screws and Servo Drives, to analyze the individual parts of the axis with respect to losses, the methodology of calculating the losses on the electrical part and the mechanical part of the drive and creating a complex algorithm that calculates the energy consumed for the specified motion. The thesis is divided into a theoretical and practical part, where the theoretical part is divided into the treatise on the electrical part of the axis and its losses and the part that deals with the mechanical part and its losses. The calculation is divided into the basic verification algorithm and the calculation on the given example. Each calculation is calculated for both linear acceleration and S-curve acceleration. For both types of acceleration, the result of energy and its course over time is also the waveforms of position, velocity, acceleration, angular acceleration, moments, powers, power, speed and currents over time.
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Calculation of optimum slip frequency of induction motor for minimisation of its losses
Bednařík, Václav ; Patočka, Miroslav (referee) ; Vorel, Pavel (advisor)
This master’s thesis focuses on the minimisation of losses by calculation of optimum slip frequency of induction motor. The next point of this master‘s thesis is supersaturation. Supersaturation must be solved for the size of losses, because of the effect that is cause of the losses, when current increases with saturation. However current is not increase proportionally with increasing saturation, but increases several times more. This problem is included in the calculation of the slip frequency. Optimum of slip frequency is solve for modified gamma model of induction machine. In the main point of this thesis is outlined the process, how the optimum can be found. With same process were already were found the equations, but they were too extensit. In the end is solved the optimum of slip frequency be minimum of the flux density.
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