|
|
Cooling Concepts in Power Electronics
Hőhn, Matěj ; Súkeník, Jakub (referee) ; Toman, Marek (advisor)
This bachelor thesis deals with cooling concepts in power electronics and experimental measurements of thermal resistances in two different fan-cooled heat sink samples. In the first part of the thesis, calculations of losses in semiconductor switching devices are described. These are losses due to current conduction and switching between operating states. Then the basics of heat transfer theory such as conduction transfer, convection transfer, radiation transfer, and thermal-electrical analogy are described. In the third section, the procedure for calculating the required thermal resistance of the heat sink is described. Then, cooling concepts in power electronics are described, which include basic types of heat sinks, fan-cooled cooling and its operating characteristics, heat pipes, thermoelectric cooling and the use of liquid systems, such as cold plates and boiling liquid cooling. The last part of the thesis describes the preparation of a laboratory workstation for measuring the thermal resistance of two different fan-cooled coolers and comparing the measured results.
|
|
|
Sleep quality depending on room environment
Veličková, Kateřina ; Pokorný, Jan (referee) ; Fišer, Jan (advisor)
The aim of this diploma thesis was to determine the thermal resistance of selected sleep assemblies (clothing, mattress, blanket, pillow) using measurements with a thermal manikin and subsequently to determine the appropriate ambient temperatures at which a balanced thermal equilibrium between the sleeping person and their environment would be maintained. Four different assemblies were selected for measurement purposes, differing in the type of blanket used (summer blanket, quilt, cover, and no blanket). The influence of the thermal manikin's position on the measured value was also investigated. It was proven that the influence of position on the overall thermal resistance is negligible, with measured values ranging from 1.12 clo (assembly without a blanket in the side position) to 2.05 clo (assembly with a summer blanket in the back position). Subsequently, appropriate ambient temperatures were determined using the PMV model, which ranged from 24.4 °C to 28.6 °C. The two-node model proved to be insufficiently sensitive for the addressed issue, and the heat flux maps derived from the equivalent temperature model were not calibrated for sleep but for mild activity while seated. Nevertheless, they provided interesting information about the perception of thermal comfort in different parts of the body.
|
|
|
Study of the thermal insulation effect of thermally reflective insulations
Skříček, Darek ; Vala, Jiří (referee) ; Čermák, Jan (referee) ; Šťastník, Stanislav (advisor)
The dissertation on the topic Study of the thermal insulation effect of thermally reflective insulations is focused on the issue of measuring the thermal resistance R of thermoreflective insulations and determining the most suitable layer with the best thermal insulation properties. By measuring thermoreflective insulations on the Hot-Box measuring chamber, it was proven that higher values of thermal resistance R are always achieved with aluminum foil, which has the highest possible reflection of the radiant component of heat, i.e. the lowest possible emissivity on the surface. For this reason, the reflectance was measured on the Mid-IR Integrat IR ™ measuring apparatus. To study the thermal insulation effect of thermoreflective insulations, ten samples of these insulations with different compositions of aluminum and bubble foils are used to measure the insulation properties. The suitability of using thermoreflective insulation for building insulation was proven by measuring these foils.
|
|
|
Database of typical clothing for cabin of cars
Toma, Róbert ; Pokorný, Jan (referee) ; Fišer, Jan (advisor)
In this bachelor thesis, there are processed databases of typical clothing for cabin of cars. Data are based on information from survey for both women and men for three seasons – summer, transitional season and winter. There are mentioned factors which affect thermal comfort and thermoregulation of human body. The thesis includes options how to measure thermal comfort and how we can evaluate results on different scales. Next, I process the way how we measure thermal resistance of each databases of clothing. Measurements are placed in climate chamber in VUT Brno and we are using manikin Newton made by Measurement technology Northwest. In the end, we mention some results and comparison of both genders.
|
|
|
Cooling of a powerful light source
Tulis, Vojtěch ; Tuhovčák, Ján (referee) ; Hejčík, Jiří (advisor)
The diploma thesis is focused on calculating the thermal resistance of the line light source and the design of the cooling system with ideal inlet temperature. The partial aim of the work is in cooperation with CAMEA spol. s r. o. to determine the thermal resistances of the individual parts of the device and propose modifications so that the total thermal resistance and the maximum temperature are within the limits given by the cooperating firm. The main objective is to design a cooling system with all safety features and recommended regulation for economical and reliable operation. Analytical calculations, CFD simulations and real-world testing are used to determine the desired results. A reduction by 30% in thermal resistance of the printed circuit board was achieved, the thermal resistance of the aluminum profile with the cooling channel was determined and its hydraulic properties were calculated. The current cooling system designed by CAMEA spol. s r. o. for less powerful diodes was verified for use in a more powerful system, and a new cooling system was designed for efficient and economical operation in a powerful diode system.
|
|
|
Calculation of thermal resistance of finned heatsink
Kyanka, Radim ; Huták, Petr (referee) ; Toman, Marek (advisor)
This bachelor's thesis is focused on the problem with analytical calculations needed to define thermal resistance of finned heat sinks. First it describes how temperature proceeds at different boundary conditions at fin tip. Than it describes different mechanisms of heat transfer, equlation of heat resistance especially of natural and forced convection. To verify the results there is comparison between analytical equlations written in Matlab program and measuring results.
|
|
|
Study of thermal resistance of reinforced wood members
Janoušek, Radek ; Krbila, Jaromír (referee) ; Vaněrek, Jan (advisor)
This bachelor's thesis studies the problem of thermal resistance of a system consisting of timber as a structural member with external strengthening in the form of carbon fibre reinforced polymer lamellas connected by various types of adhesives. Attention will be paid to the thermal resistance of reinforced timber members with subsequent mechanical load.
|
|
|
Primary School
Forman, Daniel ; Manová, Ludmila (referee) ; Maceková, Věra (advisor)
Thesis Theme is a primary school, namely the outbuilding primary school Havlíčkův Brod, Konečná 1884. I suggest first grade pavilion and pavilion with school canteen with kitchens. Pavilions are based on the footings. Pavilions are designed as a two-way system from the wall HELUZ. Construction of ceiling are from ferroconcrete slabs are cross reinforced, single-layer roof is flat with a classic sequence of layers. In addition to construction and process layout I solved also the statics of building in specialize of concrete structures. The following are also evaluated heat and acoustic requirements and requirements for fire safety of buildings. New pavilions are solved as wheelchair accessible. Pavilion of the first grade has two floors with 5 classes of stem, 1 vocational and 2 classes are earmarked for after-school clubs. This pavilion is connected to the connecting neck between the former pavilon A and pavilion B. Dining pavilion has one floor, which is divided in the school canteen and kitchen is connected to the connecting neck leading to the gym. The land is mildly sloping to the south side. All consstructions comply with the applicable standards and recommendations ČSN.
|
|
|
Optimization of the printed circuit board for power LED
Schenk, David ; Klíma, Martin (referee) ; Ing. Josef Vochyán, Ph.D., ALCZ Jihlava (advisor)
This diploma thesis deals with the problems of heat transfer on printed circuit boards. The first part consists of a theoretical analysis of the principles of conduction of heat in different environments, comparing the properties of common type’s base materials for PCBs in terms of thermal properties and focuses on heat transfer from the chip. In the following part they are general information about the program ANSYS ® Workbench ™. Next part consists of the basic designs of PCBs and their improving. PCBs thermal properties for different configurations are verified with calculations, simulations and practical measurements. In the last part there are created design recommendations for PCBs design based on the comparison of the results of initial proposals and proposals to improvements.
|
|
|
Design of synchronous linear motor thermal network
Čech, Jan ; Toman, Marek (referee) ; Knebl, Ladislav (advisor)
The first part of this thesis deals with the study of linear motors. The introduction of the thesis deals with the brief description of the linear motor, including its accessories. This part explains principle of linear motors, their general advantages and disadvantages. The next section contains an overview and division of the currently used linear motors. The second part deals with the theoretical description of forms of heat transfer. The third part of the thesis deals with the design of an equivalent thermal circuit model of a linear iron-core linear motor with permanent magnet. Hereafter, the proposed design will be used to calculate the temperatures of the individual motor units. The temperatures are later compared with the results obtained with finite element method.
|
guest ::
