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Heat exchanger using structured material
Simon, Jakub ; Čížek, Petr (referee) ; Vaverka, Ondřej (advisor)
The aim of this work was to develop and describe a design method of a heat exchanger using Triply Periodic Minimal Surfaces (TPMS) structures and to validate it by design, fabrication, and experimental testing of a working sample. It is an oil-water cooler fabricated additively by Laser Powder Bed Fusion on an SLM 280 HL machine from AlSi10Mg material. After a series of analyses and tests, a cubic diamond structure with a minimum wall thickness of 0.7 mm and a range of relative densities of 15 to 25 % (cell edge length 11.1÷18.5 mm) was chosen for the developed method. The method also includes a prediction script of the performance of the proposed heat exchanger, which was created from data measured during testing of samples with different cells configurations. The method itself guides the user step-by-step from the selection of input requirements, through the estimation of performance, to the two-step parametric modelling of the TPMS exchanger itself (explicit and implicit). The functional sample created using this method achieved heat flows of 315,25 W, which is 4.2 % higher than the reference plate exchanger. The TPMS exchanger also has a 78 % smaller heat transfer body and 62 % less total mass. The differences between predicted and actual heat flows were up to 18%. In its current state, the method is suitable for the design of TPMS heat exchangers with heat flow of 50 to 230 W. However, it is generally versatile and can also be used to map other areas, thus making it more accurate.
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Influence of some microbiogenic elements on carotenogenic yeasts
Pulkrábek, Josef ; Holub, Jiří (referee) ; Obračaj, Jan (advisor)
Carotenogenic yeasts of the genus Rhodotorula are well known for their production of a variety of economically valuable and otherwise difficult to produce compounds such as fatty acids, carotenoids, ergosterol, and ubiquinone. This study investigates the effect of the addition of select microbiogenic elements (Fe, Se, I) and their combinations into mineral cultivation media on the production of the mentioned valuable metabolic products and the rate of element sorption into the biomass of the strains of Rhodotorula mucilaginosa, Rhodotorula kratochvilovae, and Rhodotorula toruloides. Additionally, the sorption of zinc oxide, ferrous fumarate, and selenomethionine into previously cultivated biomass was measured with sorption times of 2 and 24 hours. Fatty acid content was determined using GC-FID, while carotenoids, ergosterol, and ubiquinone were analyzed using HPLC-DAD, with element content being quantified using ICP-OES and IC. With a few exceptions, the production of metabolic products was decreased with the addition of elements into the media and inversely correlated with their concentration. Higher concentrations generally showed greater absolute amounts of sorbed elements but lower relative amounts, which, combined with reduced production of metabolic products shows that the media are not ideal for the cultivation of the given species. The elemental contents were such that biomass supplemented with individually sorbed elements would vaguely align with ESFA dietary reference values, but cultivation in media with a mixture of added elements could result in the biomass containing either insufficient iron or excessively high levels of selenium. Sorption levels were relatively low (5 to 22 % for iron and 0.5 to 2.5 % for selenium). Indicating that cultivation in media with lower concentrations of elemental additives is a promising area for future research.
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Testing of sliding coatings for space applications
Velička, Jan ; Pouzar, Josef (referee) ; Košťál, David (advisor)
This bachelor thesis deals with sliding coatings for use in space applications. In the experimental part, the number of cycles to wear for a molybdenum disulfide based coating was investigated. This coating was deposited on a beryllium copper CuBe substrate. The coating was tested for its possible application to bolt threads. The coefficient of friction of all samples was measured on a tribometer in an atmospheric environment. The specimens were loaded with a normal force of 35 N during the measurement. The number of cycles to wear was compared for specimens differing in coating time. The number of cycles was found to be similar for lower coating times. Then the number of cycles to wear started to increase with the coating time. From the findings, it can be said that increasing the coating time increases the coating life. Such a coating is suitable for the protection of bolts against galling.
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Exhaust Temperature Stabilitation Systems for Turbocharged Engines
Böhm, Michael ; Charvát, Pavel (referee) ; Vondrák, Adam (referee) ; Štětina, Josef (advisor)
This paper describes the possibilities of reducing temperature pulsations in the exhaust manifold of an internal combustion engine. For this purpose, the concept of a heat reservoir with a phase change material that can store the heat generated in the exhaust manifold is chosen. At a temperature lower than the phase change temperature of this material, the heat storage is then able to transfer the heat back to the exhaust gas, thereby reducing the temperature pulsations. The actual design consists of an advanced heat storage design consisting of an assembly of smaller tubes that increase the heat output of the storage while causing minimal pressure drop in the exhaust manifold. This concept is validated and compared with a series engine without a stack through simulations in both 1D and 3D computing environments. The designed and constructed prototype stack is subjected to experimental testing to confirm its performance. The effects of the electrically assisted turbocharger on the exhaust gas temperature are also analyzed. Finally, all the results are summarized showing the overall potential of this system and a possible way forward in the development of these stacks with phase change materials is outlined.
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Fire of batteries in electric vehicles
Blažek, Štěpán James ; Sitek, Tomáš (referee) ; Preisler, Lukáš (advisor)
This bachelor thesis deals with the causes and formation of fires in electric vehicle batteries. The first part summarizes the theory related to types of batteries, used materials, and reviews the phenomenon known as Thermal runaway. The second part of the thesis describes the burning of electric vehicles, providing basic categorization of fire occurrence in electric vehicles and the phenomena accompanying them. The statistical comparison of the current and future development of the number of fires in electrically powered vehicles in the Czech Republic compared to conventional combustion engines, data analysis, and recommendations are summarized in the final part of the bachelor thesis. From the given statistics, it is evident that an electric vehicle is less likely to catch fire, however, it is acompanied by the release of hazardous gases, creating a significant challange in terms of fire extinguishing.
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Logging of vehicle's position by a differential GPS with base station
Vala, Matěj ; Repka, Martin (referee) ; Straka, Tomáš (advisor)
The present work deals with the study of GPS, differential GPS and GPS with base station. The research focuses on the functioning, present status and future development of these systems. Further the thesis presents the actual measurement of the vehicle route using different GPS system. Base station, experimental vehicle, ADMA-G-PRO+, RT3000 and conventional GPS devices were used for the route measurement. The measurements were performed with and without correction. The analysis of the measured data was carried out in Matlab software in TeleMatrix, focusing on different parameters for each GPS system. The first analysis evaluates the route measurements using three GPS systems (RT3000, ADMA-G-PRO+ and a conventional GPS device). The results obtained show the effect of signal quality, horizontal speed, number of satellites, vehicle orientation, heading standard deviation and accuracy status during normal driving and during specific runs for the different GPS systems. The second analysis evaluates the RT3000 with and without correction for different manoeuvres. The evaluated results show that the RT3000 with correction provides higher accuracy than the RT3000 without correction. The RT3000 with correction shows a lower standard deviation of heading in the range of 0.210° - 2.228°, confirming its higher accuracy compared to the RT3000 without correction, where the standard deviation of heading ranges from 0.384° - 4.418°.
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Optimizing a highly loaded components for motorsport
Šišpera, Petr ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis deals with optimizing the rear suspension of the fifth generation Honda Civic for motorsport application. The goal is to reduce weight while increasing stiffness and precision in wheel control. The work is based on the properties of serial components, which are analyzed using FEM analysis in the Ansys program. Load conditions are calculated from vehicle dynamics and the loading of individual arms from the suspension kinematics. Suspension components are first modeled and analyzed and this data provides input information for optimization. Individual components are initially topologically optimized, based on which models are created for deformation stress analysis. The properties of the serial parts are ultimately compared to optimized ones under the most critical loading conditions and the result of the work is an optimized suspension system with lower weight and higher stiffness.
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Efficient Instrumentation of Programs using LLVM Framework
Hucovič, Vladimír ; Vojnar, Tomáš (referee) ; Pavela, Jiří (advisor)
Cílem této práce je vyvinout nový, efektivní profilovací nástroj, který rozšiřuje sadu nástrojů Perun, která je zaměřena na systematické a dlouhodobé monitorování výkonu softwarových projektů. Nový nástroj je založený na technice instrumentace při překladu, s využitím API systému Pass Framework, který je součástí projektu LLVM. Implementovaný profilovací nástroj sbírá počet vykonání základních bloků v programu. Několik optimalizačních technik, jako je inlining instrumentačního kódu nebo analýza grafu toku řízení funkcí, bylo využito pro snížení profilovací režie tohoto nástroje. Výkon nástroje byl vyhodnocen na dvou projektech a experimenty ukázaly, že jeho profilovací režie je nižší než režie některých existujících open-source nástrojů.
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Wind potential in the conditions of the Czech Republic in the lower atmosphere
Sedláček, Jakub ; Škorpík, Jiří (referee) ; Linda, Jakub (advisor)
The presented bachelor thesis deals with online wind potential simulation tools, specifically the accuracy of their estimation through Weibull curves. For comparison, data from measuring stations exclusively focused on the lower atmosphere are used. The first part of the paper explains the wind, its characteristics and other important concepts for a better understanding of the topic. The following part is devoted to wind maps and models used for their construction. In the last part, the simulation tools are compared with actual measured data and their accuracy is evaluated. Based on this accuracy, the result of this work is finally assessed.
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Design of Direct Mount B-Knuckle for Bicycle Derailleur
Chalupa, David ; Strecker, Zbyněk (referee) ; Košťál, David (advisor)
This bachelor thesis focuses on optimizing the shifting mechanism of mountain bikes by eliminating inaccuracies caused by the use of a replaceable hanger. The aim was to design, manufacture, and test an adapter enabling direct attachment of a mechanical derailleur to the mountain bike frame. The essence of the work lies in utilizing 3D printing to produce mechanically stressed components. Within the project, two adapter designs were introduced: the first optimized for production using 3D SLS printing technology with the intention of commercial sale, while the second adapter is tailored for production on home 3D printers. Both adapters were designed using generative design based on analyzed loads. The outcome of the work is two fully functional adapter solutions. Testing revealed that the adapter manufactured using SLS printing technology from PA12 material exhibited a 24.8% increase in stiffness and a 2.85% decrease in weight compared to a derailleur attached using a hanger. The adapter produced using FDM technology from ASA material achieved a stiffness increase of 127.5% and a weight reduction of 2.3%.
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