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Micronization of biopolymer material
Gistingerová, Radka ; Wikarská, Monika (referee) ; Pospíšilová, Aneta (advisor)
This bachelor thesis focuses on the preparation of poly(3-hydroxybutyrate) microparticles for cosmetic products. The particles were prepared by emulsion technology, where a chloroform solution of poly(3-hydroxybutyrate) was dispersed in an aqueous solution of polyvinyl alcohol. The original poly(3-hydroxybutyrate) was also in powder form, but it was thought that its properties could be improved by this treatment. Evaporation of all the chloroform produced poly(3-hydroxybutyrate) particles. By changing the input concentrations of the two components, the particle size distribution was altered. All prepared powders were measured using a scanning electron microscope and measured by laser diffraction. Experiments and subsequent measurements showed that increasing the concentration of the emulsifier solution leads to an overall decrease in particle size, whereas a higher concentration of poly(3-hydroxybutyrate) causes an increase in particle size. To evaluate the potential of the prepared particles in cosmetics, all powders were evaluated sensorially. The evaluators observed almost no differences between the powders, only the original poly(3-hydroxybutyrate) powder was rated slightly worse compared to our prepared powders. The powder that is currently used in cosmetic products was rated very similarly to the powders that were prepared by emulsion technology.
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Methods for liquid-gas separation
Matoušek, Jakub ; Touš, Michal (referee) ; Vondra, Marek (advisor)
This diploma thesis is devoted to the separation of liquid from gas. Functional principles and methods for the separation of droplets from the gas phase stream are presented in the introductory part. The research also lists the types of separators and mist eliminators, including their advantages and disadvantages. Cyclone separators are described in detail in the thesis in terms of the separation principle, design and factors influencing the efficiency of separation. The experimental activity took place on salt water and dealt with finding the optimal operating conditions for a cyclone with a given geometry using the method of Design of experiments (DOE). The vapor-liquid mixture generated in the evaporator entered the cyclone and the effect of salt concentration and inlet flow rate on the separation efficiency and pressure drop of the cyclone was investigated. Experimentally, the highest efficiency of 97.22% was achieved at a flow rate of 8.59 kg/h and with a salinity of water supplied to the evaporator of 14,246 µS/cm. The quality of the distilled water was therefore 5 µS/cm. Without the inclusion of a cyclone, the conductivity of the condensed steam would correspond to 175.31 µS/cm. In the final part, a proposal for modifications of the tested equipment was presented to improve the separation efficiency within the evaporator technology.
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Optimization of EDM process control parameters
Prokeš, Tomáš ; Beneš, Libor (referee) ; Bednář, Josef (referee) ; Matoušek, Radomil (advisor)
The dissertation thesis is focused on the optimization of control parameters of an EDM machine; the subject of optimization is cutting speed and surface topography. The first part of the thesis contains a research study on the technology of electrical discharge machining with the attention paid to the optimization methods use for control parameters of this process. The second part of the thesis is focused on real application of knowledge gained from studied sources. Here, a design of experiment aim at optimizing the parameters of the EDM machine is designed and carried on to maximize the cutting speed with the highest possible surface quallity. The result of the work is to build adequate regression models and find the optimal setting of machine control parameters.
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THEORETICAL PROPERTIES AND APPLICATIONS OF ADVANCED DESIGNS OF EXPERIMENT
Hrabec, Pavel ; Hlávka,, Zdeněk (referee) ; Kraus, David (referee) ; Bednář, Josef (advisor)
The methodology of the design of experimnet has become an integral part of the optimisation of manufacturing processes in recent decades. Problems regarding designs of experiments are still up to date, especially because of a variety of approaches to collecting and evaluating data. Scientists in different research and development areas often do not take into account possible shortcommings or even essential assumptions of selected design and/or its evaluation methods. This disertation thesis summarizes theoretical bases of selected designs of experiments. Describes several applications of central composite design on responses regarding wire electrical discharge machining process. And compares different designs of experiment for response surfaces of five parameters with regards to algoritmic selection of statistically signifficant parameters.
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Volumetric accuracy of machine tools
Máčala, Daniel ; Marek, Tomáš (referee) ; Holub, Michal (advisor)
The diploma thesis deals with the influence of the volumetric accuracy of the machine tool on the size of the assessed work space. The impact assessment was carried out on the basis of tests of a three-axis vertical CNC machining center. The thesis is divided into two parts, theoretical and practical. The theoretical part is focused on geometric / volumetric accuracy of machine tools, measuring technique for measuring geometric errors and Design of Experiment. In the practical part, there is an analysis of the Design of Experiment according to Shainin, description of the work with the measuring instruments and the measurement of the geometric / volumetric accuracy of the machine including statistical evaluation. The output of the thesis is the description of the influence of volumetric deviation on the size of the measured work space by means of statistical methods.
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Equipment for Thickening Waste Water from Biogas Plants
Vondra, Marek ; Bébar, Ladislav (referee) ; Hoffman,, Pavel (referee) ; Stehlík, Petr (advisor)
This dissertation thesis deals with the development of technology which could tackle two major issues related to biogas plants. These issues concern the insufficient use of waste heat from biogas combustion and its subsequent processing. It also concerns the use of the fermentation residues which are formed in large quantities and whose use is restricted by law. Based on a literary search of separation methods, a vacuum evaporator was selected as the most suitable technology. Its advantages include its simple construction, operational reliability and robustness, low costs of thickening medium pre-treatment, potential for a quick commercial application and, especially, the chance to use a low-potential waste heat. A primary purpose of this technological unit is the reduction in the volume of fermentation residues. Other benefits include the efficient use of waste heat from a biogas plant, which would otherwise be wasted. Evaporators with a low consumption of electrical energy (which is a main product of a biogas plant) seem to be the best option for applications in the biogas plants. Three of these technologies were subjected to a more thorough analysis, which included the development of computational models and their quantification for conditions in a sample biogas plant. A one-stage evaporator with a forced circulation (680 – 712 kWhth/m3, 25.9 – 30.5 kWhel/m3) was evaluated as the least suitable option in terms of energy demands. The energy intensity of a three-stage evaporator with a falling film (241 – 319 kWhth/m3, 12.0 – 23.6 kWhel/m3) and a nine-stage flash evaporator (236 – 268 kWhth/m3, 13.6 – 18.4 kWhel/m3) is significantly lower. A multi-stage flash evaporator (MSF) was then chosen for development and will form the central focus of this thesis. The reasons for the choice are as follows: the low requirements on the heat transfer surface, good operational experience in the field of desalination, its simple construction, modularity and evaporation outside the heat transfer surface. A thorough technical-economic evaluation was also performed on the integration of the evaporator into the biogas plant. The main part of the work included the experimental development of a MSF evaporator prototype. The main objective of this development was to achieve a stable flow rate of the thickening liquid digestate fraction and the continuous formation of the distillate. This was not an easy objective to achieve, especially due to the properties of the liquid digestate, which has a non-newtonian characteristic and increased density and viscosity compared to water. The tendency of the liquid digestate to form foam was also the subject of analysis. The development of the evaporator and first successful operational test are described in the thesis in detail. This required the use of an anti-foaming product. A fully-developed prototype of the MSF evaporator allowed us to achieve continuous operation with a distillate production, reaching from 5 to 10 kg/h at a liquid digestate flow rate of 0.4–0.5 m3/h. The main drawback of this technology is the pollution of the distillate with ammonia nitrogen, and it is for this reason that the basic procedures of its subsequent elimination was selected for further analysis.
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Design of Experiment
Holec, Tomáš ; Popela, Pavel (referee) ; Bednář, Josef (advisor)
In this thesis, the design of experiment is studied. Firstly, a theoretic background in mathematical statistics necessary for understanding is built (chapter 2). The design of experiment is then presented in chapters 3 and 4. Chapter 3 is divided into several subchapters in which its brief history is provided as well as its complex theoretic description (basic principles, steps for planning, etc.). Chapter 4 deals with particular types of the design of experiment (Factorial experiments or Response surface design). Simple examples are provided to illustrate the theory in chapters 3 and 4. Last part of the thesis is strictly practical and focuses on an application of the theory for particular data sets and its evaluation (chapter 5).
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The development of high performance concrete with secondary raw materials
Osuská, Lucia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The thesis is focused on the possibility of using secondary energy resources as an additive to concrete to improve some of its resulting properties. The theoretical part is devoted to the problems of shrinkage and prominence hydration process during hydration of the concrete. This section also contains the results of research work from domestic and foreign sources of high temperature fly ash and fluidized bed combustion fly ash use and their using in concrete. The practical part verifies the possibility of using these materials and their combination as an additive to concrete with impact on the physical and mechanical properties.
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Vacuum evaporation efficiency improvement
Havlásek, Martin ; Máša, Vítězslav (referee) ; Vondra, Marek (advisor)
This thesis is focused on experimental work in the domain of vacuum evaporation efficiency improvement. The first part introduces theory of liquids evaporation and its influencing factors, then multi-stage flash distillation technology. The next part of theory is an overview of other technologies used for desalination of sea water and introduction to the design of experiments. In the practical part are selected factors affecting efficiency of device and experiment plan is designed for them. When the experiment is done, optimal operating conditions of technology are designed on basis of analysis.
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High Voltage Switchgear Thermal Distribution Analysis
Bílek, Tomáš ; Rudolf, Pavel (referee) ; Hrabovský, Jozef (advisor)
Cílem této práce je analýza teplotního pole vysokonapěťového rozvaděče. Tato analýza je založena na kombinaci experimentálního měření a CFD simulace proudění vzduchu v prostoru rozvaděče. Na základě výsledků pro referenční geometrii jsou předloženy návrhy na úpravu topologie rozvaděče, které mají za cíl snížení teploty kritických komponent rozvaděče během jeho provozu. Druhá část práce je spojena s problematikou oteplení plošných spojů, jakožto hlavních zdrojů tepla v prostoru rozvaděče. Pro popis závislosti oteplení plošného spoje na jeho charakteru byla použita statistická metoda design experimentu. Výsledky z experimentálního měření jsou podpořeny konečně prvkovým modelem kontaktu spoje.
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