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Plastic plating
Čermák, Jan ; Kubíček, Jaroslav (referee) ; Žák, Ladislav (advisor)
The perspective of the production of plastic parts has helped to spread the metallization of these parts on a large scale. Whether a coating is functional or just decorative. This bachelor thesis presents a comprehensive study, analysis, evaluation and comparison of the possibilities of creating metal coatings on plastic materials. The thesis deals with galvanic, chemical, vacuum and special methods of plating. For all the mentioned methods of plating, the technological procedure, equipment for plating, evaluation of individual methods and analysis of the use of plated plastic parts are given.
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Impact assessment of the use of hydrogen-enriched natural gas
Galík, Tomáš ; Pospíšil, Jiří (referee) ; Baláš, Marek (advisor)
The Master’s thesis reviews the topic of hydrogen in within European and Czech energy industry. Hydrogen’s usage in gas industry, heating industry and power engineering may play a significant role in meeting European Union’s ambitious goals aiming to reduce emission production. This work identifies specifications of technologies used to produce, transport, and use of hydrogen and their impact on today’s energy systems and safety. The technical, economic, and political context is emphasized. The technical part covers the topic of injecting hydrogen into natural gas and it’s impact on physico-chemical properties of gas. The work analyses concentrations of 0, 5, 10, 15, 20 and 25 molar percent of hydrogen in real composition of natural gas measured on a handover point of transition system. Furthermore, calculations for these mixtures have been done to determine a change in characteristics of a heat exchanger. The results show, that with higher concentrations of hydrogen, the power of heat exchanger rises, while the power of a burner decreases due to lower calorific value of gas mixture. The last chapter follows up on a economical analysis of fuel and emission allowance costs for above-mentioned concentrations of hydrogen in gas mixture. Specific values of combined cycle gas plant Počerady from year 2019 were used for calculations. The results show, that in all of the three considered scenarios of emission allowance price predictions, replacing hydrogen with natural gas did not have a positive economic impact.
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Study of properties of electrolytically modified NaCl solutions.
Brázda, Lukáš ; Mika, Otakar Jiří (referee) ; Mašek, Ivan (advisor)
This work concentrates on the study of properties of NaCl solutions, prepared by electrolysis and their using for disinfection of water. Then it is focused on reporting on possibality for corrosin of metals, whice are used in water distribution. For study was used 0,25 mol/l, 0,1 mol/l, 0,05 mol/l NaCl solutions and input direct-current voltage for electrolysis was 6V a 12 V. During the electrolysis pH and conducitivity were measured. After the end of electrolysis free active chlorine and chlorides were determined on the time. For electrolysis was used diaphragm.
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Hydrogen production from renewable sources
Balko, Michal ; Kropáč, Jiří (referee) ; Houdková, Lucie (advisor)
The goal of this bachelor's thesis is to make a summary of actual hydrogen production possibilities both from fossil fuels and from renewable sources. First part deals with production by steam reforming of natural gas and water electrolysis. Next comes the production from biomass by photofermentation and fermentation. Attention is paid especially to input materials and process conditions. In the end chosen processes of production are compared by their energy intensity found out by simplified calculation.
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Electric characteristics of the diaphragm discharge in electrolyte solutions
Dřímalková, Lucie ; Slavíček, Pavel (referee) ; Kozáková, Zdenka (advisor)
The main object of this thesis is the diagnostics of the diaphragm discharge generated in water solutions containing supporting electrolytes (mostly NaCl), and description of particular processes before and after discharge breakdown by DC non-pulsed voltage up to 2 kV. Although many applications of electric discharge in liquids have been developed during the last years, the exact mechanism of the discharge ignition is not sufficiently known up to now. Based on this reason, this work is focused on the investigation of processes before the discharge ignition, breakdown parameters and the discharge itself both in the irregular and stable regime. The theoretical part of the work presents proposed mechanisms of the discharge generation in water solutions including the description of particular kinds of known discharges. Diaphragm discharge is one of many possible configurations of electrical discharges in liquids. In fact, electrical discharge in water forms non-thermal plasma, which is generated by high voltage, and many physical and chemical processes are started in plasma channels (so-called streamers). Among physical processes, high electrical field, shock waves and last but not least emission of electromagnetic radiation in visible and ultra-violet radiation belongs. The most important chemical processes are generation of various active species as hydrogen peroxide, and OH radical. Three batch plasma reactors using a diaphragm configuration with different total volume (4 l, 100 ml and 50 ml) are employed in the presented work. The discharge is created in an orifice (a pin-hole) in the dielectric barrier separating two electrode parts of the reactor. DC non-pulsed high voltage up to 4 kV is used for the discharge generation. Electrodes are made of stainless steel or platinum, and they are installed in parallel to the diaphragm in a variable distance from the dielectric barrier in each reactor part. The dielectric barrier is made of PET or Shapal-MTM ceramics with the variable thickness (0.2?2 mm). One pin hole st the diaphragm center with diameter of 0.2?1.5 mm are used in contemporary experiments. Time resolved characteristics of current and voltage are recorded using four-channel oscilloscope which detected their output values. Parameters are measured by the constantly increasing DC voltage with a step of 100 V. The solutions containing sodium chloride electrolyte are used at five different conductivities. Recorded time resolved characteristics determine breakdown moment, and describe current and voltage in particular parts within the static current-voltage curve. The breakdown appeared at lower applied voltage when the electrode distance is enhanced. However, the electrode distances higher than 4 cm does not induce any significant change of the breakdown voltage. The influence of pin-hole diameter is less obvious in the studied range, but a slight enhancement of breakdown voltage is observed with the increasing pin-hole diameter. Current-voltage characteristic curve moves towards lower voltage with the diaphragm thickness enhancement. The work compares the influence of conductivity change on current-voltage characteristics as well as the effect of inorganic salt kind. By the conductivity enhancement, the measured current-voltage curve moves towards lower voltage which means that the breakdown voltage is decreased. Sizes of the reactors do not have any effect on the processes before and after discharge breakdown.
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Deposited layers based on lead and cobalt for Li-ion batteries
Dorotík, David ; Libich, Jiří (referee) ; Máca, Josef (advisor)
The diploma thesis deals with the principles of operation of lithium ion batteries and their properties when using deposited thin films. The thesis is mainly focused on the formation of thin films using the electrolytic method and subsequently testing the properties of the thin film in an electrochemical cell. The test criteria are mainly the value of the capacity of the prepared electrode and the impact of cycling on the electrode layer itself, where the deposited layer is assessed before cycling and after cycling on an SEM microscope..
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Influence of electrolysis on the degradation of dye water solutions
Olexová, Barbora ; Možíšková, Petra (referee) ; Kozáková, Zdenka (advisor)
The basic subject of this thesis is to investigate the influence of electrolysis on degradation of organic dyes in aqueous solutions. Electrolysis is a physically-chemical process, during which - under the influence of direct current - chemical reactions proceed inside the system. By choosing efficient conditions it is possible to achieve fundamental changes in the structure of organic compound’s molecules and on the basis of that for example their gradual degradation. This effect can be used in the process of wastewater treatment. The main task of the thesis is to analyse the influence of variously chosen chemical and physical conditions on the rate of degradation of azo dyes, which is the largest group of organic dyes used in industry and from this reason in great amounts contained both in mill residues and sewage water. Azo dyes have been selected for this experiment for their good solubility in water. Other advantage is that their degradation is accompanied by visible decoloration of the solution and their concentration in solution can be easily determined by UV-VIS spectrometry. Concretely two direct azo dyes - C.I. Direct Blue 106 and C.I. Direct Red 79 - have been chosen. The experiment was carried out in a simple reactor consisted of a bath with a stirrer into which two electrodes were installed and attached to the source of direct voltage. Every series of measurement proceeded at constant current which values were varied in range from 100 mA to 1 000 mA. The electric voltage ranged from 7 V to 22 V. Several samples were taken away from the solution during the experiment and the decrease of dye concentration was evaluated in every series. This evaluation validated the hypothesis that the dyes contained in the solution really degraded. This process was also connected to the expected bleaching of the solution. Decoloration of aqueous solution of dye is caused by disruptions in the structure of the dye molecule which is loosing its characteristic sections that cause colourfulness (a conjugate system of double bonds and presence of appropriate substitutes). A total amount of measured series was 16 with various input conditions (Fe and Pt electrodes, electrolytes NaCl, Na2SO4, and NaNO3 and their different concentrations, different current values) which more or less influenced the rate of degradation of investigated substances. It was found out that the blue dye is more likely to be electrolytically degraded. Chemical structure of its molecules, which is smaller and less branched than molecules of the used red dye, could be the source of that. The greatest degradation of the blue one proceeded at two chosen maximum values of constant current 800 mA and 1 000 mA. It could be assumed that current enhancement through the system induces higher dye concentration decrease. Degradation of the blue dye proceeded faster by using electrodes made of stainless steel than the platinum electrodes. The most suitable electrolyte was shown to be sodium chloride. When higher concentration (or conductivity) of electrolyte was used higher efficiency of degradation process was observed.
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Seasonal accumulations using power-to-gas technology
Zavadil, Jan ; Martin Pešek (EGÚ Brno, a. s. ) (referee) ; Pospíšil, Jiří (advisor)
The diploma thesis is focusing on the seasonal energy storage in synthetic fuels and the Power to Gas system (P2G). The P2G enables the conversion of electrical energy in times of electricity surplus, for example by using the surplus from renewable energy sources to produce synthetic gas, particulary hydrogen and synthetic methane. The main focus is on the technical and economic assessment of P2G of the Gazela natural gas pipeline. Furthermore, it identifies the limits of production, transportation, and storage capacities of these synthetic gases. The technical analysis assumes the injection of hydrogen of a certain molar concentration, according to the four proposed scenarios, into the natural gas transmission system in the Gazela pipeline. The results have showen that an increase in the molar fraction of hydrogen in natural gas will cause problems in gas transport and will lead to an increase in the pressure losses, an increase in flow rate, and a decrease in the storage capacity of the pipeline. The economic analysis examines the use of P2G technology in Czech conditions. It demonstrates the amount of production costs for the production of 1 MWh of synthetic gas depending on the electricity price and the operating time of the production facility. The sensitivity analysis has shown that neither hydrogen nor synthetic methane is competitive next to cheap natural gas unless measures like an increased price of emission allowances or a carbon tax are taken.
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Hydrogen fuels
Umlauf, Martin ; Bébar, Ladislav (referee) ; Jícha, Jaroslav (advisor)
Paper presents a basic review and comparison of energy-conservation made of renewable sources. Principal question of paper concerns evaluation of hydrogen-use made of electrolysis of water. First part of the thesis focuses on the production of energy from renewable sources and the possibility of energy-accumulation. The next section describes methods of hydrogen production and utilization of hydrogen as a fuel for combustion engines. Attention is paid to various aspects dealing with construction of combustion engines using hydrogen. Final part of the study presents comparison between combustion engines using known sorts of fuels as to their pollution and emission-level. Next comparison deals with economic cost per kilometer, when different sort of fuels are taken into account. Conclusion concerns approximate calculation of the production of hydrogen from water by electrolysis using photovoltaic power plants.
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Determination of Hydrogen Mixture Influence on Internal Combustion Engine
Roušar, Jiří ; Dlugoš, Jozef (referee) ; Novotný, Pavel (advisor)
The aim of the Bachelor thesis is comparing a hydrogen combustion engine with conventional combustion engines and comparing the advantages and disadvantages of the hydrogen combustion engine. The features of hydrogen are introduced, as well as its production, transportation and storage. The work contains a research of construction designs of a conventional engine modifications to the hydrogen engine. The realisation of technically possible modifications to the conventional engine is included in the thesis.
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