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Determination of evapotranspiration from small catchments
Toušková, Jitka ; Šípek, Václav (advisor) ; Možný, Martin (referee) ; Brom, Jakub (referee)
Evapotranspiration (ET) plays a significant role in the hydrological balance. The terms potential (PET) and reference (RET) evapotranspiration are often used while estimating its rate. The doctoral thesis deals with the estimation of PET, RET and other selected processes. First, the influence of net longwave radiation (the component of radiation balance) on the rate of PET was examined. It was found that the standard methods result in the significant differences in PET estimation due to the absence of model calibration to local conditions. The original model caused distinction in the PET evaluation for the Liz experimental catchment by up to 100 mm/year. Calibration of the parameters of two commonly used methods for calculating net longwave radiation reduced the error in PET evaluation to less than 20 mm/year. PET or RET estimation itself can be performed by many direct or indirect methods. Their accuracy is highly discussed. This work focused on selection of suitable methods and their further testing on conditions of 18 stations in the Czech Republic. 37 methods were compared with measured data. It was proven, that the best results in this region were achieved by combination methods (with average RMSE of 1.2 mm/day, 18.6 mm/month, and 33.3 mm/year). Among individual models, the radiation-based...
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Possibility of using EMW radiation for killing biotic pests
Gintar, Jan ; Klečka,, Tomáš (referee) ; Pěnčík, Jan (referee) ; Šuhajda, Karel (advisor)
The remediation of building elements and structures in terms of moisture and sterilization (inactivation) of biotic pests is dealt with quite often in construction practice and in the construction industry itself, and is thus a topical issue. The issue is dealt with by specialized companies that know the use of available technology on the market, or are themselves involved in the development and improvement of these devices. Several methods are known for the removal of moisture and sterilization of biotic pests, with sufficiently high-quality data on the technology used, the suitability of the equipment used, a more detailed description of the application of the methods themselves and the results themselves. The methods themselves, for removing moisture and eliminating (inactivating) biotic pests, must be chosen according to individual requirements, as some methods will be more appropriate (more effective) and some less suitable. For the practice itself, however, it is important that the methods are sufficiently effective and at the same time available to the wider public (their economic side). In my dissertation thesis I focus on the potential of EMW radiation utilization not only for liquidation of biotic pests (fungi, fungi, wood decaying insects), but also elimination or reduction of necessary conditions for survival or development of these biotic pests. Therefore, my work also focuses on the presence of moisture, because moisture is a common factor in the vast majority of problems associated with the occurrence of biotic pests. Due to its intensity, it is one of the less time-consuming method and therefore a more cost-effective (economically) method. The research I conducted at VUT FAST focused on the use of microwave radiation in the control of biotic pests, under conditions that are close to those on real constructions. The use of a microwave method to eliminate biotic pests and at the same time to remove moisture has proved to be advantageous.
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Modification of heat exchanger for steam generation
Pačíska, Tomáš ; Jegla, Zdeněk (referee) ; Nekvasil, Richard (advisor)
This graduation thesis is concerned with a thermal exchange unit issue whereof one working substance complies with a two-phase mode of a flow. This unit is made for the steam generation. The thesis is supposed to solve operation problems causes of the given unit and to make a proposal of an appropriate solution that is supported by performed calculations. Part of the the work is strength calculation. This work also introduces the thermal-hydraulic processes issue of the steam generation equipment. There are also performed thermal-hydraulic control calculations in consideration of newly set-up operation parameters of the given equipment‘s working substances.
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Fluid Simulation Using GPU
Frank, Igor ; Chlubna, Tomáš (referee) ; Milet, Tomáš (advisor)
This thesis focuses on fluid simulation, particularly on coupling between particle based simulation and grid based simulation and thus modeling evaporation. Mentioned coupling is based on the article Evaporation and Condensation of SPH-based Fluids of authors Hendrik Hochstetter a Andreas Kolb. The goal of this thesis is not purely implementing ideas of the mentioned article, but also study of different methods used for fluid simulation.
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Disposal of Biotic Pests by EMW Radiation
Sobotka, Jindřich ; Klečka,, Tomáš (referee) ; Myslín, Jiří (referee) ; Tomíček,, Oldřich (referee) ; Šuhajda, Karel (advisor)
The possibility of using high-frequency electromagnetic radiation in the construction sector is a common knowledge. Various experiments have been carried out to dry construction materials, or even to destroy biotic pests. However, the majority of these experiments have been executed in laboratory conditions. It means they have been carried out under exact limiting conditions, often very far off those conditions in real building practice. Therefore, this dissertation aims at exploring the possibility of utilizing microwave technology in drying and heating of construction materials, in disposing of biotic pests and sterilizing building materials under real conditions in building practice. The thesis will explain that microwaves are a term given to a part of electromagnetic radiation. Electromagnetic radiation is based on the principle that the radiated energy is absorbed by water molecules present in moist building material. In the mass of the irradiated material, the radiated energy is transformed into thermal energy, where a so-called “motion” of water molecules occurs with the energy then being transformed into kinetic energy. The microwave technology itself offers a very wide range of use, which can be easily achieved, thus making the technology available to use in the future. Part of the experiments and the necessary measurements, too, has been carried out on selected types of building materials in the premises of the Faculty of Civil Engineering of Brno University of Technology. They have been executed under conditions which most closely correspond to the conditions in real buildings. Part of the experiments and the necessary measurements were carried out on particular constructions, by the so-called in situ method. As stated in the conclusion of the dissertation, laboratory measurements and the in situ measurements differ considerably in some cases.
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Integration of a technology for digestate thickening in a biogas plant
Miklas, Václav ; Touš, Michal (referee) ; Vondra, Marek (advisor)
This diploma thesis is mainly focused on the digestate thickening in a biogas plant. First, overview of the biogas technology in the Czech Republic is presented. Furthermore, problems with waste heat utilization and processing of fermentation residues (digestate) are described in more detail. Based on the research, multi-stage flash (MSF) evaporation was chosen as the technology for the digestate thickening. The main part deals with the integration of the chosen technology into a biogas plant process. The programming language Python was used to simplify the given task. In the preliminary stage, a complex mathematical model of a biogas plant was created, focusing particularly on the mass and energy balances. Subsequently, a computational model of the MSF evaporator was programmed. A procedure for the integration was suggested using the sensitivity analyses. Additionally, the model of a biogas plant was extended with the MSF evaporator. The key outcome of the thesis is a technical-economic analysis in which the impact of digestate transport price and electricity feed-in tariff on payback period is investigated. The results suggest profitability of MSF evaporator for biogas plants without subsidized feed-in tariff. Contrastingly, installation of MSF evaporator in older biogas plants with subsidized feed-in tariff can be economically viable only in cases of significantly longer transport distances.
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Study of the influence of nanoparticles on water properties
Šram, Matěj ; Komendová, Renata (referee) ; Řezáčová, Veronika (advisor)
This work deals with the study of the influence of platinum nanoparticles with a size of 3 nm on the properties of water in a porous system. SiO2 with a defined pore size was used as a porous system, which can simulate the mineral component of the soil. The theoretical part deals with the properties of free and porous water and the impact of nanoparticles on the environment. In the experimental part, the properties of free water, water in the porous system and the influence of the presence of platinum nanoparticles on these systems are investigated using differential scanning calorimetry (DSC). The observed processes were melting, solidification and evaporation, and derived quantities such as crystallization and melting point.
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Fermentation remainder treatment in a biogas plant
Budín, Oto ; Touš, Michal (referee) ; Vondra, Marek (advisor)
This diploma thesis deals with dewatering technologies of fermentation residues from biogas plants and aims to design an integration of selected technology into the biogas plant. Fermentation residues (or digestate), which are a by-product of anaerobic biomass fermentation in biogas plants, contain a certain amount of nutrients and are usually used as agricultural fertilizers. However, the high-water content in digestate and the associated low nutrient concentration increase the cost of its storage and transport. Dewatering of fermented material could help reduce these costs. The main part of this work included the design of an integration of the selected dewatering technology into the biogas plant – its placement in a process, an addition of necessary appliances, the influence on material and energy flows. In this case, the fermentation residues are processed in two phases. First, a separation of the solid and the liquid fraction by a screw press. The second step is to thicken the liquid digestate by evaporation in a multistage evaporator. Evaluation of the design of a dewatering technology, including its impact on the economy of the biogas plant, is also part of the diploma thesis.
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Optimization of air conditioning of the wellness sports center
Prchalová, Nikol ; Rubina, Aleš (referee) ; Blasinski, Petr (advisor)
The diploma thesis deals with microclimate of a pool hall. This is divided into three parts. The first part describes the theoretical aspects of the environment in swimming pools in general. The second part of the diploma thesis deals with the calculation of the course of specific moisture concentration during the day in the pool hall. Different humidity concentration curves are assessed based on different electable input parameters. Subsequently, suitable setting options are evaluated in order to achieve acceptable environment in the hall in terms of humidity and optimal operating costs. The last part relates to the experimental part. This examines the measurement of evaporation under different boundary conditions and the subsequent comparison with some calculation methods for the calculation of evaporation.
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