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Visualisation of the flow in the ventilation unit
Šebetka, Kryštof ; Fišer, Jan (referee) ; Pech, Ondřej (advisor)
This bachelor thesis deals with the basics of hydrodynamics. The basic principles and functions of flow visualization are described. Different types of visualizations are also discussed, followed by a list of specific visualization methods that are described in more detail. Another topic is ventilation and air conditioning. The thesis includes a short summary of the historical development of ventilation and air-conditioning and brief information about this industry. General descriptions of the components that are most relevant to the industry are also covered. Then the thesis comes to the experimental part, where is description of the ventilation unit inside which the flow visualization was performed. This is followed by the description of the experiment itself, the aim of which was to perform the flow visualization by the smoke method inside the ventilation unit, the construction of which was gradually modified to make the visualization as simple as possible and as recognizable as possible. The apparatus for the visualization is described, as well as the process of gradual development of the unit, how the different components had to be modified to improve the quality of the visualization. This is illustrated in photographs showing the flow before and after the modifications. The last section describes the process of trying to reduce the pressure losses that occurred between the different components of the ventilation unit, which were measured and compared at different stages of the modifications.
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Design of the thermal output for district heating line from the Dukovany nuclear power plant
Houzar, Filip ; Kracík, Petr (referee) ; Milčák, Pavel (advisor)
The topic of this master's thesis is the analysis and comparison of possible designs of thermal power output from the nuclear power plant Dukovany to meet the needs of the city of Brno. The beginning part of this thesis contains research on the current state of the heating industry in Brno, including current industrial heating sources and heat consumption. This research also includes a summary of the secondary circuit of the Dukovany NPP, from which the heat will be obtained. Three possible designs of heat output will be proposed in the next chapters, varying in the use of steam extracted from the steam turbine and the placement of heat exchangers. The last part of this thesis contains the basic design of a district heating pipeline necessary for the long-range transport of heat from Dukovany to Brno.
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Reuse of wastewater in multifunctional buldings
Skřička, Jakub ; Úterský, Michal (referee) ; Hlavínek, Petr (advisor)
This diploma thesis presents reader with current knowledge in the field of gray wastewater reuse. The theoretical part describes the current state of water in the world, thus characterizes wastewater and describes its treatment. Further, this section describes the possibility of obtaining thermal energy from wastewater. At the end of the theoretical part, the reader is presented with some existing buildings in the Czech Republic that use the wastewater re-use technology system. In the following practical part, all the knowledge from the theoretical part are applied for a concrete project of construction of a graywater re-use technology system in the area of Vlněna in Brno city.
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Quantification of measurement accuracy of the pressure losses at evaluation of aluminium casting porosity
Velehradský, Petr ; Jelínek, Milan (referee) ; Pernikář, Jiří (advisor)
The diploma thesis deals with a matter of a leak testingo of the Schreiner devices in the company Kovolis Hedvikov a.s. The tested components are the heat exchangers made from alloy of aluminium used for automobiles. Due to the impact of porosity texture created during the components casting there is leaking. The analysis was accomplished to find out the most problematic parts of these components. Subsequently the testing and measuring were performed in order to classify the testing and detect its accuracy. The summary and suggested solutions of how to improve the accuracy of measuring of the aluminium components leaking are presented in the conclusion.
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Technology solution for energy savings in industrial processes
Cyž, Antonín ; Miklas, Václav (referee) ; Konečná, Eva (advisor)
This bachelor thesis is a search of known technological solutions for energy saving in industrial processes. The first part contains a description of the methodology for the analysis of energy consumption in the company. The first part also solves some of the statutory obligations of an energetic area in companies. Then follows a description and possible use of individual technological devices. The theoretical part of the work evaluates and describes the possibilities to increase the energy efficiency of an industrial laundry. Finally, the economic – energy balance of a specific operation is analyzed, including the evaluation of the financial return on investment.
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The efficiency of heat exchangers in the cryogenic processes
Horvát, Petr ; Krištof, Ondřej (referee) ; Svěrák, Tomáš (advisor)
Heat exchangers and their use in cooling processes are the major topic of this thesis. The theoretical part of the thesis deals with the mechanisms of heat transfer, outlining their problems at low temperature. Furthermore, the thesis describes the types of heat exchangers used in practice, then a relatively large part dealing with the problem of calculations connected with tube heat exchangers is included. Relations for both normal and cryogenic conditions are given. In the experimental part, the heat transfer on the semi-operating glass tube heat exchanger is examined by cooling the room air with 55% ethylene glycol in order to compare the heat-transfer coefficients determined from the heat balances and from the dimensionless criteria based on the relations mentioned in the theoretical part of the thesis. For a pair of coolant flows and four airflows, input and output flow temperatures, pressure and relative air humidity at the inlet were measured. At higher airflows, more than double efficiency of heat exchange was observed, at the lowest airflow the exchanged heat was up to half against the theoretical model. The reason for these deviations is probably the condensation of air humidity in the heat exchanger and the design of the heat exchanger. The flow of coolant had practically no influence on the amount of heat exchanged. As found, for the studied heat exchanger it is non-effective to operate in low airflow modes and it is unnecessary to operate at higher flow rates of the cooling medium.
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Heat transfer surfaces design and fouling of the heat exchangers from hollow plastic fibers
Bokišová, Lenka ; Dohnal, Mirko (referee) ; Raudenský, Miroslav (advisor)
This thesis studies a possibility of using hollow fibres for construction of innovative heat exchangers. The first part introduces to the field of heat exchangers and polymers as materials suitable for formation of heat transfer surfaces. Further, the potential of hollow fibres of small diameters is outlined, including the merits, limits and proposals for improving. The significant part of the work is dedicated to the review of methods of fibres fixation and separation and review of fouling and cleaning of heat exchangers. Overviews of design possibilities which prevent fibres clustering have been made. The solutions, which are prepared for experimental research at Heat Transfer and Fluid Flow Laboratory are stated, including analysis of “curly” fibres application. The next part presents calculations for models of water – water and water – air heat exchangers and discusses influence of fibre diameter, flow velocity and the other parameters on heat characteristics. The heat transfer and fluid flow formulas using for heat exchangers of a bigger order can be employed with small changes. Furthermore, the influence of hollow fibres arrangement and distances on heat transfer is discussed.
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Sewer mining
Šebek, Josef ; Macsek, Tomáš (referee) ; Hlavínek, Petr (advisor)
This bachelor thesis presents the topic of waste water reuse straight from the sewer system (sewer mining). It contains energy recovery (heat recovery in particular) from sewer system as well as wastewater treatment and reuse in demanded locations, in compliance with the policies of circular economy. The first part contains research of wastewater topic. Individual components of municipal wastewater, treatment and reuse options are characterized in this part of thesis followed by more detailed description of methods and technologies for heat recuperation from wastewater; and available technologies for sewer mining options at the end of the first part. The second part contains a technical study about wastewater heat recovery on a specific location.
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Modelling of flows in a heat exchanger
Hudeček, František ; Milčák, Pavel (referee) ; Špiláček, Michal (advisor)
This thesis considers problematics of calculating and designing heat exchangers. First way of solving the designing problem is by using mathematical formulas for heat transfer, which are based on manifold measurements. Second approach is can be considered modern as the designing of heat exchangers is realized by using computing technology and appropriate software for simulation of flow and heat transfer. These computations are realized for specified type of heat exchanger that is chosen after a brief research. The results are then post processed, commented and these two approaches are compared and evaluated.
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Flow Induced Vibration Fatigue Analysis of Tube Bundle
Buzík, Jiří ; Vincour, Dušan (referee) ; Lukavský, Jiří (referee) ; Vejvoda, Stanislav (advisor)
The aim of the dissertation thesis is the control of the tube bundle on the cyclic fatigue caused by the flow past tube bundle. Fatigue due to flow is caused by flow-induced vibrations. Examined vibrations are caused by the mutual interaction of two phases (solid and liquid). The present work is focused mainly on the interaction of tube bundles with fluid. The current level of knowledge in this field allows to predict mainly static respectively quazi-static loading. These predictions are based on methods of comparing key vibration variables such as frequencies, amplitudes or speeds (see TEMA [1]). In this way, it is possible to determine quickly and relatively precisely the occurrence of a vibrational phenomenon, but it is not possible to quantitatively assess the effect of these vibrations on the damage of to the tube beam and to predict its lifespan, which would require the determination of the temperature field and the distribution of forces from the fluid on the beam. The aim of the work is to evaluate the-state-of-the-art, to perform a numerical simulation of the flow of fluids in the area of shell side under the inlet nozzle. Current methods of numerical analyses very well solve this problem, but at the expense of computing time, devices and expensive licences. The benefit of this work is the use of user-defined function (UDF) as a method for simulating interaction with fluid and structure in ANSYS Fluent software. This work places great emphasis on using the current state of knowledge for verifying and validation. Verifying and validation of results include, for example, experimentally measured Reynolds and Strouhal numbers, the drag coefficients and for example magnitude of pressure coefficient around the tube. At the same time, it uses the finite element method as a tool for the stress-strain calculation of a key part on tube such as a pipe-tube joint. Another benefit of this work is the extension of the graphical design of heat exchanger according to Poddar and Polley by vibration damages control according to the method described in TEMA [1]. In this section, the author points out the enormous influence of flow velocity on both the tube side and the shell side for design of the heat exchanger to ensure faultless operation. As an etalon of damage, the author chose a heat exchanger designated 104 from the Heat Exchanger Tube Vibration Data Bank [3]. With this heat exchanger, vibrational damage has been proven to be due to cutting of the tubes over the baffles. The last part outlines the possibilities and limits of further work.
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