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Analysis of Flow Distribution in Systems with Dense Tube Bundles
Babička Fialová, Dominika ; Dohnal, Miloslav (referee) ; Turek, Vojtěch (advisor)
Considering heat transfer equipment with dense tube bundles, it is essential to ensure as uniform a fluid distribution into the tubes as possible in order to prevent various operating problems. This bachelor’s thesis therefore focuses on tube-side flow analysis in such equipment. CFD simulations were carried out using a diverse set of flow systems with outflow into a constant-pressure environment. The respective tube bundle geometries differed in densities and sizes, arrangements of the tubes, and tube diameters. Air was used as the working fluid in the majority of the cases, however, some of the simulations were also carried out with water. Data obtained from evaluations in the fluid flow modelling software ANSYS Fluent were further analysed and the influence of the mentioned differentiating parameters on flow distribution non-uniformity and pressure drop was investigated. According to the regression model, the dependence of flow distribution non-uniformity on density and size of the bundle and on mass flow rate per unit outflow area cannot be rejected with the standard significance level. As for pressure drop, the only parameter that was not rejected was mass flow rate per unit outflow area.
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Evaluating and modeling of fouling process in heat exchanger
Čirka, Martin ; Kilkovský, Bohuslav (referee) ; Jegla, Zdeněk (advisor)
This diploma thesis discusses fouling processes and mechanisms of industrial heat exchangers, with focus on shell side fouling of heat transfer area by flue gases, and eventually taking fouling into account, or more precisely its modeling and predicting by calculation. Thermal-hydraulic design of heat exchanger is focused mainly on shell side, as flue gases are dominant process medium in terms of fouling and heat transfer. Based on available operational data of evaluated industrial heat exchanger, specific process has been developed to determine by calculation, or more precisely predict change of fouling factor throughout operational period of heat exchanger. Usage and various options of this specific calculation technique are being discussed in conclusion, whether there is a potential to use this technique regarding more complex operational inputs or prediction of fouling process for different operational regime of heat exchanger.
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Heat recovery from melting furnace waste gases
Dobai, Szabolcs ; Hejčík, Jiří (referee) ; Jaroš, Michal (advisor)
This master’s thesis deals with the design of heat recovery system from melting furnace waste gases. The first part is devoted to a brief description of heat exchangers, with the special importance being placed on the shell-and-tube heat exchanger. The second part contains a calculation of stoichiometric combustion, design of geometrical dimensions, calculation of pressure drops and power. At the end of the thesis there are various possibilities of utilization of the obtained waste heat and their basic economic assessment.
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Experimental support for the development of specific integrated equipment
Hrbáček, Jiří ; Jegla, Zdeněk (referee) ; Kilkovský, Bohuslav (advisor)
Regenerative heat exchangers are used in a wide range of industries and in the technical equipment of buildings. These heat exchangers play an important role in saving thermal energy and removing volatile organic compounds from flue gases. The theoretical part of the work deals with the division of regenerative exchangers into rotary and switching exchangers and the possibilities of their use. These types of heat exchangers are used in many applications, e.g. as a heat exchanger using waste heat to preheat the process gas (regeneration layer), or as catalysts to accelerate the reaction required to remove volatile organic compounds (catalytic layer), or as integrated equipment where both the regeneration layer and the catalytic layer. The aim of the diploma thesis is experimental support in the development of a computer program for the design of a specific integrated device. The program allows the calculation of the regeneration and catalytic bed, or both beds simultaneously, i.e. integrated equipment. The diploma thesis deals with the support of a mathematical model for the calculation of the regeneration bed. Pressure loss and heat transfer play an important role in the selection and subsequent calculation of a suitable bed. To calculate them, it is possible to find more available computational relationships that differ significantly in their accuracy. It is therefore necessary to select the most suitable ones for the computational model. The practical part of the work then deals with research, analysis, and assessment of the suitability of methods used to calculate pressure losses based on a comparison with the values measured on experimental equipment. Subsequently, the work deals with computational methods for determining the heat transfer coefficient of the packed bed. A significant part of the practical part deals with the modification of the experimental equipment for the verification of computational relations for the determination of heat transfer with measured data.
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Absorption Cleaning of Flue Gases Arising from the Incineration of Wastes
Jecha, David ; Klemeš,, Jiří (referee) ; Žaloudík, Petr (referee) ; Bébar, Ladislav (advisor)
This doctoral thesis deals with potentials of methods for cleaning of flue gas from pollutants such as acidic components. Wet method of flue gas cleaning is analysed in detail with special focus on elimination of sulphur dioxide (SO2). Introduction presents advantages and disadvantages of thermal processing of waste and production of undesired pollutants. Following parts comprise facts about main pollutants produced from incineration. Legislation providing for emission of gaseous pollutants from incinerators is also given. Chapter concerning methods of pollutants elimination is mostly focused on absorption (wet and/or semidry scrubber) and adsorption methods. Several up-to-date technological procedures are mentioned; they have a multifunctional effect such as elimination of acidic components, heavy metals, polychlorinated dibenzo-p-dioxines and dibenzo-furanes from flue gas using single injection of suspense. Elimination of mercury (Hg) is among the technologies for heavy metal elimination which is described in detail. Main part of the thesis is related to experiments at two-stage flue gas cleaning equipment. Function of this experimental unit is described along with methods for measurement of individual quantities and detailed description of all the equipment and its components. Experimental measurements carried out at this equipment are explicated and assessed. Along with experimental work, the author has created a simulation model of wet flue gas cleaning in ChemCad programme. Particular operational parameters were tested on this model. This thesis contains results of the measurement which provide background for verification of the mathematical model. Further, the balance of heavy metals conducted on the basis of measurements in waste incinerator is displayed. Main contribution of the thesis may be summed up as follows: Author has designed and constructed experimental equipment for two stage flue gas cleaning. He also formed calculation for pressure drop of O-element prototype equipment and for packing column with FLEXIPAC structured packing. He created data file with measurements at the experimental unit. He determined temperature at outlet of a random device where liquid is injected into stream of hot flue gas. He designed a simulation model which is identical with experimental equipment and which usage enabled comparison of measured and calculated data; it also serves as a basis for industrial applications. Last part deals with creation off heavy metals balance in a case industrial waste incinerator.
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Heat transfer design
Murín, Milan ; Brázdil, Marian (referee) ; Špiláček, Michal (advisor)
The bachelor thesis deals with a design of water – water heat exchanger with two types of baffle systems, disk and doughnut, and segmental. The thesis contains classification and description of tubular heat exchangers, geometry design, and calculation of pressure drops and heat transfer of the device for both eventualities. It also contains construction drawings of both types of baffles.
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Air filtration
Krajčová, Kateřina ; Uher, Pavel (referee) ; Rubinová, Olga (advisor)
The diploma thesis describes the design of air conditioning equipment of materni-ty hospital and experimental measurement nanofilters and their subsequent comparison with conventional air filters. The work consists of three parts. The first part describes the types of filters. Nanofilters and nanofiber materials are de-scribed in detail here. In the second part is the topic of air filtration applied to the maternity hospital. Two variants of air conditioning and cooling are designed for the 3rd floor of this building. The third experimental part deals with antibacterial effects of thr silver fiber nanofilter and its comparison with commonly used filters. It also deals with the pressure drop on the filters at different air speeds.
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Calculation of pressure losses of flue gas ducts using mathematical modeling
Suchý, Václav ; Skála, Zdeněk (referee) ; Pospíšil, Jiří (advisor)
This diploma thesis deals with the calculation of pressure losses in the flue gas ducts. First part of this work describes properties of flue gas and flow dynamics. Part of the theoretical analysis was detailed study of pipeline elements with emphasis on the reasons for the existence of pressure loss in the flow, calculations of the resistance coefficients and possible methods of reducing the losses. In the practical part, a model of the pressure loss calculation of the existing flue gas line installed in the incineration plant was created. At the end of the thesis a proposal for optimization of this route was made with emphasis on the reduction of the overall pressure loss. By optimization the pressure drop of the specified route was reduced from 3581 Pa to 2647 Pa, i.e by 26% and the required power input of the fan was reduced from 225 kW to 166,5 kW.
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CFD geometry optimalisation of heat exchanger
Stromský, Ondřej ; Gottvald, Jakub (referee) ; Nekvasil, Richard (advisor)
The main task of thesis is to find optimum geometry of the heat exchanger. The biggest emphases is placed to finding the most optimum of streaming liquid in the heat exchanger and to minimisation pressure losses. There is a effort to regulate the streaming liquids in heat exchangers so that in multitube and on the shell side don´t create dead areas, it means to avoid sedimentation of particle in these places. Dead areas cause rising resistance against heat transfer and necessity of frequently cleaning the heat exchanger. For these reasons is necessary to do analyse of flowing and to looking for the optimal geometry of the heat exchanger.
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