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Polymeric Hollow Fiber Heat Exchanger Design
Astrouski, Ilya ; Dohnal, Mirko (referee) ; Horák, Aleš (referee) ; Raudenský, Miroslav (advisor)
This Ph.D. thesis is focused on theory and experimental investigations developing of new knowledge about polymeric hollow fiber heat exchanger (PHFHE). The state-of-the-art study of plastic heat exchangers shows that their usage is limited by several niches where their advantages significantly dominates, or where the use of non-plastic competitors is not impossible. On the other hand, plastic heat exchangers (and PHFHEs in particular) are devices of increasing interest. It is shown that use of small tubes (fibers) allows PHFHEs to be more competitive than conventional plastic heat exchangers. Small hydraulic diameter of a fiber causes high heat transfer coefficients, reduces thermal resistance of plastic wall and allows it to create light and compact design. Detailed study of fluid flow and heat transfer inside the hollow fiber showed that conventional approaches for single-phase laminar flow can be utilized. Poiseuille number equal to 64 and Nussel number about 4 are recommended to be used to predict pressure drops and heat transfer coefficient, respectively. Additional attention should be paid to careful determination of fiber diameter and liquid properties (viscosity). Scaling effects, such as axial heat conduction, thermal entrance region and viscous dissipation can be neglected. The study of outside heat transfer showed that heat transfer on fiber bunches are intense and are competitive to contemporary compact finned-tube heat exchangers. The Grimson approach showed clear correlation with experimental results and, thus is recommended to predict heat transfer coefficients on fiber bunches. Two types of fouling (particulate- and biofouling) of outer fiber surface were experimentally studied. It was found that particulate fouling by titanium oxide particles is not intense and deposits can be removed relatively easy. However, fouling is much more intense when it is associated with biofouling caused by wastewater. In this case, smooth and low-adhesive surface of plastic is not sufficient precaution to prevent deposit formation.
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Theoretical use of nanotechnology for filtration in HVAC systems
Bosák, Jan ; Ell, Jiří (referee) ; Rubina, Aleš (advisor)
Thesis solves problems using the nanotechnology for air filtration in HVAC systems. Main specialization work is air filtration for clean spaces with high classes of purity. For example Hospitals, sophisticated technology service, pharmacy etc. Thesis is devide for three parts. First part contains foundation infromations about theory and making fabrics by nanotechnology. Next I described laws of physics, That were using during the solving filtration´s issues. Goal for second part was making the experiments, which should show abilities and properties nanofilters during the air filtration in real environment HVAC systems. In the end measure part is compare nanofilters with common filters. There is describe nanofiltres behavior and their possibilies during the filtration as well as. In last part I expressed own opinions on air filtration by nanofibers. Opinions were making throught informations, That I found out in the process working on thesis and my experiences in HVAC field. By this facts I did compare for get a better idea. Additionally last part contains summary infomations from previously parts and own vision to development in the future. Goal work isn´t promotion and advertising sorts technologies. Ask is just summary and describe discovered knowledges, considered opinions ensue from measuring, information from the Net and people Who work in nanotechnology field.
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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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Cleaning of biogas by the PSA (pressure swing adsorption)
Navrátil, Petr ; Houdková, Lucie (referee) ; Leštinský, Pavel (advisor)
The topic of this master thesis is upgrading of biogas. As a mixture of gases produced during anaerobic digestion, contains methane which is highly energy valuable gas. But also other substances that we want to remove. We will present the motivation for upgrading biogas and the possibility of separation, generally the pressure swing adsorption method. The key parameter of this technique is the choice of a suitable adsorbent. This is possible based on the knowledge of adsorption processes, therefore, is also described below. The objective of this thesis is to determine the parameters of the pressure swing adsorption metod. To do this it is necessary to determine the adsorption capacity of the adsorbent, measure breakthrough curves of carbon dioxide and methane, and determine the pressure drop of solid bed, etc. As a result we can finally make a balance and evaluate the applicability in practice.
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Evaluation of the alternatives of PCDD/F removing in the incineration plants
Frýba, Lukáš ; Kropáč, Jiří (referee) ; Bébar, Ladislav (advisor)
The thesis is focused on analyzing the current status of the technology used for cleaning flue gas from persistent organic pollutants, especially PCDD/F. For the three most commonly used methods of solution operational and energy efficiency comparison was made, where achievable energy export and the impact of the change in working conditions on the efficiency indicators of energy production and use of the energy was evaluated. In conditions we considered an alternative machine-technological solutions used for the final disposal of persistent organic pollutants resulting from the waste combustion in terms of additional operating costs and energy efficiency.
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Tube heat exchanger for heating water.
Novotný, Roman ; Rostislav, Ratkovský (referee) ; Skála, Zdeněk (advisor)
Target of the master´ thesis is a design of heat exchanger air-water with the air flowing inside the pipes and with staggered pipe configuration, based on the engaged and chosen values. Next target is to determine heat exchanger with cross parallel flow and cross countercurrent flow of mediums, pressure drop on both sides air and water and dimensions of intake and outgoing gate on both sides air and water.
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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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Hydrodynamic analysis of basic equipment in units for the thermal processing of wastes
Říha, Kamil ; Kilkovský, Bohuslav (referee) ; Pařízek, Tomáš (advisor)
Thermal processing of wastes is a metod, when during combustion occur reduction of wastes till 10% previous volume. The main advantage of this method is possibility to heat utilization for heat and electric production. Through thermic process develops range of pollutants (NOx, CO, SO2, HCl, HF, PCDD/F) that had to be remove from off-gas or reduced to enviromental values in agreement with laws in force [16]. For this purpose are combustion units equip with range of devices for removing this pollutans. The main task of this diploma thesis is selectoin of ctirical device in term of pressure drops. The value of pressure drop stands significant part in proposition of efficiecy off-gas fan. In increase or decrease total pressure drop consumption of electrical energy of off-gas fan is rising or going down. Change of consumption in total classification is projecting in energy utilization rate of waste where is determinate if it stands of energy utilizatoin or just incineration. In first part of diploma thesis are described in detail availability methods of off-gas cleaning where is described their principle, advanteges, disadvatages and comparison of effectivity. In second part of diploma thesis is made example model about influnce technology on value of total pressure drop. There were chosen two technologies for removing dioxins (technology of catalytic filtration REMEDIA and DeNox/DeDiox). For both technologies were made detailed analysis of pressure drops single components of these technologies. Attainment results were compared and rated with one another. For analysis these two methods were designed mathematical process in software Maple 9.5.
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Evaluation of the solar system in VUT Fast
Bublan, Tomáš ; Počinková, Marcela (referee) ; Horák, Petr (advisor)
The main purpose of the diploma thesis is the evaluation of the solar system at the BUT FCE and the application of the topic on the specified building. The specified building was the story cellarless kindergarten with flat roof. There were proposed two variants of applications of the solar collectors: the solar heating of warm water or combination of solar heating of warm water with the support of heating.
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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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