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Academic literature on the topic 'Dvoufázový součinitel přestupu tepla'
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Dissertations / Theses on the topic "Dvoufázový součinitel přestupu tepla"
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Loibl, Jan. "Výrobník ledu s přímým odparem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231819.
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The theoretical part of the diploma thesis deals with introduction to the issue of refrigeration systems with thermal energy storage. Possibilities of thermal energy storage with phase change are introduced. The thermodynamic principle of functioning of the particular refrigeration system type is explained here as well as its coefficient of performance and fundamental components. In addition, several examples of ice-making systems are discussed. In the practical part the design of a particular refrigeration system is calculated. The main part of the design is the cold evaporator with direct evaporation and the possibility of ice production and its usage for thermal energy storage. The calculation of the overall two-phase heat transfer is carried out.
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Belko, Milan. "Součinitele přestupu tepla na parou obtékaných plochách parních turbín." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230763.
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This thesis in introductory part aims to analyze the available literature on the heat transfer coefficient in labyrinth seals and rotating discs of steam turbines. The available experiment studies were processed to summarize heat transfer coefficients on the rotating parts of the turbine. Then, this thesis specifies a design calculation to determine the heat transfer coefficient in selected parts of the turbine, exercisable for specific geometric and operating parameters. The outcome of this work is simulation of rotor dilation of operating steam turbine in the program Ansys during cold start of turbine.
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Fiala, Petr. "Tepelně-hydraulický a pevnostní výpočet výměníku tepla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-228941.
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Main object of the work is stress analysis of specific parts of tube and shell heat exchanger by using MKP. Each part is judged by two different computation methods. The method based on computation values and the method nearing real condition of operation of device. To approach real load are in the work made basic heat transfer computations for entire device and for analyzed part are computed boundary conductance by using CFD.
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Hladík, Petr. "Experimentální a výpočtové stanovení součinitelů přestupu tepla pro části průmyslové parní turbíny od firmy Siemens, s.r.o Odštěpný závod Industrial Turbomachinery." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231812.
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The subject of this diploma thesis is experimental and numerical assessment of the heat transfer coefficients during condensation of water steam in simplified parts of an industrial steam turbine. This simplified part is a pipe with circular cross section, which is often used in simulations of processes inside the steam turbine. The first part of thesis describes theoretical basics of heat transfer during conduction, convection and condensation. The content of other chapters is description of methods used to determine heat transfer coefficient. These are: ex-perimental analysis performed on a measuring device and evaluated using finite element ana-lysis (FEA), computational fluid dynamics analysis (CFD) in ANSYS CFX and analytical calculations of heat transfer coefficients using mathematical models for condensation. Thesis is concluded by validation and comparison of obtained results.
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Nejedlý, Pavel. "Návrh a pevnostní kontrola senzoru pro měření teplot a sil při válcování za tepla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228581.
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In the process of hot rolling is roll surface thermo-mechanically stressed. To define lifetime of roll or to increase it by change of thermal mode, temperatures and forces acting on this roll need to be known. For this purpose should be used sensors, that are placed near by surface of roll. Aim of the first part of diploma thesis is to debug 2D computing model (MKP) to achieve the match of temperature graphs with experimentally measured values, which was recorded by temperature sensors in real process of rolling. In the second part the same temperature boundary conditions are applied on 3D model, which is used to solve mechanical strength check of the temperature sensor. The last part of thesis is design and verification of mechanical strength of the designed force sensor. The used boundary conditions were acquired in Laboratory of heat transfer and flow. The computing system ANSYS 11 is used to design a model of geometry and numerical calculation. This diploma thesis will be used as donating solution for the granted project, which started in this year with Laboratory of heat transfer and flow partnership.
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Luks, Tomáš. "Okrajové podmínky ve válcovací mezeře při válcování za tepla a za studena." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-255769.
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Boundary conditions in the roll gap play an important role in modelling of rolling processes. In the roll gap we can observe the following: changes of rolling pressure, changes of relative velocity, influences of oxides and lubrication, etc. When taking into account all conditions mentioned above the determination of the boundary conditions is not trivial and extensive measurements are necessary. Therefore, this thesis is dealing with design of temperature and force sensors specified for the determination of friction coefficient and heat transfer coefficient in contact. The temperature sensor with an installed thermocouple measures subsurface temperature for a given depth; and then the inverse heat conduction task is used to compute temperature and heat flux on the surface. Several temperature sensors were designed and used for measuring in pilot mill and industrial rolling mill as well. The thermal responses of different sensors were compared in the numerical simulations. The inverse calculations were tested for various rolling conditions. A durability of the sensors was also studied in industrial rolling conditions. The contact stresses in the roll gap were measured by a pin, which was in direct contact with the rolled material. The forces on the top of the pin were measured by a three-axes piezoelectric force transducer and recalculated to the contact stress and friction coefficient. The sensor was implemented in a work roll and tested when rolling aluminium and steel slab for different rolling conditions. The results were compared with the integrative force sensor ROLLSURF.
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Mifek, Roman. "Výpočty kondenzátorů páry." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230736.
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This thesis deals with the calculation procedures for determining the heat transfer coefficient for steam condensers. The first section provides a basic overview for industrial steam condensers and possible procedure for selecting the appropriate type of tube condenser. The next section describes the types of condensation and equations for determining the heat transfer coefficient for various geometries of tubular condensers. In the final section there is performed practical calculation of condenser in Maple software using the above relations. The results obtained in this calculation are compared with the results obtained by professional computational software Chemcad and HTRI.
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Bellerová, Hana. "Rozvoj inverzních úloh vedení tepla se zaměřením na velmi rychlé procesy v mikroskopických měřítcích." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233976.
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The inverse heat conduction task is solved to determine boundary condition of the heat equation. This work deals with the ways how to increase the accuracy of the results obtained by solving inverse task based on the Beck sequential algorithm. The work is focused on the boundary condition changing very fast. This boundary condition is determinable with difficulty. It is shown that the placement and the type of the thermocouple play major role in accuracy of the calculation. The frequency of measuring and the discriminability of used devices also play a role as well as the setup of parameters in the inverse task. The election of mentioned parameters is described with regard to the speed of cooling. Knowledge from the theoretical part of the work is applied in the experimental part. The cooling intensity is investigated during spraying of the steel sample by water with nanoparticles Al2O3, TiO2, Fe and MWNT at three different concentrations. The experiments were carried out for three spray heights (40, 100, 160 mm), three flow rates (1, 1.5, 2 kg/min) and two types of the nozzle (full cone and solid jet). Surprisingly, the cooling intensity by using nanofluids is lower about 30% in comparison to the cooling intensity of pure water. But there was an exception. The cooling intensity of 1 wt.% of carbon nanotubes in water falling from the full cone nozzle placed in distance of 100 mm from the steel surface was higher about 174%. Finally, the reasons of the behavior of nanofluids are discussed.
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Kvapil, Jiří. "Tepelný odpor v kontaktu těles za vysokých teplot." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-255771.
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Nowadays numerical simulations are used to optimize manufacturing process. These numerical simulations need a large amount of input parameters and some of these parameters have not been sufficiently described. One of this parameter is thermal contact resistance, which is not sufficiently described for high temperatures and high contact pressure. This work describes experimental measuring of thermal contact resistance and how to determine thermal contact conductance which can be used as a boundary condition for numerical simulations. An Experimental device was built in Heat Transfer and Fluid Flow Laboratory, part of Brno University of Technology, and can be used for measuring thermal contact conductance in various conditions, such as contact pressure, initial temperatures of bodies in contact, type of material, surface roughness, presence of scales on the contact surface. Bodies in contact are marked as a sensor and a sample, both are embedded with thermocouples. The temperature history of bodies during an experiment is measured by thermocouples and then used to estimate time dependent values of thermal contact conductance by an inverse heat conduction calculation. Results are summarized and the dependence of thermal contact conductance in various conditions is described.
10
Ondroušková, Jana. "Rozvoj inverzních úloh vedení tepla řešených s využitím optimalizačních postupů a vysokého stupně paralelizace." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234338.
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In metallurgy it is important to know a cooling efficiency of a product as well as cooling efficiency of working rolls to maximize the quality of the product and to achieve the long life of working rolls. It is possible to examine this cooling efficiency by heat transfer coefficients and surface temperatures. The surface temperature is hardly measured during the cooling. It is better to compute it together with heat transfer coefficient by inverse heat conduction problem. The computation is not easy and it uses estimated values which are verified by direct heat conduction problem. The time-consuming of this task can be several days or weeks, depends on the complexity of the model. Thus there are tendencies to shorten the computational time. This doctoral thesis considers the possible way of the computing time shortening of inverse heat conduction problem, which is the parallelization of this task and its transfer to a graphic card. It has greater computing power than the central processing unit (CPU). One computer can have more compute devices. That is why the computing time on different types of devices is compared in this thesis. Next this thesis deals with obtaining of surface temperatures for the computation by infrared line scanner and using of inverse heat conduction problem for the computing of the surface temperature and heat transfer coefficient during passing of a test sample under cooling section and cooling by high pressure nozzles.