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Thermomechanical tire model
Vaníček, Jan ; Štětina, Josef (referee) ; Porteš, Petr (advisor)
This diploma thesis is about thermomechanics of passenger car tires. The research part dealing with existing tire models is followed by the practical part. The practical part is based on the designs of thermomechanical models. The first model determines a dependence of temperature on the air pressure inside a tire when a temperature changes. The second thermomechanical model captures all the heat fluxes which affect a tire while a vehicle is in motion. The third thermomechanical model calculates temperatures of parts of the tire during driving tests. All models are programmed in MATLAB.
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Air cooled condenser
Bochníček, Ondřej ; Kracík, Petr (referee) ; Pospíšil, Jiří (advisor)
This master´s thesis deals with an air cooled condenser. The specific attention is focused on the condenser in the Brno´s waste-to-energy plant SAKO. The general process of calculation of the heat transfer coefficient is introduced, which is the base for the calculation of the condenser´s output. This process is later used for the calculation of a specific condenser. A considerable part of the thesis is concentrated on the analysis of behavior of the condenser of SAKO in various conditions from the theoretical point of view and then also in terms of real operation using provided operational data.
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Thermal-hydraulic calculation and stress analysis of a heat exchanger
Fiala, Petr ; Létal, Tomáš (referee) ; Nekvasil, Richard (advisor)
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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The heat build-up of tap-off units of busbar trunking system in relationship to their surfacing.
Forejtník, Jan ; Radil, Lukáš (referee) ; Foral, Štěpán (advisor)
This study is dedicated to the effect of surface modification on lid warming of busbar trunking system BD2 which is manufactured by Siemens company in Mohelnice town (CZ). By using experimental methods, it investigates heat transfer by radiation and natural convection. It evaluates which type of surface modification is more effective by transfer heat. This study uses a method of emisivity comparison and a procedure given in standards for heat up test afterwards. It led to recognition, that various colour shades used on busbar system have similar high emissivity. Smooth colour spraying transfers heat a bit more effectively than rough colour spraying. Outputs of supplementary measurements give basis for numerical simulations in SolidWorks software. Numerical analysis assists to interpret results, for example by sensitivity study of heat transfer depending on emissivity.
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Design of Experiment for Inverse Heat Transfer Problem
Horák, Aleš ; Pavliska,, Martin (referee) ; Štětina, Josef (referee) ; Raudenský, Miroslav (advisor)
this thesis complex inverse heat transfer problem, which is focused on optimal design of experiment, is studied. There are many fields and applications in technical practice, where inverse tasks are or can be applied. On first place main attention is focused on industrial metallurgical processes such as cooling of continues casting, hydraulic descaling or hot rolling. Inverse problems are in general used to calculate boundary conditions of differential equations and in this field are used to find out Heat Transfer Coefficient (HTC). Knowledge of numerical approximation of precise boundary conditions is nowadays essential. It allows for example design of optimized hot rolling mill cooling focused on material properties and final product quality. Sequential Beck’s approach and optimization method is used in this work to solve inverse heat transfer problems. Special experimental test bench measuring heat transfer intensity was developed and built to full fill specific requirements and required accuracy. There were four different types of thermal sensor applied and studied. Those sensors are in usage in Heat Transfer and Fluid Flow laboratory (Heatlab) at various experimental test benches. Each specific sensor was tailored in Heat Transfer and Fluid Flow Laboratory to specific metallurgical application. Fist type of sensor was designed to simulate cooling during continuous casting. Second sensor is used for experiments simulate hot rolling mill cooling, while third sensor is designated for experiments with fast moving hot rolled products. Last sensor is similar to sensor type one, but thermocouple is located parallel to cooled surface. Experimental part of this study covers series of measurements to investigate Heat Transfer Coefficient (HTC) for various types of coolant, cooling mixtures and spray parameters. Results discovered in this study were compared with published scientific articles, and widely extend the knowledge of cooling efficiency for commonly used
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EFFECT OF HIGH PRESSURE WATER BEAM PARAMETERS ON QUALITY OF DESCALED SURFACE
Vavrečka, Lukáš ; Toman,, Zdeněk (referee) ; Pavliska,, Martin (referee) ; Horský, Jaroslav (advisor)
This work is focussed on hydraulic descaling of hot surfaces. Hydraulic descaling is a process when layers of oxides are removed from hot steel surfaces during continuous rolling. High pressure water beam is used. Quality of descaled surfaces is important for final quality of rolled product. Insufficient descaling causes drop of final quality, degradation of rolls and lost of yields. High-pressure water beam has two effects on a scale layer. The first effect is mechanical caused by impact pressure. The second one is a relatively intensive thermal shock depending on a set of parameters (water pressure, nozzle type, distance from the surface, inclination angle, speed of product moving). There are a lot of theories about principles of scales removing. Main task of this work is to make it clear which theory is acceptable and which is just ,,theory”. For this purpose mathematical modelling and experimental work were used. In experimental part, three types of experimental measurement were done. First one, measurement of dynamical effect of water beam – impact pressure. Second one, measurement of temperature drop when a product is passing under the nozzle. Measured data (temperatures) from this measurement are evaluated with inverse task and heat transfer coefficient is obtained. And the third experimental measurement is simulation of whole process of descaling. Quality of descaled surfaces is valuated according to amount of remained oxide scales. Data from firs and second experimental measurement are used as boundary conditions for mathematical modelling. For mathematical simulations, FEM (finite element method) system ANSYS was used. Obtained data from experimental measurement were applied on 2D and 3D models of basic steel material with layer of scale. Influence of theses data on final temperature, stress and strain fields were observed.
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Influence of the oxide layer on the cooling of steel surfaces
Resl, Ondřej ; Pohanka, Michal (referee) ; Chabičovský, Martin (advisor)
This thesis deals with the influence of the oxide layer on the spray cooling of steel surfaces. As part of the work steel samples with oxide layer are made and the thickness, porosity and surface roughness of this layer are characterized. The average thermal conductivity of porous oxide layer is determined for different regimes of oxidation. Further, the influence of the oxide layer on the heat transfer coefficient during the spray cooling is experimentally investigated on created samples and the basic numerical simulation of the cooling is done for selected experiment with oxide layer. The thesis also contains theoretical introduction to given issue.
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Development of Inverse Tasks Solved by Using the Optimizing Procedures and Large Number of Parallel Threads
Ondroušková, Jana ; Skarolek, Antonín (referee) ; Brestovič, Tomáš (referee) ; Horský, Jaroslav (advisor)
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.
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The influence of inclination air cooled tubes in the condensation
Kotas, Dan ; Pospíšil, Jiří (referee) ; Kracík, Petr (advisor)
Bachelor´s thesis deals with condensation in inclined tube in air-cooled condenser. The aim of the thesis is to describe different types of condensers including conections into a heat diagram. The next goal is to design a matematical model of air-cooled condensation of steam in inclined tube. The thesis also includes a design of an experimental setup to verify the mathematical model.
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Design and stress analysis of temperature and force sensor in hot rolling process.
Nejedlý, Pavel ; Pohanka, Michal (referee) ; Horský, Jaroslav (advisor)
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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