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Technique for Determination of Phase Changes in Moist Air Flowin a Blade Cascade
Vestfálová, M. ; Šafařík, P. ; Šimurda, David
The paper deals with theoretical and numerical tool for prediction of phase changes in moist air flow in flow systems. Partially solidified or liquidized steam in moist air appears to be a problem for peration wind tunnels, turbomachines, etc. Determination of phase change conditions is based on thermodynamic theory. Parameters of saturated homogeneous moist air are solved when expansion process is simulated at calculations. Conditions of saturation are successively verified and finally determined. Special phase diagram for moist air is designed.
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Phase Changes on Heat Exchanger Surfaces with Hollow Fibers
Kůdelová, Tereza ; Horák, Aleš (referee) ; Dohnal, Mirko (referee) ; Raudenský, Miroslav (advisor)
The thesis focuses on the polymer hollow fibres heat exchangers. The main object of the research is the formation and process of condensation on the outer surface of fibres and the effect of phase change on the heat transfer. The study deals with the influence of the geometry of the heat exchnager on the heat transfer and the condensation process. Fatigue tests of polymeric hollow fibres exchangers are also part of the work. The work provides an overview of the possible use of such heat exchangers in industrial applications associated with condensation.
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A Stefan problem of heat conduction with phase change and its exact solution
Kesler, René ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
This bachelor's thesis deals with analytical solutions of heat conduction problems with phase change which are known as classical Stefan problems. At the beginning a differential equation of heat conduction is derived and a mathematical model of Stefan problem is formed. The greatest attention is paid to the derivation of analytical solutions for cases in which these solutions are obtainable. The MATLAB environment was chosen for implementation of the obtained solutions. The thesis also includes a description of the program and its graphical interface in MATLAB. The applicability of the program is demonstrated in several phase change problems.
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Effect of soil water phase change on the soil temperature oscillation
Trlica, Ondřej ; Vlach, František (referee) ; Bečkovský, David (advisor)
This thesis deals with the study of soils freezing in terms of phase change of water contained in the soil strata on green roofs. The aim of this work is to verify the effect of phase transformation of water on the course of temperature oscillation. First described the basic characteristics of soils generally, and subsequently described processes occurring during phase transformation of water in the soil and has been carried out experimental verification of the effect of moisture in the soil on the course of temperature oscillation. In the overall evaluation of the work, an analysis of the effect of phase change water in soil on the course of temperature oscillation and the resulting conclusion of work.
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Study of passive stabilisation of building materials temperature
Šebek, Jan ; Pavlík,, Zbyšek (referee) ; Zmeškal, Oldřich (advisor)
The topic of presented master’s thesis was study of passive stabilization of building materials temperature. The main goal of this thesis was measuring and characterization of the thermal properties of building materials, which are used to PCM technology. PCM technology is based on utilization of latent heat of phase change. At the beginning of this thesis it was needed to define physical principle of phase change, then the most usable PCM chemicals (e.g. paraffin, Glauber’s salt, hexahydrate calcium chloride) and their basic physical properties (especially thermo-physical), background research of building materials with PCM and also the methods of thermo-physical properties measurement. It was also needed to characterize measured building materials and define theirs thermal parameters; because the values of thermal parameters of measured samples were compared to these values. In the experimental part of my thesis are measurements of material thermal analysis, which are methods, where the properties of materials are studied as they change with temperature. I had used to differential scanning calorimetry, transient pulse method and other methods, which are usable for thermo-physical properties measuring and characterization. I have been much interested in properties of measured material, which were specific heat capacity, temperature diffusivity, heat conductivity and phase change temperature (the melting point of PCM). At the end of my thesis the findings of all methods were finally summarized, compared and commented.
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