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Study of Thermal Properties of Materials for 3D Printing
Lapčíková, Tereza ; Menčík, Přemysl (referee) ; Zmeškal, Oldřich (advisor)
The aim of this bachelor thesis was to study thermal properties of materials used for 3D printing (so-called filaments), especially a polylactic acid (PLA). Within the theoretical part there was performed the literature review focused on the description of different methods of 3D printing including the summary of suitable materials for these technologies. In particular, we focused on the preparation of PLA, its summarization of its chemical, physical and thermal properties and its practical use in 3D additive printing manufacturing, e.g. in biomedical applications. In the experimental part, PLA samples of different thicknesses were prepared by 3D printing technique and thermal properties such as thermal capacity and thermal conductivity were determined. It was found that thermal conductivity of studied material was 0,128 W/m/K and specific heat capacity 1335 J/kg/K. These values corresponded to the once given in the literature.
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Srovnání lineárního a nelineárního výpočtu teplotního pole v obvodovém plášti dřevostavby
Dziamidau, Dzianis
The bachelor thesis deals with the comparison of the linear and nonlinear principle of calculation of the temperature field in the circumferential shell of wooden structures using 1D and 2D simulation in software based on the finite element method. The essence of this work is to determine the difference between these two ways and to find out if this difference in methods is at all relevant to real life. After the results were processed, it was found that the difference between these methods was not, but taking into account the presence of moisture the difference appeared and I would say the essence. The results show that wood moisture influences not only the values of the heat transfer coefficient but also the final result, such as the interior temperature or heat loss during heating.
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Roubená dřevostavba se zateplením
Foltýn, Pavel
The subject of this diploma thesis is the design of a timbered bungalow family house for a four-member household. The design works with current and future requirements of thermal properties of the perimeter shell. The thesis also deals with the problems of the selected construction system of the peripheral shell as well as with the basic constructional details. The processing also includes an assessment of structures in terms of the thermal properties’ requirements for the given structure. The thesis proposes several layout solutions of the object and their mutual comparison. In addition, the thesis deals with an issue and subsequent solution of the use of water from several sources. The work contains complete drawing documentation for building permits, technical reports and proof of energy performance of buildings.
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Financial analysis of Renewable energy
Kožík, Martin ; Hobst, Leonard (referee) ; Hrabová, Kristýna (advisor)
This thesis is focused on renewable energy sources, which are currently and increasingly used. Primarily for passive and low-energy houses. The principles that apply to heat pumps and solar collectors with thermal storage, which are suitable for new or older buildings, are described in detail. The thesis analyzes the thermal properties of the object under consideration and the proposed heat pump with its calculation and determination of the payback period of the investment in dependence on the analysis of energy price development in the las 10 years.
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Study of Electric and Dielectric Properties of Alkali-Activated Aluminosilicate with Increased Electrical Conductivity
Florián, Pavel ; Pavlík, Zbyšek (referee) ; Matiašovský, Peter (referee) ; Zmeškal, Oldřich (advisor)
This dissertation deals with the study of electric and dielectric properties of composite structures on the base of alkali-activated aluminosilicates with admixtures of various carbon particles. These materials fabricated from alkali-activated blast furnace slag, quarz sand, natrium water glass as alkali activator, water, dispersant and small amount of carbon admixture (carbon black, graphite powder, carbon fibers or carbon nanotubes) to increase electric conductivity may be used for example to construction of snow-melting, deicing and self-monitoring systems. Their current-voltage characteristics and impedance spectra were used for determination of electric and dielectric properties of these structures. The equivalent circuits were used for evaluation of impedance spectra. The results were correlated with thermal properties of these structures.
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Thermal properties of high performance fibre reinforced concrete
Pecháčková, Kateřina ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
This diploma thesis is focused on the study of the thermal properties of high-performance fiber reinforced concrete HPFRC. The composites are based on a combination of steel and polymeric fibers. Typical properties of these materials include high mechanical strength, water resistence and salt penetration. HPFRCs are mainly used in the construction industry to build tall buildings. The differential transient method was used to study thermophysical variables. The theoretical part of the thesis described the types of concrete, their production, and their properties. Furthermore, thermophysical quantities and methods of their determination (stationary and transient methods, thermal analysis) are defined in the thesis. The aim of the thesis was to determine thermal properties, namely thermal conductivity and specific heat capacity. The results of the thesis can reveal changes in the composition of studied materials as well as critical temperatures for damaging the materials.
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Study of thermal properties of sucrose
Pecháčková, Kateřina ; Lucie, Trhlíková (referee) ; Zmeškal, Oldřich (advisor)
This work is focused on the study of thermal properties of materials that are used for accumulating heat on the basis of phase transition. These are mainly sugar alcohols (mannitol, erythritol) or carbohydrates (glucose) respectively. Thermal properties, thermal in particular, and thermal conductivity and specific heat capacity were measured in a wide range of temperatures comprising of the transformation from the solid to the liquid phase in the entire volume of substance. To study the temperature dependence of thermal properties, transient methods were used, that allow to determine the diffusion and relaxation time, thermal absorption coefficient and a parameter characterizing the properties of resources based on the fractal model of heat transfer (shape and the heating of the sample). Thermal parameters were determined from those values for defined ideal heat source (planar) and defined ideal heating (leap). There are results of three sucrose samples produced in the Opava refinery (unrefined, refined, clean). Differences in their thermal properties were studied. In addition, thermal properties of a pure solution (commercial) of sugar in distilled water at different concentrations were studied (1:1, 3:1, 1:3). The results presented in this thesis may be used to more efficient use of thermal energy in heating of dwellings, both with the use of solutions, which have a higher heat capacity than water and also with the use of phase transformation.
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Verification of computer simulation in the field of thermal properties of foundry moulds
Šupa, Jan ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
This diploma thesis deals with thermal qualities of moulding mixtures of foundry mould of various types of sand grains and a computer simulation of the solidification of the cast. The aim of this work is to compare the values of thermal qualities of moulding materials bonded with water glass taken in experimental measurements to the values of thermal qualities of moulding materials connected with organic binding agent contained in simulation software. A sample cast will be moulded in order to evaluate cooling capacities of individual moulding mixtures according the shift of thermal axis. These results will consequently be compared to the results of the simulation.
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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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Study of thermal properties of selected coloids
Křivánková, Kateřina ; Krouská, Jitka (referee) ; Zmeškal, Oldřich (advisor)
The bachelor thesis is focused on the study of the thermal properties of colloidal systems, especially the properties of emulsions (water, oil), which can be used in the cosmetic industry as an essential component of various lotions and creams and in the food industry. In the introduction the first defined thermo-physical processes (conduction, convection and radiation) and temperature measurement (stationary, transient). Furthermore defined physical parameters (heat and thermal conductivity, heat capacity), that are determined using transient methods. The measured data were collected and analyzed by using the EMA (Electrical Measurement Analyser) and the HarFA (Harmonic and Fractal Image Analyser). The results will be used to determine the optimum conditions for the production of cosmetics and dietary supplements.
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