National Repository of Grey Literature 137 records found  beginprevious111 - 120nextend  jump to record: Search took 0.00 seconds. 
Temperature Profile in Reflow Soldering and Influence of Different PCBś and ComponentsThermal Capacities
Procházka, Martin ; Špinka, Jiří (referee) ; Starý, Jiří (advisor)
This thesis mainly deals with the prediction of temperature on the components and the PCB during reflow soldering. The theoretical part describes the particular solder reflow process, types of heat transfer and temperature profiles. The practical part is divided into forecasting temperatures if the conveyor is stopped and the temperature predictions when the conveyor is in motion. In both parts of the measured temperature is compared with the predicted temperatures, which show the success rate of prediction. The last part of this work is part of the simulation, which helps in proper understanding of the issues discussed.
Investigation of temperature change in lead-acid accumulator for HEV
Tošer, Pavel ; Křivík, Petr (referee) ; Bača, Petr (advisor)
The oldest and also most used type of secondary cells is lead-acid accumulator. Basic functional principle stayed same as in foundation time, only operation parameters are still improving (for example one of the most important is lifetime). Significant technical problem is temperature of lead-acid battery and her influence on functionality and running reactions. Master thesis is focused on this section, when is necessary to evaluate new pieces of knowledge in development. The work deals with description existing types of accumulators, further deals with theory of temperature balance and in the end by measured datas and theirs analyzing.
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.
Optimalisation of thermal properties of solar cell modules
Dohnalová, Lenka ; Matiašovský, Peter (referee) ; Zmeškal, Oldřich (advisor)
The topic of presented diploma thesis is study of thermal properties structures of photovoltaic cells. The main goal of this thesis is study of ways of heat spreading from volume and planar materials (conduction, convection and radiation). Then it is needed to determine contributions of heat spread from laminated photovoltaic cell and compare them to results measured by transient pulse method, step wise method and with thermo-camera using. At the beginning of this thesis it will be needed to define heat and ways it’s spread. Heat is closely connected with temperature. That is reason why will be there spoken about temperature and methods of its measuring. Than there will be defined basic thermo-physical parameters of materials. Thermo-physical parameters of materials will be measured by transient methods that will be characterized later and by thermo-camera. This thesis deals with photovoltaic cells, so there will be described their structure, properties, utilization and way of their production. Subsequently after the definition of all needed terms the experimental part of this thesis will be introduced. It will be needed to characterize measured volume material and define its thermo-physical parameters. Using the pulse transient method, step wise method and thermo-camera there will be measured the thermal response of PMMA sample, nonlaminated photovoltaic cell and also samples of laminated photovoltaic cells. Findings of all described methods will be finally compared.
Power - plant
Studený, Jan ; Severa, Zdeněk (referee) ; Mléčka, Jan (advisor)
The "POWER - PLANT" deals with the rehabilitation of the former Central Power Conversion and Dale Schoeller (Nejedly I and III) in the village Libušín Mine. Will be newly designed for building the power plant technology with progressive fluidized bed boiler to biomass steam turbine with an output of 7 MW and absorption (trigeneration) unit producing heat, cooling and electricity, which also will function as a cooler primary circuits. The source of water for the power plant will not only former mining pit Nejedlý I which is currently flooded drinking water at about 12 ° C. This system uses high efficiency embedded fuel (biomass), which is ultimately required less. A greater proportion of electricity generated and part of the heat will be distributed to the public network. In most areas will be proposed publicly accessible greenhouses of steel-aluminum construction filled ETFE foil forming the heat insulating membrane filled with air. The reason is to create conditions for the cultivation of tropical and subtropical plants. Greenhouses will be connected to the absorption unit power (underground meanders through which water will circulate), the ventilation shaft mine and mine water - therefore it will be possible to manage the conditions of the internal environment of the building without the influence of the season and especially without mounting other technological devices. It will provide for cooperation with the absorption unit for cooling the primary circuit - therefore eliminating the need for cooling towers or fans. The project will build a detached departments of the Faculty of Mechanical Engineering in Prague - Institute of progressive technologies and systems for energy and the Faculty of Agronomy and Natural Resources CULS. The reason is to allow students and scientists actively and in practice mainly participate in the operation and especially the development of the issue. The public in the area besides themselves open to the greenhouses indoor and outdoor thermal swimming. Part of the entrance hall is a bistro and foremost lecture hall. The aim is decentralized botanical-energy complex of buildings that produce electricity, heat, cooling, and biomass, and creating recreational, educational and research conditions.
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.
Design of Interior Heating Element
Juráňová, Zuzana ; Křenek, Ladislav (referee) ; Rubínová, Dana (advisor)
The topic of my bachelor´s thesis is design of interior heater. The aim is to design the kind of heater which will follow technical, ergonomic and esthetic requirements. There should be a possibility of using it in any room and it will be able to compete with the radiators on today´s market.
External thermal insulations and their energy-economic assessment
Sopůšek, Lubomír ; Kamenský, Petr (referee) ; Jaroš, Michal (advisor)
The aim of this bachelor theses is description of current thermal insulating materials by energetic aspect and subsequent comparison of the costs of acquisition. There is also included method of assessment and list of advantages and disadvantages of each material.
Heat storage in solar thermal systems
Sedmidubský, Petr ; Hejčík, Jiří (referee) ; Charvát, Pavel (advisor)
This bachelor´s thesis deals with heat storage in solar thermal systems. The first part of the thesis is devoted to the solar energy. The problems with its use are described in this part. The second part is devoted to solar thermal systems. Various types and designs of solar thermal systems are described in this part. The third part of thesis is devoted to the various types of solar thermal systems. The principle of their operation, advantages, disadvantages and the possibility of their practical use for each type is describe in this part.
Heat pumps for heating and hot service water preparation
Valášek, Martin ; Hrnčířová, Michaela (referee) ; Kracík, Petr (advisor)
This bachelor’s thesis is aimed to describe heating and water warming in the detached houses by basic technical devices and there are suggested various types of heat pumps for a particular object. These heat pumps are compared technically and economically. In the beginning of the thesis there is a summary of the possible ways of the house heating and water warming systems, such as heating by electric power, by gas, by solid fuel or the centrally distributed heating. Then the thesis concentrates on heat pumps. There are described various types of heat pumps, also their advantages and disadvantages. There were chosen four main types of heat pumps – air/water, air/air, water/water and earth/water – and with each type there’s constructed a plan for a low-energy house heating. This house is located in Vyškov and there’s thermal loss of 6 kWh and water-warming of a capacity of 260 l per day. At last there were used economical calculations, which shown, that the water/water heat pump has the shortest return rate in comparison with a gas-using heating system – 5 years. Considering the lifespan of the heat pumps – 10-20 years – all the heat pumps are profitable except for the air/air heat pump. The investment in this heat pump doesn’t return.

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