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The long-term accumulation of solar collectors and the subsequent use of the heat
Litera, Jiří ; Fiedler, Jan (referee) ; Kracík, Petr (advisor)
The aim of the thesis is the design and evaluation of the long-term accumulation of solar collectors and the subsequent use of the heat. The basic principles of the use of solar energy are introduced in the theoretical part as well as the list of available heat pumps, solar collectors moreover options for the accumulation of heat are evaluated. In the practical part the system of a long-term heat accumulation for a partially restored family house is designed, where accumulation into water or gravel are the two presented options. Solar energy is collected by solar collectors and accumulated in the long term storage. The system involves water to water or ground to water heat pump that reduces the temperature of the reservoir in order to increase the temperature difference of the system. Both options require a large volume of heat collecting, including large surface of solar collectors. Because of the high cost and spatial requirements the system shows to be hardly realistic in practice. For this reason an alternative solution of a family house heating system more suitable from the economic point of view is described. As a result it was proved that system of the long-term accumulation is not an appropriate solution for heating system of family houses and it is used in places with enough space for the accumulation such as high capacity trays or flooded mines. For existing family houses (partly insulated and with a heat source such as natural gas) the usage of the heat pump eventually supported by solar collectors appears as the most sensible solution. Such solution shows a return of investment from 14 to 25 years, and contributes to sustainable development and to reduction of non-renewable primary energy.
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Flow control in a hydraulic turbine draft tube
Litera, Jiří ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
Hydraulic energy is one of the most important sources in the world for electricity production. Nowadays the trend is to limit the production of the electricity from fossil fuels and to protect the environment. The main idea is to use more renewable energy sources such as wind and solar energy. Unfortunately, these alternative sources are strongly dependent on current weather conditions, which causes the instability of the electrical grid. Luckily pumped storage and hydraulic power plants provide the solution. However, it requires an extension of the operating range of the hydraulic machines. For that reason, the water turbines now operate over and extended range of regimes, that can be quite far from the best efficiency point. Hence two types of unstable two-phase flows in the Francis turbine draft tube occur: part load overload. This diploma’s thesis is focused on the Francis turbine operating at the part load. During part load conditions the helical vortex rope is being developed in the draft tube, it causes pressure pulsation and it can lead to the hydro-acoustic resonance, which damages the elements of the power plant. The aim is to eliminate the pulsation by jet control of the swirling flow in the draft tube. In the diploma’s thesis, various approaches to jet control of the flow in conical diffuser are tested using the computational fluid dynamics.
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Flow control in a hydraulic turbine draft tube
Litera, Jiří ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
Hydraulic energy is one of the most important sources in the world for electricity production. Nowadays the trend is to limit the production of the electricity from fossil fuels and to protect the environment. The main idea is to use more renewable energy sources such as wind and solar energy. Unfortunately, these alternative sources are strongly dependent on current weather conditions, which causes the instability of the electrical grid. Luckily pumped storage and hydraulic power plants provide the solution. However, it requires an extension of the operating range of the hydraulic machines. For that reason, the water turbines now operate over and extended range of regimes, that can be quite far from the best efficiency point. Hence two types of unstable two-phase flows in the Francis turbine draft tube occur: part load overload. This diploma’s thesis is focused on the Francis turbine operating at the part load. During part load conditions the helical vortex rope is being developed in the draft tube, it causes pressure pulsation and it can lead to the hydro-acoustic resonance, which damages the elements of the power plant. The aim is to eliminate the pulsation by jet control of the swirling flow in the draft tube. In the diploma’s thesis, various approaches to jet control of the flow in conical diffuser are tested using the computational fluid dynamics.
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The long-term accumulation of solar collectors and the subsequent use of the heat
Litera, Jiří ; Fiedler, Jan (referee) ; Kracík, Petr (advisor)
The aim of the thesis is the design and evaluation of the long-term accumulation of solar collectors and the subsequent use of the heat. The basic principles of the use of solar energy are introduced in the theoretical part as well as the list of available heat pumps, solar collectors moreover options for the accumulation of heat are evaluated. In the practical part the system of a long-term heat accumulation for a partially restored family house is designed, where accumulation into water or gravel are the two presented options. Solar energy is collected by solar collectors and accumulated in the long term storage. The system involves water to water or ground to water heat pump that reduces the temperature of the reservoir in order to increase the temperature difference of the system. Both options require a large volume of heat collecting, including large surface of solar collectors. Because of the high cost and spatial requirements the system shows to be hardly realistic in practice. For this reason an alternative solution of a family house heating system more suitable from the economic point of view is described. As a result it was proved that system of the long-term accumulation is not an appropriate solution for heating system of family houses and it is used in places with enough space for the accumulation such as high capacity trays or flooded mines. For existing family houses (partly insulated and with a heat source such as natural gas) the usage of the heat pump eventually supported by solar collectors appears as the most sensible solution. Such solution shows a return of investment from 14 to 25 years, and contributes to sustainable development and to reduction of non-renewable primary energy.
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