• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 54
  • 29
  • 13
  • 6
  • 3
  • 3
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 133
  • 133
  • 46
  • 24
  • 21
  • 18
  • 17
  • 17
  • 17
  • 16
  • 16
  • 15
  • 14
  • 14
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Analýza solární energie ze zdrojů Evropské unie v Jihočeském kraji / The Analysis of Support of Solar Energy in Jihocesky Kraj by the European Union

PECHLÁT, Vít January 2010 (has links)
This dissertation called The Analysis of Support of Solar Energy in Jihocesky Kraj by the European Union is focused right on one field of alternative sources of energy, which is very debated topic these days. The purpose of this dissertation paper is to describe the current situation in the exploitation of solar energy in Jihočeský kraj. Afterwards, the evaluation of photovoltaic power station to measure if the capital investment into alternative sources of energy presents profitable chance.
82

State-of-the-art development platform for hydropower turbine governors

Näsström, Joakim January 2017 (has links)
Hydropower is a flexible energy source that is essential for balancing the electrical power system on all timescales, from seconds to years. In addition to intra-hour regulation, it provides frequency containment reserves (FCR-N,FCR-D) and frequency restoration reserves (mFRR, aFRR) to the grid. The turbine governor is a device responsible for controlling the power output and delivering frequency control to the system. The aim of this Master’s Thesis project is to develop a new hydropower turbine governor in MATLAB/Simulink, which contains all critical functionality from the existing governor and with the same performance. The new governor should as far as possible comply to the well-established communication standard IEC 61850. A working model of the turbine governor has been built in Simulink that supports normal operation with frequency control, start and stop, load rejection, operation mode as synchronous condenser and more. Validations of the model against data from Akkats powerplant shows that the model behaves as a real governor during normal operation. Validations of the start sequence showed deviations during sequence 3 and 4 which can be explained by usage of different PID parameters. Using IEC 61850 as a nomenclature and as a way of structuring functions in the governor has also been possible. Implementing the whole standard for communication, requires that the control system also is renewed according to IEC 61850. Certain functions, as sequencing has thus not been done according to the standard. MATLAB and Simulink provide tools for building, simulating and testing implementations of the turbine governor. The contributions this platform can provide are; ease of implementation, optimization and testing of control strategies. Simulink also provides a graphical interface, which reduce system complexity. An optimal implementation requires a hardware with support for Simulink to get a transparent platform. Ultimately, these benefits could result in better frequency quality at a lower cost, which is essential for successful and cost-effective integration of other renewable energy sources such as wind- and solar power.
83

Zhodnocení napojení JEDU na horkovodní síť města Brna / Case study on utilizing of heat from the nuclear power plant Dukovany in the district heating system

Kozel, David January 2010 (has links)
In this thesis, I was solved assessment of nuclear power plant Dukovany, conection to the hot water network to city Brno. For determine the size needful enforcement was necessary to establish the heat balance of needs of the city of Brno and the size of the heat supply options. After that it was possible to determine the dimensions of pipes and optimize his routes of due to the current state of land along the route of thermal power supply. Power supply parameters were chosen with regard to the possibilities of technology used for transmission of the media and the status quo for distribution of the city Brno. After pushing the power supply ahead of the city Brno into the pumping station Bosonohy, and second part of the solution was the connection to the backbone wiring SCZT heat to individual customers. The last point was elaborated design management system of heat from nuclear power plant and urban local based resources on current management of heat supply system using consumption diagrams SCZT.
84

The effect of natural organic matter on ultrafiltration and reverse osmosis membrane performance at Komati Power Station

Dladla, Zanele January 2013 (has links)
Komati Power Station has installed a membrane plant consisting of ultrafiltration, double pass reverse osmosis and continuous electro-deionisation to treat cooling tower blowdowns in order to produce demineralised water and to conduct sidestream chemistry control of the cooling water circuit. This plant has replaced the existing ion-exchange plant that was used for the production of demineralised water and thus serves to reduce the loading of mobile salts in the ash dam (90% reduction) by eliminating regeneration effluent from the ion-exchange plant. Due to oil contamination in the cooling water circuit (when oil from oil coolers leaks into the cooling water), the membrane plant was also designed to operate on raw water from either the Nooigdedacht or the Vygeboom Dam or a blend of both dams. This is considered to be an emergency intervention under abnormal conditions to prevent possible irreversible fouling of the membranes due to oil in the cooling water. The Nooigtedach Dam water contains high concentrations of organic matter and is also enriched with nutrients due to raw sewage influent into the Dam water. This poses a challenge with regard to treatment of the high fouling feed water on the membrane plant. Natural organic matter in water has the ability to foul reverse osmosis membranes. This adversely affects the operation of the reverse osmosis process. However, very little information is available regarding the fouling characteristics of natural organic material in the raw and cooling water at Komati Power Station for the reverse osmosis membranes. Therefore, a pilot study was undertaken to determine the influence of natural organic matter on membrane fouling, to optimise the process for the removal of natural organic matter and to assess the ability of two different reverse osmosis membranes to effectively treat the high fouling feed water at Komati Power Station. The ability of a polyethersulphone hollow-fibre ultrafiltration membrane system was first evaluated to remove natural organic matter in the feedwater, by conducting pilot tests, initially without coagulation of the raw water and thereafter with in-line coagulation for organics removal. Jar tests were conducted in the laboratory to determine the most suitable coagulant and dosage for turbidity and natural organic matter removal. Various coagulants were tested and, based on the results of the jar tests, a coagulant (U3000) was identified based on optimal removal of both total organic carbon and turbidity at a dosing level of 20 mg/L. During the operation of the ultrafiltration pilot plant, permeate flow; feed pressure and feed temperature were monitored. Performance of the ultrafiltration membrane was monitored in terms of flux versus time for operation with and without a coagulation process. The results indicated that there was very little total organic carbon removal (maximum removal of 4%) without coagulation and a slight decrease in flux. The flux declined as a result of fouling but could be recovered by performing hydraulic backwashes and CEB procedures. Permeate flux, however, could be maintained at about 90 Lmh (from 642 hours of operation). Since most of the organics passed through the ultrafiltration membrane, it was concluded that the loss in flux was due to colloidal fouling of the membrane. This was observed when the operation was carried out using raw water as feed as well as when cooling water was used. The total organic carbon removal increased to 30% when the plant was operated with inline coagulation. The flux remained relatively stable during the first 600 hours of operation and only decreased significantly during the last 200 hours of operation as a result of fouling. The reduction in flux prior to cleaning was less than the 15% (maximum flux decline of 9.9% during the test period) which is acceptable according to the industry norm of 15%. It appeared that flux could be maintained at around 90 Lmh which was about the same as when no coagulant was applied. The 30% total organic carbon reduction that was obtained was not sufficient to reduce the organics to the level of 6mg/L dissolved organic carbon that was specified by the membrane manufacturer for the standard brackish water reverse osmosis membrane. Two reverse osmosis membranes – the standard brackish water reverse osmosis membrane (BW30-2540) and the extra-low-fouling membrane (BW30XFR-2540) – were assessed in terms of their ability to remove dissolved organic carbon, ease of cleaning of the membrane and the ability to recover flux after cleaning. This was done to establish which membrane is more suited to Komati’s high-fouling feedwater. The evaluation of the performance of the two reverse osmosis membranes was conducted using pre-treated water (filtered water after in-line coagulation, anti-scalant and biocide dosing) as well as using water that was not pre-treated. During operation (under both conditions), the normalised permeate flux, conductivity, dissolved organic carbon and organics absorbing at UV254 were monitored. It was established that in terms of flux decline that the extra low-fouling membrane gave slightly superior performance to that of the standard membrane, achieving longer production runs (up to 5 days compared with 3 days achieved by the standard brackish water membrane) without requiring chemical cleaning. The low fouling membrane achieved better CWF recovery after the cleaning cycles (81.26% Lmh of the virgin membrane on the occasions when there was flux loss) compared to the standard membrane (restored to 77.35% of CWF of the virgin membrane) when using untreated feed water. This performance improved when pre-treated feed water was used and the low fouling membrane’s CWF regained after the CIP was 95.89% which was within the industry norm of a flux recovery of 95%, indicating that the CIP had been effective. It was determined that the TOC rejection of the low-fouling membrane was higher (average TOC rejection of 97%, maximum TOC rejection of 99%) than that of the standard membrane (average TOC rejection of 95.3%, maximum TOC rejection of 97%). Preliminary efforts to optimize the pre-treatment for organics removal in order to reduce organic loading for the RO membranes confirmed that the use of granular activated carbon and use of an organic scavenger resin might not be economically feasible due to the relatively quick TOC breakthrough (8910BV, approximately 18000BV and less than 18000BV for the Filtrasorb 300, Filtrasorb 400 and organic scavenger resin, respectively). Although further investigations should still be conducted, the preliminary results indicate that it would be beneficial to also identify other options that can be further investigated for optimization of organics removal at Komati Power Station. Decline in the normalised flux as well as the evidence of biofouling were witnessed during the pilot operation suggesting that the membranes were fouled. Autopsies were performed on both membranes to identify foulants responsible for the decline in flux that was observed during the pilot study. The results did not indicate an organic foulant on the membrane surface. Biofouling should however, be monitored in the main plant as this was suspected to have resulted in the flux decline during the pilot study. The low fouling membrane demonstrated a better capability to treat the Komati raw and cooling water and would be expected to achieve lower operating costs for the plant (CIP costs and membrane replacement costs) while achieving better organics removal and it is therefore recommended that the low-fouling membranes be used at Komati Power Station as they are superior to the standard membrane and the cost of the low-fouling membranes is comparable to that of the standard membrane. While this would provide somewhat better performance than that obtained with the standard brackish water membranes, it is proposed that further investigation into pre-treatment optimization for organics removal as well as more efficient cleaning solutions be investigated to improve the performance and economics of the main water treatment plant at Komati power Station. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Chemical Engineering / unrestricted
85

Monitoring of power station steels using electromagnetic sensors

Karimian, Noushin January 2014 (has links)
With the world’s aging power generation network, especially in Europe and the United States, life-extension of steel plant components is increasingly a critical issue, as components are exposed to high temperatures and pressures during their lifetime, potentially resulting in carbide coarsening, making them prone to creep cavitation, possibly leading to component failure. Therefore, in order to evaluate the likelihood of component failure, non-destructive testing and evaluation procedures must be developed to properly assess the level of degradation in power station steels and ensure that end-of-life conditions are not reached. Electromagnetic (EM) inspection techniques have the potential to assess the level of degradation in power station steels through in-situ measurements. This research work introduces and examines a novel approach in the development of an EM sensor system for long term use. Specifically, it focuses on employing the developed EM sensor system technology in the monitoring of microstructural variations in power generation steels (such as boiler tubes) for in-service monitoring and evaluation during maintenance periods. In this work, controlled measurement of the EM properties (differential permeability) of cylindrical samples, machined from power station pipes (P9) and tubes (T22) in different states of degradation were carried out using two different EM sensor systems. Analytical and numerical methods (Finite Elements) were employed to calculate the sensor response to the samples and EM properties inferred by fitting the models to the measured results. The results from a closed magnetic loop sensor system were also considered, where the magnetic hysteresis curves for the steel samples were measured, from which relative incremental permeability values were obtained. It was found that the incremental permeability values measured by this system were connected to the differential permeability values obtained from the induction spectroscopy. Strong correlations have been drawn between microstructural changes (quantified using Vickers hardness measurements) in heat treated samples and EM properties (incremental and differential permeability). Finally, correlations established using the lab-based closed magnetic loop system are transferred to real-world samples, such as grade 91 open pipe / tube specimens. The measurement results verify that the techniques employed for measuring the EM properties of rod samples produce similar results for the open tube samples, demonstrating the viability of application of EM methods for assessment and monitoring of open power station pipes and tubes in-situ.
86

Podnikatelský plán výstavba fotovoltaického systému společnosti SOLAT, s.r.o. / The business plan - building of photovoltaic system of company SOLAT, s. r. o.

Štrynclová, Monika January 2008 (has links)
The graduation theses is concerned with elaboration of business plan whose theme is building of solar power station in locality of Velké Hamry. The aim of graduation theses is evaluation of building and operation of solar power station through the medium of methods which make for assessments of investment as well as entire business plan processing which should be used in application for granting of credit and in application for financial support of Operational program of Enterpreneurship and Innovation.
87

Projektové financování investičních projektů se zaměřením na projekty z oblasti obnovitelných zdrojů energie / Project Financing of Investment Projects in the field of Renewable Energy Resources

Karnetová, Lucie January 2008 (has links)
My thesis is focused on Project Financing of Investment Projects in the field of Renewable Energy Resources. The theoretical section, see Chapter Two, characterises the nature of project financing, parties, principles for successful project financing, types of capital invested in projects and their resources, risks, guarantees and securities. The practical (third) part of the thesis is oriented to specifics of project financing of Renewable Energy Resources. First of all principles for the assessment both of project bearers and projects in terms of quality are specified. Furthermore, principals for the assessment of financial terms of projects are given. The fourth and concurrently the final Chapter analyses a particular project in the field of renewable energy resources mostly from the financial point of view.
88

Mobilní fotovoltaická elektrárna / Mobile photovoltaic power plant

Klíč, Tomáš January 2018 (has links)
This diploma thesis is divided into two parts, namely the theoretical and practical part. In the theoretical part, the issue is dismantled from the current state of electric power, share the production of individual sources, the market for photovoltaic and mobile photovoltaic systems through the description of the theory of solar radiation and all the necessary components to build the isolated photovoltaic power plant. The practical part deals with dimensioning, selection of suitable components and the actual one own design and implementation of a mobile photovoltaic power plant.
89

Výroba utahováku matice oběžného kola čerpadla / Manufacture of nut tightening device for reactor cooling pump's impeller

Rygl, Filip January 2020 (has links)
This thesis solves the problem of design and production of a special mounting device for the impeller nut of the main circulation pump GCN-317. The proposed device is intended to solve the problems associated with the mounting and dismounting of this nut. The work provides basic information about the Dukovany Nuclear Power Plant and VVER-440 systems in general, including their brief history. It also introduces the operational and legislative environment of the primary circuit of the nuclear power plant. It deals with the task and technical description of the main circulation pump and its overhaul. The following sections present the basic principles of construction of the device and an overview of its components with a description of their purpose and method of production. The last part of the thesis describes the function of the device and its verification and reports on its deployment.
90

Akumulace elektrické energie z obnovitelných zdrojů / Accumulation of electricity from renewable sources

Plíšek, Petr January 2021 (has links)
This diploma thesis deals with the issue of accumulation of electricity produced by renewable sources. The first part focuses on the description of possible ways of accumulation, especially with focus on those methods, that are suitable for renewable energy sources. The next part deals with the design of the accumulation energy in the compressed air for the selected photovoltaic power plant. The necessity of designing a particular method of energy storage, is also its technical and economic analysis, which is the content of the last part of the thesis.

Page generated in 0.0557 seconds