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  • 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.
31

Beneficiamento de finos de carvão por concentrador centrífugo - Falcon®

Siquela, Eduardo Armando January 2012 (has links)
O objetivo deste trabalho é de avaliar o desempenho do concentrador Falcon® no beneficiamento de finos de carvão. Para tal foi usada uma amostra de carvão ROM da mina LEÃO II. Nos ensaios foi usado o concentrador Falcon® modelo L40. As variáveis operacionais estudadas foram: a aceleração da centrífuga, a granulometria da alimentação e a pressão da água de fluidização. Para todos os ensaios realizados na faixa granulométrica -0,25mm as taxas de rejeição de enxofre variaram entre 42,55% e 69,51%, e a recuperação da matéria orgânica variou entre 65,79% e 95,85%. Na faixa granulométrica de -0,5+0,25mm o valor mínimo da rejeição de enxofre total foi de 53,63% e o máximo de 75,22%. A recuperação de matéria orgânica variou entre 57,77% e 90,86%. Já a rejeição de cinzas mostra as taxas mais baixas para a faixa granulométrica-0,25mm, que varia entre 11,78% a 46,87%, comparada à faixa granulométrica de -0,5+0,25mm que apresenta valores entre 29,98% e 60,42%. Em geral o processo mostrou-se mais eficiente quando operado com valores baixos de aceleração (78G), e pressão de água relativamente baixa (entre 4 e 8Psi). / This study aims to evaluate the performance of the Falcon® concentrator in beneficiation of fine coal. A sample from LEAO II ROM and a L40 Falcon® concentrator was used for all tests. Operating variables studied were: G forces, the feed particle size and the water backpressure. For the tests performed with samples of -0.25mm particle size, sulfur rejection rates ranged from 42.55% to 69.51%, and the coal recovery ranged from 65.79% to 95.85%. In the -0.5+0.25mm size fraction the minimum value of total sulfur rejection was 53.63% and a maximum of 75.22%. The recovery of organic matter ranged from 57.77% to 90.86%. The ash rejection shows the lowest rates for the -0.25mm particle size, ranging from 11.78% to 46.87%, compared to -0.5+0.25mm size fraction which has values between 29.98 % and 60.42%. In general the process was more efficient when operated at low values of G-Force (78G), and low water pressure (4 and 8Psi).
32

Beneficiamento de finos de carvão por concentrador centrífugo - Falcon®

Siquela, Eduardo Armando January 2012 (has links)
O objetivo deste trabalho é de avaliar o desempenho do concentrador Falcon® no beneficiamento de finos de carvão. Para tal foi usada uma amostra de carvão ROM da mina LEÃO II. Nos ensaios foi usado o concentrador Falcon® modelo L40. As variáveis operacionais estudadas foram: a aceleração da centrífuga, a granulometria da alimentação e a pressão da água de fluidização. Para todos os ensaios realizados na faixa granulométrica -0,25mm as taxas de rejeição de enxofre variaram entre 42,55% e 69,51%, e a recuperação da matéria orgânica variou entre 65,79% e 95,85%. Na faixa granulométrica de -0,5+0,25mm o valor mínimo da rejeição de enxofre total foi de 53,63% e o máximo de 75,22%. A recuperação de matéria orgânica variou entre 57,77% e 90,86%. Já a rejeição de cinzas mostra as taxas mais baixas para a faixa granulométrica-0,25mm, que varia entre 11,78% a 46,87%, comparada à faixa granulométrica de -0,5+0,25mm que apresenta valores entre 29,98% e 60,42%. Em geral o processo mostrou-se mais eficiente quando operado com valores baixos de aceleração (78G), e pressão de água relativamente baixa (entre 4 e 8Psi). / This study aims to evaluate the performance of the Falcon® concentrator in beneficiation of fine coal. A sample from LEAO II ROM and a L40 Falcon® concentrator was used for all tests. Operating variables studied were: G forces, the feed particle size and the water backpressure. For the tests performed with samples of -0.25mm particle size, sulfur rejection rates ranged from 42.55% to 69.51%, and the coal recovery ranged from 65.79% to 95.85%. In the -0.5+0.25mm size fraction the minimum value of total sulfur rejection was 53.63% and a maximum of 75.22%. The recovery of organic matter ranged from 57.77% to 90.86%. The ash rejection shows the lowest rates for the -0.25mm particle size, ranging from 11.78% to 46.87%, compared to -0.5+0.25mm size fraction which has values between 29.98 % and 60.42%. In general the process was more efficient when operated at low values of G-Force (78G), and low water pressure (4 and 8Psi).
33

Desenvolvimento de um sistema de controle de baixo custo para rastreamento de concentradores cilÃndrico-parabÃlicos / Development of a system of control of low cost for tracking of cylindrical-parabolic concentrators

Erilson de Sousa Barbosa 27 May 2009 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Um concentrador solar parabÃlico à um tipo de refletor usado para aumentar a intensidade da radiaÃÃo em uma superfÃcie. Para que ocorra a reflexÃo adequada da radiaÃÃo solar, o refletor parabÃlico deve constantemente rastrear a posiÃÃo do sol de tal forma que os raios solares sejam refletidos em um tubo que se encontra na posiÃÃo de foco da parÃbola. A proposta deste trabalho à desenvolver um sistema eletrÃnico de controle de baixo custo para concentradores parabÃlicos aplicados à refrigeraÃÃo e proporcionar autonomia ao equipamento. TambÃm à apresentado um sistema mecÃnico para acionamento do rastreador. Por ser parte de um sistema de refrigeraÃÃo, o tubo colocado no foco da parÃbola deve sofrer processos de aquecimento e resfriamento. O sistema à constituÃdo de uma placa de controle com um microcontrolador em seu nÃcleo, sensores de luminosidade e sensores limitadores de movimento e um motor de passo responsÃvel pelo acionamento da estrutura mÃvel do concentrador solar. AtravÃs do sistema desenvolvido, pode-se fazer com que sejam atingidas temperaturas em torno de 180ÂC na superfÃcie externa do tubo coletor colocado na posiÃÃo de foco da parÃbola / A parabolic solar concentrator is a type of reflector utilized to increase the radiation intensity on a surface. In order to have a proper reflection of solar radiation, the parabolic reflector should constantly track the sunâs position so that solar rays are converged to a tube that is at the focus position of the parabola. The purpose of this study is to develop an electronic control system for low-cost parabolic trough concentrators applied to refrigeration process, and to provide autonomy to the equipment. It also is presented a mechanical system to guide the tracker. As part of a refrigeration device, the tube placed at the parabolaâs focus should experiment heating and cooling processes. The electronic system consists of a control plate with a microprocessor at its core, motion limiting and light sensors, and a step motor responsible for move the solar concentrator structure. Through this developed system, temperatures close to 180oC can be reached on external surface of the heat adsorption tube, which is placed on the position of parabolaâs focus
34

Adaptor Development : An insight to interfacing with electrical energy meters

Castberg, Miro January 2011 (has links)
Since energy meters became more advanced and able to send data remotely, energy suppliers have had a need to keep their data managed. This gave birth to energy management systems which gather data from energy meters. However, for every type of meter there needs to be a specialization in the management system. Smart Metering Language (SML) is a protocol which was created to transfer meter data in as simple way as possible. Implementing the protocol would result in simpler and less vendor-specific solutions for energy management systems. This report follows the process of developing an adaptor between a device using the SML protocol and a system that manages energy meters. The thesis uses different parts of the development process in able to show specializations which were needed by the test device and its vendor.  The result sums up the experience of developing an adaptor and the specializations which are needed in the SML protocol.
35

A New Characterization Technique to Analyze Concentrator Photovoltaic Optical System Performance

Mcvey White, Patrick January 2017 (has links)
Concentrator photovoltaics is a promising renewable energy technology, especially for utility or large-scale deployments. Like all new technologies, it has obstacles and setbacks to overcome. More specifically, the optics in a concentrator photovoltaics system introduce non-uniform spatial and spectral illumination on the cell, which can change under different operating conditions. This work was put together to discover a new characterization technique capable of analyzing the performance of a concentrator photovoltaics and provide insight to the field on what is happening within the system, linking modeling results seen in the literature to these experimental outcomes. The thesis is composed of three journal papers written by the candidate, who’s contributions are outlined at the beginning of each chapter. In order to study the illumination profiles on the cells, a new method to characterize the optical components had to be developed. Previous version lacked the ability to control the temperature of the lens and had low spectral resolution of the irradiance profiles. To improve, a novel indoor measurement method was developed capable of spectrally imaging concentrator photovoltaics optics and recreate outdoor operating conditions in a controllable environment. With the calibrated system, our test-bench is capable of measuring the spectral distribution with a 10μm2 resolution and characterizing the output of a system to within 3%. Exploiting this experimental technique, the individual effects of module misalignment, cell to primary distance, and lens temperature was studied for three leading technologies associated with the three generations of concentrator photovoltaics optical architectures. Focusing on Fresnel-based concentrator optics, the performance of silicone on a glass module without a secondary optic is the most sensitive to operating conditions, where lens temperature can decrease the absolute efficiency resulting in a difference of 11% in the annual energy yield. The next two generations have secondary optics but are designed slightly differently. The truncated inverted pyramid, designed independently of the primary optic, favoured higher lens temperature values and there was only a difference of 1% in the energy yield calculation. The primary and secondary optics in the 4-fold Fresnel-Kohler are designed together, due to new development tools, and showed the highest stability under the different operating conditions, demonstrating that concentrator photovoltaics is on the right track to overcoming its onset issue. As the technology matures, future designs can improve on the issues characterized within this thesis.
36

Fotovoltaický článek pro koncentrátorový systém / Photovoltaic cell for concentrator system

Straškraba, Vojtěch January 2013 (has links)
The subject of this master’s thesis is to introduce concentrator photovoltaic systems. Main subject of presented work are photovoltaic cells and their features and characteristics. The work deals with physical fundamentals of solar cells, type of cells and their specifics and discusses possible treatment for achieving better characteristics of concentrator systems. In the practical part is realized measurement and analysis of electrical characteristics of 9 different monocrystalline silicon cells. From those is the most efficient cell chosen for further use as reference cell.
37

Demonstrační úloha zaměřující se na problematiku Smart Metering / Smart Metering demonstration demo

Gregor, Filip January 2021 (has links)
The thesis deals with PLC technology and issues with Smart Metering. In the theoretical part, a principle of technology's functionality and its advantages and disadvantages were described. In the experimental part methodology of data concentrator and electric meters was designed. In addition, extensive testing set according to capturing of DLMS communication, link quality influencing, reading registers of meters were realized. In the second experimental part limits of communications between broadband BPL modems were detected by the power line communication hardware channel emulator. Measurement of throughput, latency, frame loss passed off according to RCF 2544, RFC 6349 recommendation and according to the methodology of TCP Throughput In the last part, two laboratory exercises were created, first one deals with Smart Metering system and communication between the data concentrator and electric meters and the second one deals with communication among broadband BPL modems not only for Smart Metering purposes.
38

Flexibilní bezdrátový systém pro měření CO2 v budově / Indoor flexible wireless CO2 measure system

Válek, Vít January 2021 (has links)
Monitoring of the carbon dioxide concentration in the building is carried out for several reasons. One is to ensure hygiene conditions. With the advent of Bluetooth 5.0 came the support of mesh network technology, which is defined by the Bluetooth Mesh standard. By implementing this standard, we can create an extensive network of devices monitoring the concentration of carbon dioxide in the building. Based on the monitored concentration, we can control the air conditioning and ventilation of the spaces, ensuring that the hygiene conditions are met. Thanks to the compatibility of Bluetooth Mesh with Bluetooth Low Energy, it is possible to access individual nodes, e.g. from a mobile phone. The aim of this work is to design and implement a measuring system whose elements will communicate with each other using Bluetooth Mesh wireless technology.
39

Optimalizace difraktivních struktur pro koncentrátorový fotovoltaický panel / Optimization of diffractive structures

Chalupa, Petr January 2011 (has links)
This work is focused on the possibility of sunlight concentration on silicon dies or silicon stripes. The main aim of this work is the design and realization of the concentration element, or system, which is based on diffractive optics and optimized to achieve possibly high optical efficiency. The theoretical part deals with problems of photovoltaic systems and sunlight concentration. The practical part deals with design of optical microstructures and their realization by e-beam lithography using the electron-beam writer BS600. Microstructures created in the electron resist on silicon substrates or embossed into transparent materials are measured in the laboratory. We evaluated and compared their optical properties, which gives some feedback for further optimizations. Transparent elements are tested with real silicon dies and so overall properties of a prototyped photovoltaic module can be evaluated.
40

Konstrukce dvouosého solárního trackeru / The design of two axis solar tracker

Krejčí, David January 2011 (has links)
The purpose of this dissertation is to design the dual-axis solar tracker carrying the concentrator photovoltaic panels. The preamble of the dissertation shortly examines a photovoltaic cells development up to concentrators and the common support structures of solar power plants. The second part focuses on the engineering process itself. It includes the choice of the variant that suits best the requirements, the calculations of wind load and design of the various joints. The conclusion part is devoted to the evaluation, economy analysis of the construction and proposals for improvements.

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