A photovoltaic thermal solar collector (PVT) produces both heat and electricity from a single panel. PVT collectors produce more energy, for a given area, than conventional electricity and heat producing panels, which means they are a promising technology for applications with limited space, such as building integration. This work has been broken down into 3 subprojects focusing on the development of PVT technology. In the first subproject an experimental testing facility was constructed to characterise the performance of PVT collectors. The collectors under investigation were assembled by combining bespoke thermal absorbers and PV laminates. Of the two designs tested, the serpentine design had the highest combined efficiency of 61% with an 8% electrical fraction. The header riser design had a combined efficiency of 59% with an electrical fraction of 8%. This was in agreement with other results published in literature and highlights the potential for manufacturers of bespoke thermal absorbers and PV devices to combine their products into a single PVT device that could achieve improved efficiency over a given roof area. In the second project a numerical approach using computational fluid dynamics was developed to simulate the performance of a solar thermal collector. Thermal efficiency curves were simulated and the heat removal factor and heat loss coefficient differed from the experimental measurements by a maximum of 12.1% and 2.9% respectively. The discrepancies in the findings is attributed to uncertainty in the degree of thermal contact between the absorber and the piping. Despite not perfectly matching the experimental results, the CFD approach also served as a useful tool to carry out performance comparisons of different collector designs and flow conditions. The effect of 5 different flow configurations for a header collector was investigated. It was found that the most efficient design had uniform flow through the pipe work which was in agreement with other studies. The temperature induced voltage mismatch, that occurs in the PV cells of PVT collector was also investigated. It was concluded that the temperature variation was not limiting and the way in which PV cells are wired together on the surface of a PVT collector did not influence the combined electrical power output.

Submitted by Márcio Maia (marciokjmaia@gmail.com) on 2016-08-08T12:09:17Z No. of bitstreams: 1 arquivototal.pdf: 3228826 bytes, checksum: ddfaa133f9f8a9a5a4d1f5233fb205a5 (MD5) / Made available in DSpace on 2016-08-08T12:09:17Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3228826 bytes, checksum: ddfaa133f9f8a9a5a4d1f5233fb205a5 (MD5) Previous issue date: 2016-04-22 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / With the increase of global perspectives regarding renewable energy and the use of concentrated solar thermal energy, with the goal of increasing the flow of solar radiation incident on the thermal has been shown to be a viable solution for electric power generation. The heliostats devices have the ability to track the Sun and reflect the radiation in a pre-set fixed point, usually known as solar tracking Tower in the middle of the field of heliostats devices. The solar towers have been aim of studies because they have a great potential for electric generation. The higher the desired concentration values of the system, the higher the accuracy requirements tracking and reflection of the heliostats, and the quality of reflective surfaces will be. This study aims to design and construction of the heliostat of two degrees of freedom for power generation in solar Tower systems using control methods for tracing and reflection on LabView platform. Applying tracking algorithms based on the solar behavior equations and mechanical design, allowing a two degrees’ freedom dynamic, it was gain results with 0.201 degrees in precision in the tracking of radiation reflection. / Com o aumento das perspectivas mundiais a respeito das energias renováveis e a utilização da energia solar térmica concentrada, com o objetivo de aumentar o fluxo de radiação solar incidente em sistemas térmicos tem se mostrado uma solução viável para geração de energia elétrica. Os dispositivos heliostatos tem a capacidade de rastrear o sol e refletir a radiação em um ponto fixo pré – estabelecido, normalmente conhecido como torre solar localizando se ao meio de um campo de dispositivos heliostatos. As torres solares tem sido alvo de estudos por possuir um grande potencial para geração de energia elétrica. Quanto maior os valores de concentração pretendido do sistema, maiores serão os requisitos de precisão de rastreamento e reflexão do heliostato e da qualidade das superfícies refletoras. Este trabalho tem como objetivo de projeto e construção de um heliostato de dois graus de liberdade para geração de energia em sistemas de torres solares utilizando métodos de controle para rastreamento e reflexão ótima em plataforma LabView. Aplicando algoritmos de rastreamento baseado nas equações de comportamento solar e projeto mecânico permitindo uma dinâmica de dois graus de liberdade foi obtido resultados de 0,201 graus de precisão no rastreamento de reflexão da radiação.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-02-10T11:07:35Z No. of bitstreams: 1 Jair Carlos Muller_.pdf: 2333529 bytes, checksum: 36c56be5b98f22351456fbe4e419d28f (MD5) / Made available in DSpace on 2017-02-10T11:07:35Z (GMT). No. of bitstreams: 1 Jair Carlos Muller_.pdf: 2333529 bytes, checksum: 36c56be5b98f22351456fbe4e419d28f (MD5) Previous issue date: 2016-10-04 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / Este trabalho apresenta um estudo geométrico de um refletor Fresnel linear para a produção de energia térmica com uso de um rastreador solar para orientação dos espelhos. A realização deste trabalho teve como base o estudo do sistema de coordenadas empregado para o cálculo da inclinação dos espelhos em função da posição do Sol em um determinado instante. O método utilizado considera que a radiação direta proveniente do Sol atinja o centro do espelho, cuja inclinação a cada instante permite a reflexão dessa radiação para o centro do absorvedor, situado a uma dada altura em relação ao plano contendo o eixo dos espelhos. Através do estudo da inclinação dos espelhos, foram analisadas as influencias causadas pela distância entre espelhos, altura do receptor, largura dos espelhos e o número de espelhos. Com estes parâmetros analisados, implementou-se uma simulação em MATLAB que forneceu valores de potência refletida no plano de entrada do concentrador secundário, valores de perdas por sombreamento, bloqueio, desfocagem e posição angular de cada fileira de espelho. Tendo estes dados como base foi construído um rastreador solar controlado por um micro controlador Arduino, que permite orientar as fileiras de espelhos com um único motor e eixo de acoplamento. O programa no micro controlador verifica data e hora como dados iniciais, depois as coordenadas geográficas de latitude 29º 45’ 17,979” S e longitude 51º 9’ 1,019” W do local. Assim, foi possível comprovar, através de imagens refletidas pelos espelhos no receptor secundário, que os parâmetros de posição angular estão corretos e que a concentração dos raios solares no absorvedor do concentrador secundário tem precisão adequada, fornecendo ao sistema confiabilidade para sua utilização. / This paper presents a geometric study of a linear Fresnel reflector for the production of thermal energy with use of a solar tracker for orientation of mirrors. This work was based on the study of the coordinate system used for the calculation of the slope of the mirrors as function of the sun’s position at a given time. The method considers that the solar direct radiation reaches the center of the mirror, whose slope at each instant allows the reflection of this radiation to the center of the absorber located at a given height from the plane containing the axis of the mirrors. Through the study of slope of mirrors, were analyzed the influences caused by the distance between mirrors, the height of receiver, width of the mirrors and the number of mirrors. With these parameters, it was implemented a simulation in MATLAB which provided power values reflected in the secondary concentrator inlet plane, values of losses by shading, blocking, by defocus and the angular position of each row of mirror. Having these data as base was built a controlled solar tracker by an Arduino micro controller, which allows directing the rows of mirrors with a single engine and coupling shaft. The program in micro controller checks the date and time as initial data, then the geographical coordinates of latitude 29° 45 ' 17.979 "S and longitude 51° 9 ' 1.019" W the local. Thus, it was possible to prove, through images reflected by mirrors on the secondary receiver, that the angular position parameters are correct and that the concentration of sunrays in the absorber secondary hub has adequate accuracy, providing the system reliability for its use.