Made available in DSpace on 2014-06-12T23:17:10Z (GMT). No. of bitstreams: 2 arquivo9133_1.pdf: 4158769 bytes, checksum: 8d5fc238bddec95df999443c11d7f090 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2007 / Este trabalho apresenta o desenvolvimento, princípio de funcionamento e a avaliação experimental de sistema de controle de um rastreador solar. Um gerador fotovoltaico (FV) tem o máximo aproveitamento quando a normal da sua superfície aponta para o Sol. A função de um rastreador solar é fazer com que isso aconteça com precisão adequada para o gerador FV. O sistema de controle desenvolvido promove o rastreio do Sol ao longo do dia, com retorno ao fim do dia promovido por um banco de baterias. O sistema foi testado durante vários dias. Verificou-se que o sistema de controle promove o rastreio do Sol com boa precisão (erro máximo de 3 graus para céu claro) e possibilita um ganho significativo (até 42,9%) na energia solar coletada em comparação a sistemas FV fixos. O sistema de controle, construído com componentes facilmente encontrados no mercado local, mostrou-se confiável, além de apresentar custo de um terço do similar importado e fácil manutenção

A new technique for detecting solar oscillations in the visible to near infrared continuum has been developed and tested at the Santa Catalina Laboratory for Experimental Relativity by Astrometry (SCLERA). In 1985, measurements of the solar radiation intensity near disk center were made by Oglesby (1986, 1987). The results of these observations have been compared to the reported detections and classifications by Hill (1984, 1985) and Rabaey and Hill (1987) of the low-order, low-degree acoustic modes; the intermediate degree f-modes; and the low-order g-modes. For the low-order, low-degree, acoustic modes and the intermediate degree f-modes, a total of 40 multiplets were used in the analysis. The coincidence rates between the peaks in the power spectrum of the 1985 observations and the classified frequency spectrum for multiplets taken in subgroups of ≈5 (same n and contiguous in ℓ) are typically 4-5 σ above the accidental coincidence rate. The maximum coincidence rates for these same subgroups of multiplets were found to occur for frequency shifts of the classified spectrum ranging from -0.27 μHz for modes that are sensitive to the internal properties near the bottom of the convection zone to 0.06 μHz for modes that are sensitive to internal properties near the top of the convection zone. Also included in this work is a comparison of diameter measurements obtained at SCLERA in 1978 (Caudell 1980) with the classified modes mentioned above. Agreement in this case is at the 3.1 σ level for both the f-mode (n = 0) multiplets with 21 ≤ ℓ ≤ 36 and the n = 1, 6 ≤ ℓ ≤ 12 acoustic modes. The confirmation of the detection and classification of the low-order g-modes of oscillation was found to be at the 3.3 σ level. Additionally, the m dependence of the 1985 power spectrum was found to behave in the manner expected for the proper classifications in m for the g-modes.

Nowadays Solar Energy is one of the engineering fields most exploited, due to the ongoing need to developing new technologies based on renewable energy or improving the existing ones. One particular application of this kind of energy is Solar Cooling, which consist in generating cold from the heat received from the Sun. A common installation of solar cooling requires solar collectors, an absorption/adsorption chiller, fan coils, piping, valves and pumps. It calls for a minimal preventive maintenance which should allow keeping operating conditions within certain limits.The aim of this work is to analyze the viability of the installation of a solar cooling system in a roof. It has been chosen the Building 45 of the University of Gävle (Hus 45) as a pattern design. It was built in 2008, thirteen years after Högskolan i Gävle was inaugurated. This building uses electric compression coolers for its cooling demand. According to their heating demand, this is solved by using District Heating.This work is focused on the determination of the cooling demand of this particular building and the proposal of a solar cooling system that could supply it. Calculating the cooling demand means applying most of the concepts learnt during the whole speciality of the degree, like thermal loads in buildings. This calculation has been possible by using IDA ICE, which is a software that allows the user to develop a new construction through defining all structure parameters. After having defined all the contour conditions, the simulation shows all kinds of parameters in detail, in particular, the cooling demand of the respective building. Moreover, creating a new solar cooling system for this building means reviewing all the concepts related to refrigeration cycles and solar energy that have been learnt during the intensification. To do it, it has been necessary to use POLYSUN, another program that let the user to create solar thermal systems, photovoltaic systems or any other installation for getting heating, cooling or hot water.In addition, another important point to discuss is the usage of a solar cooling system based on absorption/adsorption technology instead of using photovoltaic as a way of providing to the current cooling units.The simulation about the cooling demand of the building shows that for covering the 95,22% of the operation hours (within the study), it is required to solve a cooling peak demand of 100 kW, which is in terms of energy a value of 68437,6 kWh. Regarding the designs of the solar cooling systems, two variants have been analyzed. While the first one is based on using the absorption technology, the second one has two subdivided proposals: a stand-alone photovoltaic system and a net metering installation. The absorption system could cover the cooling demand with the exception of July. The viability of this installation is questioned because of the low operation hours of the absorption machine, which is not working as it was expected since it is the cooling tower who really carries out the cooling function. On the other hand, the stand-alone system allows the building to cover all of its cooling demand, but the system is oversized and no profitable within a period of 30 years although it supposes a reduction of 100% in CO2 emissions, which is obvious since this option considers an electrical consumption from the grid of 0 kWh. Finally, the net metering system is probably the best option for covering the cooling demand of this building, as it has the shorter pay-back (18 years), the less visual impact when the solar modules are installed on the roof and requires less maintenance.Since there are no advantages in using an absorption machine for a cooling system in a Swedish climate, the next step would be analysing a system like the one proposed into another climate, where the solar radiation has more influence, thus, the absorption machine could work because of the inlet water (coming from the solar loop) is hot enough.

Uma simulação numérica do ciclo de refrigeração a adsorção é realizada para os pares zeólita-água e carvão ativo AC-35 metanol, justificando a escolha do par bem como do sistema de captação a serem utilizados no protótipo. O protótipo construído compreende um concentrador cilíndrico-parabólico com rastreamento solar, um tubo de calor e uma unidade frigorífica (com zeólita-água). Aspectos tecnológicos como válvulas, soldas e carregamento do par na máquina são analisados. Os resultados dos testes de desempenho são apresentados, discutidos e comparados com a literatura. Uma análise de custos é feita. Paralelamente, construímos termo pilhas pelo método da evaporação. Estas termopilhas foram utilizadas na construção do piranômetro e do pireliômetro. Os instrumentos são caracterizados em termos de sensibilidade, constante de tempo, linearidade, efeitos de temperatura e convecção natural. Os resultados desta caracterização são discutidos e comparados com um modelo fabricado pela Eppley. Finalmente, no apêndice I, testamos o desempenho de um coletor plano utilizando no absorvedor o revestimento seletivo de óxido de alumínio recentemente desenvolvido no IFQSC. As melhores condições para obtenção do revestimento seletivo em placas de grande porte são estudadas. / A numerical simulation of the adsorption refrigeration cycle was made for zeolite/water and activated carbon(AC-35)/ methanol pairs, to select the pair and the solar collector in the prototype. The fabricated prototype consists of a cylindrical paraolic concentrator with solar trackins, a heat pipe and the refrigeration unit (with the zeolite/water pair). The technical aspects of values, welds and out-gassing are analyzed. The results of the performance tests are presented, discussed and compared with the literature. An analysis of costs is made. In parallel thermopiles were constructed using the evaporation method. These thermopiles were used in the construction of the piranometer and the pirheliometer. The instruments were characterized in terms of: sensitivity, stability with time, linearity, effects of temperature and natural convenction. The results of this characterization are discussed and compared with a model made by Eppley. Finally, in Apendix I, we tested the performance of a flat plate collector using a selective coating of aluminium oxide (developed in IFQSC) as absorber. The Best conditions for obtaining the seletive coating on big size plates are discussed.

MINP solar cells ; Hoi Chi-sam. / Includes bibliographical references / Thesis (M.Phil.)--Chinese University of Hong Kong, 1983

by Poon Ming-cheong. / Bibliography: leaves 97-102 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1983

Graduation date: 1968

Solar radiation intensities, incident to the sea surface off the Oregon coast, are measured and compared. Simplification of some physical and biological problems can be anticipated if the average radiation received over a broad segment of ocean can be accurately indicated by the amount recorded at the land station. The area of ocean over which the study was made extends the length of the Oregon coast and 165 miles to sea. The measurements were made during the months of June, July, August, and September 1963 with an Eppley total radiation pyrheliometer. A division of the study area into Newport and three zones parallel to the coast separated the data into comparative groups. Clear sky radiation values, assumed constant with longitude, are used as bases for comparison. For each value of observed radiation, a corresponding clear sky value was calculated using standard techniques. Curves, based on a dust-free atmosphere with two cm of precipitable water, are developed to provide these calculated values. Before the recorded values from the zones are compared, their corresponding calculated spectra are adjusted to be identical. This is done by weighting the number of observations in each classification. In all instances, the zone values are adjusted to those of Newport. Comparison is made between mean intensity values, percentages of calculated clear sky values, relative and cumulative frequencies of intensities, and composites of daily traces. Two methods of analysis are employed. One classifies data by intensity level, and the other classifies it by the hour of the day during which it was recorded. Not enough observations were available in the two zones farthest from Newport to provide smooth curves. It is found, however, that there is essentially no change with longitude in observed intensity spectra and means. It is concluded that the average radiation recorded at Newport indicates with some accuracy the average radiation received over the section of ocean in question. / Graduation date: 1965

The work presented in this thesis concerns the dimensioning of an Energy Storage System (ESS) which will be used as an energy buffer for a grid-connected PV plant. This ESS should help managing the PV plant to inject electricity into the grid according to the requirements of the grid System Operator. It is desired to obtain a final production not below 1300kWh/kWp with a maximum ESS budget of 0.9€/Wp. The PV plant will be sited in Martinique Island and connected to the main grid. This grid is a small one where the perturbations due clouds in the PV generation are not negligible anymore. A software simulation tool, incorporating a model for the PV-plant production, the ESS and the required injection pattern of electricity into the grid has been developed in MS Excel. This tool has been used to optimize the relevant parameters defining the ESS so that the feed-in of electricity into the grid can be controlled to fulfill the conditions given by the System Operator. The inputs used for this simulation tool are, besides the conditions given by the System Operator on the allowed injection pattern, the production data from a similar PV-plant in a close-by location, and variables for defining the ESS. The PV production data used is from a site with similar climate and weather conditions as for the site on the Martinique Island and hence gives information on the short term insolation variations as well as expected annual electricity production. The ESS capacity and the injected electric energy will be the main figures to compare while doing an economic study of the whole plant. Hence, the Net Present Value, Benefit to Cost method and Pay-back period studies are carried on as dependent of the ESS capacity. The conclusion of this work is that it is possible to obtain the requested injection pattern by using an ESS. The design of the ESS can be made within an acceptable budget. The capacity of ESS to link with the PV system depends on the priorities of the final output characteristics, and it also depends on which economic parameter that is chosen as a priority.

In this work, we studied the blends of metallic nanoparticle and polymers as a donor/acceptor bulk heterojunction active layer. The mobility of the free charge carriers in thin polymer films is lower, so we blended Pd nanoparticles (Pd NPs) into polymers to improve carrier mobility, and enhance the power conversion efficiency of the polymer solar cell. P3HT was used as a donor material because of its high stability and with high absorption in visible light. PCBM was used as a acceptor material because of its high stability and with high electron transportation. We blended nanoparticles that include different size (5nm and 20nm) and different metal (Pd and Pt) and blended into the P3HT:PCBM active layer, with the device configurations of ITO/PEDOT:PSS/P3HT:PCBM: Pt NPs/Al. Polymer solar cells measured was under AM 1.5G 100mW/cm2 illumination. When we blended Pd NPs and Pt NPs into the active layer, the power conversion efficiency increased from 2.43% to 2.78%. We will study dispersion and characteristic of different size nanoparticles in the active layer.