Load and Season Adapted Solar Collectors

In Sweden solar irradiation and space heating loads are unevenly distributed over the year. Domestic hot water loads may be nearly constant. Test results on solar collector performance are often reported as yearly output of a certain collector at fixed temperatures, e g 25, 50 and 75 C. These data are not suitable for dimensioning of solar systems, because the actual performance of the collector depends heavily on solar fraction and load distribution over the year.At higher latitudes it is difficult to attain high solar fractions for buildings, due to overheating in summer and small marginal output for added collector area. Solar collectors with internal reflectors offer possibilities to evade overheating problems and deliver more energy at seasons when the load is higher. There are methods for estimating the yearly angular irradiation distribution, but there is a lack of methods for describing the load and the storage in such a way as to enable optical design of season and load adapted collectors.This report describes two methods for estimation of solar system performance with relevance for season and load adaption. Results regarding attainable solar fractions as a function of collector features, load profiles, load levels and storage characteristics are reported. The first method uses monthly collector output data at fixed temperatures from the simulation program MINSUN for estimating solar fractions for different load profiles and load levels. The load level is defined as estimated yearly collector output at constant collector temperature divided be yearly load. This table may examplify the results:CollectorLoadLoadSolar Improvementtypeprofile levelfractionover flat plateFlat plateDHW 75 %59 %Load adaptedDHW 75 %66 %12 %Flat plateSpace heating 50 %22 %Load adaptedSpace heating 50 %28 %29 %The second method utilises simulations with one-hour timesteps for collectors connected to a simplified storage and a variable load. Collector output, optical and thermal losses, heat overproduction, load level and storage temperature are presented as functions of solar incidence angles. These data are suitable for optical design of load adapted solar collectors. Results for a Stockholm location indicate that a solar combisystem with a solar fraction around 30 % should have collectors that reduce heat production at solar heights above 30 degrees and have optimum efficiency for solar heights between 8 and 30 degrees.

Perspectivas de inserção da energia solar fotovoltaica na geração de energia elétrica no Rio Grande do Norte

The generation of electricity in Brazil is predominantly renewable, with internal hydraulic generation being more than 70% of its energy matrix. The electricity rationing occurred in 2001 due to lack of rain, led the country to increase the participation of alternative energy sources. This need for new sources of energy makes the regional potential to be exploited, which configures the change of generation model from centralized generation to distributed generation. Among the alternative sources of energy, the solar energy is presented as very promising for Brazil, given that most of its territory is located near to the equator line, which implies days with greater number of hours of solar radiation. The state of Rio Grande do Norte (RN) has one of the highest levels of solar irradiation of the Brazilian territory, making it eligible to receive investments for the installation of photovoltaic solar plants. This thesis will present the state-of-the-art in solar photovoltaic power generation and will examine the potential for generation of solar photovoltaic power in Brazil and RN, based on solarimetrics measurements conducted by various institutions and also measurements performed in Natal, the state capital

Viabilidades térmica, econômica e de materiais de um sistema solar de aquecimento de água a baixo custo para fins residenciais

An solar alternative system for water heating is presented. Is composed for one low cost alternative collector and alternative thermal reservoir for hot water storing. The collector of the system has box confectioned in composite material and use absorption coils formed for PVC tubes. The box of hot water storage was confectioned from a plastic polyethylene drum used for storage of water and garbage, coated for a cylinder confectioned in fiber glass. The principle of functioning of the system is the same of the conventionally. Its regimen of work is the thermosiphon for a volume of 250 liters water. The main characteristic of the system in considered study is its low cost, allowing a bigger socialization of the use of solar energy. It will be demonstrated the viabilities thermal, economic and of materials of the system of considered heating, and its competitiveness in relation to the available collectors commercially. Relative aspects will be boarded also the susceptibility the thermal degradation and for UV for the PVC tubes. It will be shown that such system of alternative heating, that has as main characteristic its low cost, presents viabilities thermal, economic and of materials

Análise da viabilidade econômica de um sistema de aquecimento solar de água para uma empresa do setor hoteleiro

This paper presents an analysis of technical and financial feasibility of the use of a solar system for water heating in a fictitious hotel located in the Northeast region. Thereunto it is used techniques of solar collectors´ sizing and methods of financial mathematics, such as Net Present Value (NPV), Internal Rate of Return (IRR) and Payback. It will also be presented a sensitivity analysis to verify which are the factors that impact the viability of the solar heating. Comparative analysis will be used concerning three cities of distinct regions of Brazil: Curitiba, Belém and João Pessoa. The viability of using a solar heating system will be demonstrated to the whole Brazil, especially to the northeast region as it is the most viable for such an application of solar power because of its high levels of solar radiation. Among the cities examined for a future installation of solar heating systems for water heating in the hotel chain, João Pessoa was the one that has proved more viable.

Estudo de um sistema híbrido de destilação solar para polimento de águas produzidas

The oil industry, experiencing a great economic and environmental impact, has increasingly invested in researches aiming a more satisfactory treatment of its largest effluent, i.e., produced water. These are mostly discarded at sea, without reuse and after a basic treatment. Such effluent contains a range of organic compounds with high toxicity and are difficult to remove, such as polycyclic aromatic hydrocarbons, salts, heavy metals, etc.. The main objective of this work was to study the solar distillation of produced water pre-treated to remove salts and other contaminants trough of a hybrid system with a pre-heater. This developed apparatus was called solar system, which consists of a solar heater and a conventional distillation solar still. The first device consisted of a water tank, a solar flat plate collector and a thermal reservoir. The solar distillator is of simple effect, with 1m2 of flat area and 20° of inclination. This dissertation was divided in five steps: measurements in the solar system, i.e. temperatures and distillate flow rate and weather data; modeling and simulation of the system; study of vapor-liquid equilibrium of the synthetic wastewater by the aqueous solution of p-xylene; physical and chemical analyses of samples of the feed, distillate and residue, as well as climatology pertinent variables of Natal-RN. The solar system was tested separately, with the supply water, aqueous NaCl and synthetic oil produced water. Temperature measurements were taken every minute of the thermal reservoir, water tank and distillator (liquid and vapor phases). Data of solar radiation and rainfall were obtained from INPE (National Institute for Space Research). The solar pre-heater demonstrated to be effective for the liquid systems tested. The reservoir fluid had an average temperature of 58°C, which enabled the feed to be pre-heated in the distillator. The temperature profile in the solar distillator showed a similar behavior to daily solar radiation, with temperatures near 70°C. The distillation had an average yield of 2.4 L /day, i.e., an efficiency of 27.2%. Mathematical modeling aided the identification of the most important variables and parameters in the solar system. The study of the vapor-liquid equilibrium from Total Organic Carbon (TOC) analysis indicated heteroazeotropia and the vapor phase resulted more concentrated in p-xylene. The physical-chemical analysis of pH, conductivity, Total Dissolved Solids (TDS), chlorides, cations (including heavy metals) and anions, the effluent distillate showed satisfactory results, which presents a potential for reuse. The climatological study indicates the region of Natal-RN as favorable to the operation of solar systems, but the use of auxiliary heating during periods of higher rainfall and cloud cover is also recommended

Sistema de geração fotovoltaico multifuncional

Pós-graduação em Engenharia Elétrica - FEB

Desinfecção da água utilizando aquecimento solar

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Avaliação do desempenho hidro-energético de sistemas fotovoltaicos utilizados no bombeamento de água

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Desempenho de um sistema híbrido eólico-fotovoltaico de pequeno porte para energização rural

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Adoção da energia solar fotovoltaica em hospitais: revisando a literatura e algumas experiências internacionais

The sun has an extremely important role in the existence of human beings, and Brazil has a privileged geographical position to explore sunlight. The union of these two factors favors the use of solar cells for converting solar energy into electricity by photovoltaic technology: it is a great alternative energy source, especially for being a clean one, causing less damage to the environment. This paper addresses the photovoltaic technology with a focus on hospitals, through case studies found in international literature, because hospitals, even running all important services to society, have a potential for pollution capable of causing damage to human health and the environment that is around them. It is estimated that the Brazilian oil reserves are sufficient for twenty-two years. This makes the search for alternative sources for power generation a necessity.

A ring system detected around the Centaur (10199) Chariklo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The evolution of a Pluto-like system during the migration of the ice giants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sistema fotovoltaico monocristalino para bombeamento de água

Since ancient times, it has been a huge challenge to all people around the world to manage to get their fresh water, keeping it clean and providing it to every human being, so that it can be used for their daily needs. This is especially true for small properties in the countryside and in isolated areas with low demographic density. Pumping the water in those regions is a solution that rationalizes its use in domestic chores, in animal rearing and in the irrigation systems of cultivated areas. Making feasible local, renewable and non-polluted energetic alternatives is the aim for those areas that are usually far away from the public electric network. Using photovoltaic solar energy is the alternative now proposed. For this objective was built a system with two monocrystalline panels, one pump, two water tanks, two level sensors and a solenoid valve to pump water, using a pump powered an array of monocrystalline solar panels. The main goal was to compare their rate of water flow and their energy consumption. The use of one data acquisition equipment allowed collecting meteorological, electrical and hydraulic values, and also serving for the control and activation of the pumping system. During four months in a row as from April 2009, arrangements with one or two panels were tested. Mathematics correlations and adjustment lines were used to interpret the behavior of obtained dataset. During the analyzed period the system followed the linear equations with great accuracy. The daily average amount of water pumped by the several tested arrays stayed between 1,100 and 2,500 liters, and that is enough to supply a small rural property. The pumping system with two panels effectively showed the major amount of water, but a system with one panel can be an economical solution until 1,500 liters on day. It did not characterize a direct relationship between power or quantity of photovoltaic panels and daily outflow of water pumping.

Utilização de painéis solares fotovoltaicos no segmento residencial

In order to diversify the global and national energy matrix and reduce harmful impacts on the environment caused by the emission of polluting gases into the atmosphere, the use of clean and renewable energy sources is presented as a good alternative. This work discusses the use of photovoltaic solar energy, a source that presents such characteristics. The photovoltaic system under study is the type distributed connected to the grid, in the residential segment. It is informed of its use in the global and national levels. They are also present their characteristics, electrical and electronic circuits that make up the equipment required for its operation and the design of a system to be installed in a residence

Utilização de painéis solares fotovoltaicos no segmento residencial

In order to diversify the global and national energy matrix and reduce harmful impacts on the environment caused by the emission of polluting gases into the atmosphere, the use of clean and renewable energy sources is presented as a good alternative. This work discusses the use of photovoltaic solar energy, a source that presents such characteristics. The photovoltaic system under study is the type distributed connected to the grid, in the residential segment. It is informed of its use in the global and national levels. They are also present their characteristics, electrical and electronic circuits that make up the equipment required for its operation and the design of a system to be installed in a residence