Submitted by GUILHERME BIAZZI GONÇALVES null (guibgoncalves.mec@gmail.com) on 2016-03-22T14:34:40Z No. of bitstreams: 1 Dissertação_Guilherme_Goncalves.pdf: 2105715 bytes, checksum: ad6f128191029ac5c1e1ce18a782cf4e (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-23T12:11:07Z (GMT) No. of bitstreams: 1 golcalves_gb_me_bauru.pdf: 2105715 bytes, checksum: ad6f128191029ac5c1e1ce18a782cf4e (MD5) / Made available in DSpace on 2016-03-23T12:11:07Z (GMT). No. of bitstreams: 1 golcalves_gb_me_bauru.pdf: 2105715 bytes, checksum: ad6f128191029ac5c1e1ce18a782cf4e (MD5) Previous issue date: 2016-02-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Nas últimas décadas, o crescente aumento do preço dos combustíveis fósseis associado às crescentes preocupações ambientais têm incentivado as pesquisas sobre o uso de fontes de energia renováveis e os aprimoramentos de seus sistemas e equipamentos. Dentre as fontes alternativas existentes, a energia solar merece ser destacada pelo seu grande potencial de exploração. Os dispositivos solares permitem um amplo espectro de uso, podendo ser utilizados desde operações de grande porte, como hotéis e indústrias, até em sistemas menores típicos de residências. Dentre as aplicações possíveis de energia solar, o sistema de aquecimento de água residencial utilizando coletores solares planos ainda é o mais comum. Este tipo de dispositivo capta a radiação solar por meio de seus coletores e aquece a água que escoa no seu interior e a armazena dentro de um reservatório. Este trabalho propõe estudar uma geometria de coletor alternativa para a captação de energia baseada no coletor de absorção direta. Neste tipo de dispositivo, o fluido de trabalho escoa entre uma placa absorvedora negra e uma placa de vidro e é aquecido indiretamente pela placa absorvedora. Para a avaliação da geometria um modelo numérico bidimensional utilizando o OpenFOAM® foi elaborado. As análises realizadas visaram determinar as condições de contorno ideais para as simulações envolvendo escoamentos de vazão constante e devido ao efeito de termossifão. Com o modelo estabelecido, determinou-se a curva de rendimento da geometria estudada com o intuito de determinar a espessura ideal de fluido que deve escoar dentro do coletor. Pela análise dos resultados obtidos, pode-se concluir que a influência da espessura no rendimento térmico é pequena, sendo que, na faixa avaliada, a espessura de 5,0 mm apresentou os melhores valores de rendimento térmico. / On last decades, the increasing price of fossil fuels associated with the growing concern with the environmental have encouraged researches about renewable energy sources and improvements to its systems and equipment. Among the available alternative sources, solar energy deserves to be highlighted for its great exploitation potential. Solar devices allow a wide range of use, since large operations, such as hotels and industries, to typical smaller residences systems. Among possible applications for solar power, residential water heating systems using flat solar collectors are the most common ones. This type of devices capture solar radiation through their collectors, heat the inside flowing water and stores it in a reservoir. The present work intends to study an alternative collector geometry for energy harvesting based on the direct absorption collector. In this device, the working fluid flows between a black absorber plate and a glass cover and is heated indirectly by the absorber plate. For the geometry evaluation a two-dimensional numeric model was created using OpenFOAM. The analysis aimed to determine the optimal boundary conditions for simulations involving a constant flow and a thermosiphon effect flow. With the model stablished, it was determined the efficiency curve for the geometry in order to find the optimal fluid thickness that flows inside the collector. After the analysis, it can be concluded that the thickness effect on the thermal efficiency is small and, among the evaluated thickness, the 5.00 mm one obtained the best results.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-04-05T20:24:03Z No. of bitstreams: 1 DissGPSae.pdf: 2804979 bytes, checksum: 9f6597a3c56bdce230cda1aefd8057d8 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-19T14:19:34Z (GMT) No. of bitstreams: 1 DissGPSae.pdf: 2804979 bytes, checksum: 9f6597a3c56bdce230cda1aefd8057d8 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-19T14:19:41Z (GMT) No. of bitstreams: 1 DissGPSae.pdf: 2804979 bytes, checksum: 9f6597a3c56bdce230cda1aefd8057d8 (MD5) / Made available in DSpace on 2017-04-19T14:23:55Z (GMT). No. of bitstreams: 1 DissGPSae.pdf: 2804979 bytes, checksum: 9f6597a3c56bdce230cda1aefd8057d8 (MD5) Previous issue date: 2016-08-29 / Não recebi financiamento / The objective of this work is to present the manufacturing parameters of the solar collectors, subject to modification, resulting in improved performance. A discretization of the components of the solar collector was made, identifying the points that could be improved, the importance of each one and its influence on the operation of the collector as a whole. These modifications were simulated by means of a mathematical model, namely: the position of the absorber surface; The distance between the absorber surface and transparent cover; The relationship between thickness and width of the absorber surface. The EES (Engineering Equation Solver) software was used to perform the simulation. The model that was implemented in the EES was a flat solar collector of 1.0 m². After the simulation was carried out, three prototypes were built, one with characteristics common to the collectors available in the market and called the Standard and two more manufactured with the proposed modifications. All the models were sent to the Thermal Efficiency test in a laboratory accredited by INMETRO. The results of the simulation indicated that the change in the position of the absorber surface shows an increase of 0.11 m² in the absorber area of the collector; The computational simulation indicated that the increase in the distance between the absorber surface and the transparent cover in the collectors generated an increase in heat loss from the top of the collector of 0.058 W / m²K; The change of the thickness and width of the absorber surface generated a reduction in the efficiency of 94% in the standard collector to 90% in the proposed prototype. The combination of the mounting position and the distance between the absorber surface and the cover showed a 5% increase in the energy production of this collector. For the results of the laboratory tests it was observed that the prototype with the modifications in the thickness and width of the absorber surface showed a decrease in its performance and the prototype with the combination of the mounting position with the distance between the absorber surface did not show an improvement in its performance , Which was contrary to the mathematical model and whose explanation is due to the uncertainty of ± 2.92% of the production line of the company supplying the prototypes. / O objetivo deste trabalho é apresentar os parâmetros de fabricação dos coletores solares, passíveis de modificação, resultando na melhoria do desempenho. Foi feita uma discretização dos componentes do coletor solar identificando os pontos passíveis de melhoria, a importância de cada um e a sua influência no funcionamento do coletor como um todo. Essas modificações foram simuladas por meio de um modelo matemático, a saber: a posição da superfície absorvedora; a distância entre superfície absorvedora e cobertura transparente; a relação entre espessura e largura da superfície absorvedora. Foi utilizado o software EES (Engineering Equation Solver) para realizar a simulação. O modelo que foi implementado no EES foi um coletor solar plano de 1,0 m². Após a realização da simulação foram construídos três protótipos, sendo um com características comuns aos coletores disponíveis no mercado e chamado de Padrão e mais dois fabricados com as modificações propostas. Todos os modelos foram enviados para ensaio de Eficiência Térmica em laboratório credenciado pelo INMETRO. Os resultados da simulação apontaram que a mudança na posição da superfície absorvedora evidencia um acréscimo de 0,11 m² na área absorvedora do coletor; A simulação computacional indicou que com o aumento na distância entre a superfície absorvedora e a cobertura transparente nos coletores gerou um aumento na perda de calor pelo topo do coletor de 0,058 W/m²K; A troca da espessura e largura da superfície absorvedora gerou uma redução na eficiência de 94% no coletor padrão para 90% no protótipo proposto. A combinação entre a posição de montagem e a distância entre superfície absorvedora e cobertura evidenciou-se um incremento de 5% na produção de energia desse coletor. Para os resultados dos ensaios laboratoriais foi observado que o protótipo com as modificações na espessura e largura da superfície absorvedora apresentou uma queda no seu desempenho e o protótipo com a combinação da posição de montagem com a distância entre superfície absorvedora não apresentou uma melhora no seu desempenho, o que contrariava o modelo matemático e que cuja explicação se deve a incerteza de ±2,92% da linha de produção da empresa fornecedora dos protótipos.

Made available in DSpace on 2014-12-17T14:58:03Z (GMT). No. of bitstreams: 1 DiltonS_DISSERT.pdf: 1329458 bytes, checksum: 93af6e35d0ed131c06c793e3af29ce95 (MD5) Previous issue date: 2010-10-20 / Universidade Federal do Rio Grande do Norte / It was studied a system for heating water to be used to obtain water for bathing at home, the absorbing surface of the collector is formed by one plate of polycarbonate. The polycarbonate plate has 6 mm thick, 1.050 mm wide and 1.500 mm long with an area equal to 1,575 m?. The plate was attached by its edges parallel to PVC tubes of 32 mm. The system worked under the thermo-siphon and was tested for two configurations: plate absorber with and without isolation of EPS of 30 mm thick on the bottom surface in order to minimize heat losses from the bottom. The tank's thermal heating system is alternative and low cost, since it was constructed from a polyethylene reservoir for water storage, with a volume of 200 liters. Will present data on the thermal efficiency, heat loss, water temperature of thermal reservoir at the end of the process simulation and baths. Will be demonstrated the feasibility of thermal, economic and material pickup proposed for the intended purpose. / Estudou-se um sistema para aquecimento de ?gua a ser utilizada para obten??o de ?gua destinada ao banho em resid?ncias, a superf?cie absorvedora do coletor ? formada por uma placa de policarbonato. A placa de policarbonato tem 6 mm de espessura, 1.050 mm de largura e 1.500 mm de comprimento com ?rea correspondente a 1,575 m2. A placa foi ligada pelas extremidades em paralelo a tubos de PVC de ? 32 mm. O sistema funcionou em regime de termo-sif?o e foi testado para duas configura??es: placa absorvedora com e sem isolamento de EPS de 30 mm de espessura na superf?cie inferior para minimizar as perdas t?rmicas pela parte de baixo. O reservat?rio t?rmico do sistema de aquecimento ? alternativo e de baixo custo, pois foi constru?do a partir de um reservat?rio de polietileno para armazenamento de ?gua, com volume de 200 litros. Ser?o apresentados dados de efici?ncia t?rmica, perda t?rmica, temperatura da ?gua do reservat?rio t?rmico no final do processo e de simula??o de banhos. Ser?o demonstradas as viabilidades t?rmica, econ?mica e de materiais do coletor proposto, para o fim desejado

Os sistemas solares de aquecimento de água são uma forma de produção de energia não poluente, que já faz parte da matriz energética brasileira. O uso deste tipo de sistemas traz benefícios econômicos ao país e principalmente a quem os utiliza, devido à poupança no uso de outras fontes de energia para o aquecimento da água. No Brasil o aquecimento solar de água é realizado, principalmente, por coletores solares planos, tecnologia bem conhecida e fabricada no país a preços baixos. Mas atualmente há uma outra tecnologia que está sendo difundida no âmbito nacional, os coletores solares de tubos a vácuo, os quais estão sendo produzidos internacionalmente em uma escala maior, importados e comercializados a preços mais competitivos no mercado nacional. Por isto é necessário entender estes sistemas e o seu funcionamento para evitar erros na sua instalação e otimizar sua operação. Nesta dissertação é realizada uma análise comparativa de um sistema de aquecimento de água composto por um coletor solar de tubos de vidro a vácuo de extração de calor por transferência direta operando em circulação forçada com o mesmo sistema operando em circulação por termossifão. Esta comparação foi realizada determinando a energia anual que o sistema pode produzir para cada tipo de circulação, a qual foi calculada usando como referência a norma ISO 9459-2 e os dados climáticos da cidade de Porto Alegre do Estado do Rio Grande do Sul. Também foram realizadas medições da vazão em termossifão, entre o reservatório e o coletor solar, e foi determinado o coeficiente de perdas térmicas do tanque reservatório segundo os procedimentos da mesma norma. Para isto foi realizada a montagem de uma bancada experimental, com sensores e instrumentos de medida que foram calibrados. Para o sistema de aquecimento testado, os resultados mostram que o sistema trabalhando em circulação por termossifão produz maior quantidade de energia no ano do que o sistema em circulação forçada, onde se observou que a estratificação no tanque reservatório era menor. Também foi observado que a máxima vazão em termossifão para este sistema de aquecimento de água foi de 0,5 L/min. / Solar water heating systems are a method of clean energy production, which is already part of the Brazilian energy matrix. The use of these systems brings economic benefits to the country and especially who use them due to savings in the use of other sources of energy for heating water. In Brazil, the solar water heating is carried out mainly by flat solar collectors, which is a widely known technology because it is produced in the country at low prices. But recently, there is another technology that is being used named: evacuated solar collectors. These collectors are being worldwide produced on a large scale and they are imported and inserted at competitive prices in the domestic market. Therefore it is necessary to understand these systems and their operation to avoid errors in its installation and optimize their operation. In this work, it is accomplishing a comparative analysis of a solar water heating system composed by a water-in-glass evacuated tube solar collector working in forced circulation with the same system working in thermosyphon circulation. This comparison was performed by determining the annual energy that the system can produce for each type of circulation, which was calculated based on the ISO 9459-2 standard and the climatic data of the Porto Alegre city, state of the Rio Grande Do Sul. Also, it was performed thermosyphon measurements between the thermal reservoir and the solar collector, and it was calculated the heat loss coefficient from the reservoir tank according to the procedures of ISO 9459-2 standard. To do so, a testing bench was made, with sensors and measuring instruments which were calibrated before use. For the heating system tested, the results show that the system with thermosyphon circulation produces more annual energy than the forced circulation system where the water temperature stratification in the thermal reservoir was lower. Also, it was observed that the maximum thermosyphon flow for this solar water heating system was 0,5 L/min.

Os sistemas solares de aquecimento de água são uma forma de produção de energia não poluente, que já faz parte da matriz energética brasileira. O uso deste tipo de sistemas traz benefícios econômicos ao país e principalmente a quem os utiliza, devido à poupança no uso de outras fontes de energia para o aquecimento da água. No Brasil o aquecimento solar de água é realizado, principalmente, por coletores solares planos, tecnologia bem conhecida e fabricada no país a preços baixos. Mas atualmente há uma outra tecnologia que está sendo difundida no âmbito nacional, os coletores solares de tubos a vácuo, os quais estão sendo produzidos internacionalmente em uma escala maior, importados e comercializados a preços mais competitivos no mercado nacional. Por isto é necessário entender estes sistemas e o seu funcionamento para evitar erros na sua instalação e otimizar sua operação. Nesta dissertação é realizada uma análise comparativa de um sistema de aquecimento de água composto por um coletor solar de tubos de vidro a vácuo de extração de calor por transferência direta operando em circulação forçada com o mesmo sistema operando em circulação por termossifão. Esta comparação foi realizada determinando a energia anual que o sistema pode produzir para cada tipo de circulação, a qual foi calculada usando como referência a norma ISO 9459-2 e os dados climáticos da cidade de Porto Alegre do Estado do Rio Grande do Sul. Também foram realizadas medições da vazão em termossifão, entre o reservatório e o coletor solar, e foi determinado o coeficiente de perdas térmicas do tanque reservatório segundo os procedimentos da mesma norma. Para isto foi realizada a montagem de uma bancada experimental, com sensores e instrumentos de medida que foram calibrados. Para o sistema de aquecimento testado, os resultados mostram que o sistema trabalhando em circulação por termossifão produz maior quantidade de energia no ano do que o sistema em circulação forçada, onde se observou que a estratificação no tanque reservatório era menor. Também foi observado que a máxima vazão em termossifão para este sistema de aquecimento de água foi de 0,5 L/min. / Solar water heating systems are a method of clean energy production, which is already part of the Brazilian energy matrix. The use of these systems brings economic benefits to the country and especially who use them due to savings in the use of other sources of energy for heating water. In Brazil, the solar water heating is carried out mainly by flat solar collectors, which is a widely known technology because it is produced in the country at low prices. But recently, there is another technology that is being used named: evacuated solar collectors. These collectors are being worldwide produced on a large scale and they are imported and inserted at competitive prices in the domestic market. Therefore it is necessary to understand these systems and their operation to avoid errors in its installation and optimize their operation. In this work, it is accomplishing a comparative analysis of a solar water heating system composed by a water-in-glass evacuated tube solar collector working in forced circulation with the same system working in thermosyphon circulation. This comparison was performed by determining the annual energy that the system can produce for each type of circulation, which was calculated based on the ISO 9459-2 standard and the climatic data of the Porto Alegre city, state of the Rio Grande Do Sul. Also, it was performed thermosyphon measurements between the thermal reservoir and the solar collector, and it was calculated the heat loss coefficient from the reservoir tank according to the procedures of ISO 9459-2 standard. To do so, a testing bench was made, with sensors and measuring instruments which were calibrated before use. For the heating system tested, the results show that the system with thermosyphon circulation produces more annual energy than the forced circulation system where the water temperature stratification in the thermal reservoir was lower. Also, it was observed that the maximum thermosyphon flow for this solar water heating system was 0,5 L/min.

This work addresses the design and real-time implementation of adaptive control strategies on the parabolic solar collector to enhance the production efficiency under varying working conditions. For example, the unpredictable variations of the solar irradiance and thermal losses, these factors can be a major problem in the control design. The control objective is to force the outlet temperature of the collector fluid, to track a predefined reference temperature regardless of the environmental changes. In this work, two control strategies have been designed and analyzed. First, an intelligent proportional-integral feedback control, which combines the proportionalintegral feedback control with an ultra-local model is proposed. This strategy uses a transfer function model that has been derived and identified from real-time data and used to test the controller performance. Second, an adaptive nonlinear control using Lyapunov stability theory combined with the phenomenological representation of the system is introduced. This strategy uses a bilinear model derived from the heat transfer equation. Both control strategies showed good performance in the simulations with respect to the convergence time and tracking accuracy. Besides, the conventional proportional-integral controller has been successfully implemented in the real system.

2015 the Paris agreement was signed to tackle the climate change and reduce emissions from fossil fuel burning. The industrial and manufacturing sector which alone accounts for 32% of global energy use relies heavily on fossil fuels. Solar thermal energy is a renewable energy source that has potential of replacing large portions of this energy. The Swedish research and development company, Absolicon Solar Collectors AB are manufacturers of solar collectors and production lines of dito. Their main product, the Absolicon T160, is a concentrating solar collector which can produce heat up to 160°C.India, and more specifically the state of Gujarat is an interesting market for the solar collectors. This study is aiming to give Absolicon a better understanding of the potential of replacing fossil fuel with solar thermalenergy in Gujarat, so that they can direct their efforts in the right direction. It is a qualitative study mainly focused on the dairy and textile processing industry, two important sectors in the state that has process demands which can be run on solar thermal energy. Since no reliable data regarding the energy consumption in the studied industries where found, a method for estimating the energy consumption is presented in the study.The results from the study shows that large scale manufacturing is possible from a demand point of view, but there are many hindrances for a market penetration. In India large portions of the industry segments studied is non-organized, i.e. small scale with low level of modern technology. Integration of solar thermal energy in the non-organized sector demands a different approach. Based on the results a market analysis with suggestions on how to proceed for the different industrial segments studied is presented.Despite good solar insolation in the state the solar resource was studied in greater detail as aerosols and dust can affect the energy yield from the solar collectors. The results indicates that the annual solar irradiation can be both over- and underestimated when using satellite derived models. India has monsoon seasons and seasonal winds which affects the levels of aerosols in the atmosphere. The level of aerosols and dust has ahigh impact on the solar resource.Ground measurements are therefore a complement that could be used to get a better understandingon site.

Problems of heating of supply water by solar energy are described in this paper. In term of these works was designed and realized attenuate prototype of solar system. There was realized measurements of the temperatures on this prototype and on the basis of these measurements was identified system parameters. Creation of compute simulation of solar system was the further step of this paper. The compute simulation was verified on the basis of comparing of final temperatures with experimental prototype. The design of control algorithm of flow of liquid through the solar system to reach the maximum effect of system is programme of this paper. Simulations of control algorithms are make in environment of MATLAB SIMULINK.

Direct absorption solar collectors offer possible improvement in efficiency over traditional surface absorbing collectors, because they have fewer heat transfer steps and has the ability to utilise higher radiation fluxes. Carbon black based nanofluids, in a base fluid of salt water, were synthesised by a two-step method where the carbon black nanoparticles were treated with a surfactant, TWEEN-20, in a 1:2 mass ratio and sonicated for 60 minutes to break up agglomerates. The synthesised nanofluids showed stability for over 31 days. The different carbon black concentration nanofluids' solar irradiation absorption properties were compared with each other and with the base fluid of salt water in a concentrating, as well as non-concentration scenario. It was found that the carbon black nanofluids showed excellent absorption properties over the entire solar radiation spectrum. A 1 m2 concentrating unit using a two-axis tracking system, with two mirrors and a 1 m diameter circular Fresnel lens, was used to concentrate solar radiation on a direct absorption solar collector flow cell with a 10 cm2 collection area. An optimum concentration of 0.001 volume % carbon black was found to show a 42 % increase in heating rate, compared to that of salt water. The collector was, however, hampered by high energy losses and the maximum collector efficiency achieved was only 46 %, 23 % higher than that of salt water. The overall system efficiency was only 22 %. This low efficiency can be attributed to the high optical concentration losses (50 % - 70 %) present in the concentrating unit. / Dissertation (MEng)--University of Pretoria, 2016. / Chemical Engineering / MEng / Unrestricted

Particulate contamination of the optical surfaces of solar collectors, often called "soiling", can have a significant deteriorating impact on energy yield due to the absorption and scattering of incident light. Soiling has more destructive effect on concentrated solar systems than on flat-plate photovoltaic panels, as the former are incapable of converting scattered sunlight. The first part of this thesis deals with the soiling losses of flat-plate photovoltaic (PV), concentrated solar power (CSP), and concentrated photovoltaic (CPV) systems in operation in several regions of the world. Influential parameters in dust accumulation losses, as well as different cleaning mechanisms in pursuit of restoring the efficiency of soiled systems, have been thoroughly investigated. In lieu of the most commonly-practiced manual cleaning method of using high-pressure water jets, the concept of automatic dust removal using the electrostatic forces of electrodynamic screen (EDS) technology is in a developmental stage and on its way toward commercialization. This thesis provides comprehensive analytical solutions for the electric potential and electric field distribution in EDS devices having different configurations. Numerical simulations developed using finite element analysis (FEA) software have corroborated the analytical solutions which can easily be embedded into software programs for particle trajectory simulations while also providing flexibility and generality in the study on the effect of different parameters of the EDS on the electric field and ensuing dust-removal performance. Evaluation and comparison of different repelling and attracting forces exerted on dust particles is of utmost importance to a detailed analysis of EDS performance in dust removal. Hence, the balance of electrostatic and adhesion forces, including van der Waals and capillary forces, have received significant attention in this dissertation. Furthermore, different numerical analyses have been conducted to investigate the potential causes of observed failures of EDS prototypes that functioned well in a laboratory environment but failed after outdoor exposure. Experimental studies form the last two chapters of this dissertation. Different tests have been conducted on an EDS sample integrated with a PV cell to restore the efficiency of the cell after dust deposition. In order to evaluate the performance of the EDS in dust-particle removal, we have studied the particle size distribution on the EDS surface after each dust deposition and EDS cleaning cycle using a custom-built dust-deposition analyzer. Furthermore, we have pursued several experiments to examine how the geometric and operational EDS parameters affect particle charge via charge-to-mass-ratio measurements.