Optical Characterization Parameters for Line-focusing Solar Concentrators: Measurement Procedures and Extended Simulation Results

According to the present standards, the optical characterization of line-focusing concentrators follows the quasi-dynamic test method, thus resulting from thermally based experimental measurements. The impact of optical deviations from design conditions on a concentrator optical performance increases with concentration ratio. Adding to this, the geometrical specificities which might be found in line-focus concentrators render important a more thorough optical characterization of such systems. The present article studies the interest and possibility of using optical simulation data as a complement to the experimental procedures followed in the optical characterization of line-focusing concentrators. Taking into account the isolated and combined impact of the most prominent optical effects in presence, the validation and accuracy of optical models is compared to that of experimental measurements. Additional optical characterization results to be obtained from such models are suggested, complementing the optical parameters previewed in the standards and enabling a higher accuracy in yield calculations

Projeto SHIP

Solar heat for industrial processes (SHIP) has presented itself as a worldwide solar thermal niche market where at least 741 systems, with 662 648 m2 of collectors area (567 MWth), could be found at the end of 2018 in operation, 108 of which were new systems that started its operation in that year. In Portugal, besides small scale and low temperature particular cases, mainly towards domestic hot water production, solar process heat is virtually non-existent. The SHIP project – Solar Heat for Industrial Processes (P2020) – had as its main goal to develop and demonstrate, at the company KEMET Electronics Portugal S.A., in Évora, a direct integration of medium temperature solar thermal technology system, testing and validating it, assuring in this way its proximity/readiness to the market

Calor de processo solar: competitividade e necessidade de modelos de financiamento

Excluding the non-energetic uses of primary energy sources, process heat related Final Energy Consumption (FEC) stands, worldwide, to 23% of the total FEC (among all sectors). Presenting the potential to supply industry with low and medium temperature heat demands – 52% of the overall heat demand in industry – solar process heat market penetration is marginal, standing for about 0,1% of the total installed capacity of solar thermal energy. With many of the technical and technological questions which could impair he adoption of solar thermal technologies in industrial applications, this weak market penetration is mostly due to economic competitiveness reasons. The present article assesses the critical boundary conditions for the competitiveness of solar process heat. Based in different technology, conventional energy sources and emission cost scenarios, this assessment presents the impact of different business models in the competitiveness of this technological option

Determinação de substância dérmica da pele

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Development and Test Results of a Calorimetric Technique for Solar Thermal Testing Loops, Enabling Mass Flow and Cp Measurements Independent from Fluid Properties of the HTF Used

Thermal heat transfer fluids (HTF) used in solar collectors (e.g. synthetic oils) are known to age and degrade [1]. This degradation is impossible to control, affecting the fluid heat transfer capacity and thus the ability of measuring the performance of an HTF heating device (e.g. a solar collector) based on known specific heat values. Collector testing is also crucially dependent on an accurate measurement of HTF mass flow rate. Such measurement relies on flow meters suitable for the accuracy, operating temperature and flow range requirements of the testing procedures, often an expensive and demanding component in particular when no-intrusive measurements are to be done ia a close circuit. For power measurement purposes, as those performed in solar collector testing procedures, a direct measurement of the product between specific heat and mass flow rather than a separate measurement of both quantities is suitable. A calorimetric technique delivering this direct measurement is thus a suitable strategy to overcome such difficulties with acceptable (and even higher) measurement accuracy. Solutions of this kind have already been proposed [2,3]. In this paper we revisit and improve the solution presented in [2] and demonstrate its usefulness in a solar collector testing loop, for temperatures up to 200 °C. A calorimeter prototype was thoroughly tested and calibrated with water as HTF (enabling accurate independent measurement of specific heat and mass flow rates values). Calorimeter calibration results where then used in the testing with thermal oil whose specific heat values were previously known from manufacturer and independent laboratory measurements. A comparison of Cp measured by the calorimeter with the value given by the HTF manufacturer is used to test the calorimeter capacities. The agreement achieved was very good. It is noted that the technique can be easily implemented in any high temperature loops, large or small

Atitudes dos alunos face à disciplina de Educação Física : influência das variáveis género, nível socioeconómico e nota da disciplina

Relatório de estágio de Mestrado em Ensino de Educação Física nos Ensinos Básico e SecundárioO presente relatório retrata as atividades pedagógicas do estagiário de Educação Física durante o ano letivo, tendo o estágio assumindo-se o momento ideal para uma aprendizagem orientada e profundamente reflexiva. Este documento aborda o enquadramento contextual, a intervenção pedagógica no processo ensino-aprendizagem, a participação na escola e a relação com a comunidade educativa. Em cada uma destas áreas procuramos contextualizar as tomadas de decisão e as opções didático-metodológicas adotadas, identificando as dificuldades e as estratégias definidas para as ultrapassar. Este relatório integra uma vertente investigativa, indissociável da interpretação e avaliação da intervenção pedagógica desenvolvida ao longo do ano letivo. São vários os estudos que evidenciam a importância de ter uma atitude favorável face à disciplina de educação física, sendo esta capaz de potenciar as aprendizagens, influenciar a participação futura dos jovens em atividades físicas e consequentemente a adoção de um estilo de vida ativo. O objetivo deste estudo foi analisar as atitudes dos alunos face à disciplina de educação física e verificar as diferenças das atitudes dos alunos em função da variável género, nível socioeconómico, e nota da disciplina. A amostra é constituída por 85 estudantes (47 rapazes e 38 meninas) do 9º e 10º ano de escolaridade, cujas idades variavam entre os 14 e 16 anos. Os resultados mostraram que os alunos evidenciam, de modo geral, uma atitude positiva face à disciplina, gostam e consideram-na importante na sua formação. Analisando a influência das diferentes variáveis, verificamos a existência de relações estatisticamente significativas entre o género, a nota final e as diferentes dimensões das atitudes. O nível socioeconómico não influencia as atitudes dos alunos face à disciplina de educação física.This report reflects the activities of the trainee teaching physical education during the school year, taking the stage assuming the ideal time for a learning-oriented and deeply reflective. This document addresses the contextual framework, the educational intervention in teaching-learning process, participation in school and community relations education. In each of these areas seek to contextualize the decision making and didacticmethodological options adopted, identifying the difficulties and strategies defined to overcome. This report includes an investigative strand, inseparable from the interpretation and assessment of educational intervention developed throughout the school year. There are several studies that show the importance of having a favorable attitude to the discipline of physical education, which is able to enhance the learning, influence the future participation of young people in physical activity and consequently the adoption of an active lifestyle. The aim of this study was to analyze the attitudes of students in the face of physical education classes and check the differences of students' attitudes depending on the variable gender, socioeconomic status, and note the discipline. The sample consisted of 85 (47 boys and 38 girls) from the 9th and 10th grade, and aged between 14 and 16 years. The results showed that students demonstrate, in general, a positive attitude to discipline, love and consider it important in its formation. Analyzing the influence of the different variables, we verify the existence of statistically significant relationships between gender, the final grade and the different dimensions of attitudes. The socioeconomic status does not influence the attitudes of students face the discipline of physical education

Modelagem de controladores PID utilizando o simulador EMSO

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Análise da temperatura de retração do couro

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Calor de processo solar: competitividade e necessidade de modelos de financiamento

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMO: Excluídos os usos não energéticos de fontes de energia primária, os consumos de energia final (FEC) associados à produção de calor de processo no sector Industrial correspondem, à escala global, a 23% do FEC total entre todos os sectores. Apresentando o potencial de suprir as necessidades de calor de processo a baixa e média temperatura – 52% das necessidades – a sua penetração actual no mercado corresponde, à escala global, a cerca de 0,1% da capacidade total instalada em energia solar térmica. Resolvidas que estão muitas das questões técnicas e tecnológicas que poderiam apresentar-se como limitações à adopção destas tecnologias pela indústria, esta fraca penetração deve-se, sobretudo, a questões de competitividade económica. O presente artigo analisa as condições de fronteira críticas para a competitividade do calor de processo solar, tendo por base cenários de evolução de custos da tecnologia, fontes de energia primária e valorização de emissões evitadas. Nesta análise é avaliado o impacto de diferentes modelos de negócio na competitividade desta solução.ABSTRACT: Excluding the non-energetic uses of primary energy sources, process heat related Final Energy Consumption (FEC) stands, worldwide, to 23% of the total FEC (among all sectors). Presenting the potential to supply industry with low and medium temperature heat demands – 52% of the overall heat demand in industry – solar process heat market penetration is marginal, standing for about 0,1% of the total installed capacity of solar thermal energy. With many of the technical and technological questions which could impair he adoption of solar thermal technologies in industrial applications, this weak market penetration is mostly due to economic competitiveness reasons. The present article assesses the critical boundary conditions for the competitiveness of solar process heat. Based in different technology, conventional energy sources and emission cost scenarios, this assessment presents the impact of different business models in the competitiveness of this technological option.info:eu-repo/semantics/publishedVersio

Modelagem numérica da estraficação térmica vertical de reservatórios

Orientador : Prof. Dr. Maurício Felga GobbiDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Ambiental. Defesa: Curitiba, 2014Inclui referências : f. 95-97Resumo: O presente trabalho trata do estudo de estratificação térmica em reservatórios. O ciclo de estratificação térmica é suposto ser influenciado principalmente pelas condições meteorológicas. Assim, os processos de troca de calor que ocorrem na interface ar-água como a radiação solar incidente de onda curta, a radiação atmosférica incidente de onda longa, a radiação emitida pela superfície da água, a perda de energia por evaporação e a perda ou ganho de energia por calor sensível são considerados os principais processos que alteram o regime térmico do reservatório. As fontes de calor laterais e o fluxo de calor no fundo são consideradas desprezíveis. O conceito de temperatura de equilíbrio e de coeficiente de troca de calor são utilizados para estimar o fluxo de energia total que ocorre na interface ar-água. Para resolver a distribuição de temperatura ao longo da coluna d'água, um modelo matemático é desenvolvido no qual utiliza-se a equação da transferência de calor unidimensional. A equação da transferência de calor é resolvida numericamente pelo Método de Diferenças Finitas, esquema de Cranck-Nicolson. O coeficiente de difusão turbulenta é parametrizado em relação à velocidade do vento e gradientes estáveis ou neutros de temperatura na coluna d'água. Após alguns estudos de casos simplificados do modelo proposto (Caso 1 a 3), o modelo é aplicado para descrever o ciclo de estratificação térmica do Reservatório do Rio Verde localizado na região metropolitana de Curitiba-PR, Brasil, entre junho de 2009 e dezembro de 2010 (Caso 4 e 5). Caso 4: Entre o ano de 2009 e 2010, os resultados de temperatura de equilíbrio estimados apresentaram os maiores valores no período de estudo e proporcionaram situações de forte estratificação do reservatório. De abril a setembro de 2010, os perfis de temperatura medidos mostraram um reservatório praticamente isotermal e os resultados obtidos pelo modelo apresentaram boa concordância nesse período. A partir de setembro de 2010, os perfis de temperatura medidos mostram uma situação de forte estratificação, porém, o modelo não foi capaz de reproduzir tal situação devido aos baixos valores de temperatura de equilíbrio estimados. A defasagem entre a temperatura de equilíbrio e a temperatura da superfície da água apenas foi possível assumindo um coeficiente de troca de calor constante. Caso 5: Utilizando um coeficiente de troca de calor estimado a partir de uma expressão analítica, os resultados mostraram que a temperatura da superfície da água e a temperatura de equilíbrio estavam em fase e apresentou valores próximos. O Caso 5 apresentou melhor concordância com os dados comparado ao Caso 4. Embora, em algumas situações o modelo não tenha reproduzido a forte estratificação observada, a proposta que o regime térmico do Reservatório do Rio Verde é influenciado pelas condições meteorológicas mostrou-se bastante satisfatória. Palavras-chaves: Estratificação térmica de corpos d'água. Equação da transferência de calor unidimensional. Temperatura de equilíbrio.Abstract: The present work refers to the study of thermal stratification in reservoirs. The cycle of thermal stratification is supposed to be mainly influenced by the meteorological conditions, including solar radiation, air temperature, relative humidity and wind speed which are the external forcing that alter the thermal regime of the reservoir. Thus, the processes of heat exchange that occur at the air-water interface as the short-wave solar radiation, the longwave atmospheric radiation, the long-wave radiation emitted from the water surface, the energy loss by evaporation and the loss or gain energy by heat conduction are considered the main processes that alter the thermal regime. The sources of lateral heat and the heat flux at the bottom are considered negligible. The concept of equilibrium temperature and heat transfer coefficient are used to estimate the total energy budget that occurs at the air-water interface. To resolve the temperature distribution throughout the water column, a mathematical model is developed in which the equation of one-dimensional heat transfer was used. The equation of heat transfer is numerically solved by the Method of Finite Differences, Crank-Nicolson scheme. The coefficient of turbulent diffusion is parameterized in relation to the wind speed and stable temperature gradients in the water column. After some studies of simplified cases of the proposed model (Case 1 to 3), the model is applied to describe the cycle of thermal stratification of Rio Verde Reservoir located in the metropolitan region of Curitiba-PR, Brazil, between June 2009 and December 2010 (Case 4 and 5). Case 4: Between 2009 and 2010, the results of the estimated equilibrium temperature showed the highest values during the study period and provided situations of strong stratification of the reservoir. From April to September 2010, the measured temperature profiles showed a nearly isothermal reservoir and the results obtained by the model showed good conformity in this period. From September 2010, the temperature profiles measured showed a situation of strong stratification, however, the model was not able to reproduce such situation due to the low temperature values of estimated equilibrium temperature. The lag between the equilibrium temperature and the surface temperature of the water was only possible taking a constant coefficient of heat exchange. Case 5: Using a coefficient of heat exchange estimated from an analytical expression, the results showed that the surface temperature of the water and the equilibrium temperature were in phase and showed similar values. The Case 5 showed better agreement with the data compared to Case 4. Although in some situation the model has not reproduced the strong stratification observed, the proposal that the thermal regime of the Rio Verde Reservoir is influenced by the meteorological conditions proved to be quite satisfactory. Key-words: Thermal stratification of water bodies. Equation of one-dimensional heat transfer. Equilibrium temperature