Dissertations / Theses: 'Linear Fresnel'

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Pye, John Downing Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. "System modelling of the compact linear Fresnel reflector." Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/41244.

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The Compact Linear Fresnel Reflector is a solar thermal energy system currently at prototype stage in Australia. The system uses parallel rows of mirrors lined up underneath a long, elevated thermal absorber. The mirrors move so as to focus solar radiation onto the absorber; the absorber contains a bank of high-pressure water pipes through which water is pumped and gradually boils. The process of ??direct steam generation?? in very long pipes, up to 300 m in a straight run, has not previously been performed at this scale; other systems use shorter pipe runs, or use other fluids such as non-boiling oil. This thesis addresses a broad range of design issues relating to the CLFR prototype and its components. Beam solar radiation at the prototype site is estimated from available data including satellite-derived and ground-based measurements. Existing correlations for the beam component of global radiation do not apply well to Australian conditions so a new correlation is proposed. Computational fluid dynamics simulations establish radiative heat-loss as the dominant mode for the thermal absorber. Results are gathered for a range of sizes and shapes, and heat-loss correlations are derived for use in subsequent simulation. Two-phase flow in the absorber direct-steam-generation process is examined, and a detailed model including, pipe-friction pressure drops, flow-boiling heat transfer and cavity heat loss is presented, with validation against the experimental results of other workers. A series of ??performance maps?? give the predicted outlet flow regime for varied inlet conditions, allowing selection of desired operating points. A full system model is given that integrates this absorber model with ancillary components including the pump and connecting pipework; the model is used to evaluate pumping requirements and to establish expected operating conditions. The inherent pressure instability arising from the two phase flow is examined and orifice plates are sizes to stabilise this effect. A dynamic model for the absorber pipe flow using fully implicit finite difference techniques and accurate IAPWS-IF97 steam properties gives the predicted behaviour during solar transients at both long and short time-scales.

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Walker, Gregg Stuart. "Development of a low cost linear fresnel solar concentrator." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85762.

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Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: This study describes the design and construction of a low-cost linear Fresnel solar concentrator. Ray-trace simulation models that analyse optical performance were developed and then used to perform sensitivity analyses of various characteristics of linear Fresnel concentrators. The design of a small-scale concentrator was optimised using the simulation models, after which the concentrator was constructed in the solar laboratory. The concentrator consists of a single-motor tracking system, flat primary mirrors and a low-cost secondary concentrator that approximates a compound parabolic concentrator. Testing revealed satisfactory performance that was comparable to the simulation models’ prediction. The construction of a low-cost solar concentrator that can replace existing thermal sources for the generation of power and process heat is thus achievable.
AFRIKAANSE OPSOMMING: Die ontwerp en konstruksie van 'n laekoste- lineêre Fresnel-sonkonsentreerder word in hierdie studie beskryf. Stralingsimulasiemodelle wat optiese werksverrigting analiseer is ontwikkel en gebruik om sensitiwiteitsanalises van die verskillende eienskappe van lineêre Fresnel-konsentreerders te doen. Die modelle is verder gebruik om die ontwerp van 'n kleinskaalse konsentreerder te optimeer, waarna die konsentreerder in die sonlaboratorium gebou is. Die konsentreerder bestaan uit 'n enkelmotorvolgingstelsel, plat primêre spieëls en 'n laekoste- sekondêre konsentreerder soortgelyk aan 'n saamgestelde, paraboliese konsentreerder. Toetsing dui bevredigende werksverrigting aan, vergelykbaar met wat die simulasiemodelle voorspel het. Dit is dus moontlik om 'n laekoste-sonkonsentreerder wat bestaande termiese bronne vir kragopwekking en proseshittegenerasie kan vervang, daar te stel.

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Moghimi, Ardekani Mohammad. "Optical thermal and economic optimisation of a linear Fresnel collector." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/61313.

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Solar energy is one of a very few low-carbon energy technologies with the enormous potential to grow to a large scale. Currently, solar power is generated via the photovoltaic (PV) and concentrating solar power (CSP) technologies. The ability of CSPs to scale up renewable energy at the utility level, as well as to store energy for electrical power generation even under circumstances when the sun is not available (after sunset or on a cloudy day), makes this technology an attractive option for sustainable clean energy. The levelised electricity cost (LEC) of CSP with thermal storage was about 0.16-0.196 Euro/kWh in 2013 (Kost et al., 2013). However, lowering LEC and harvesting more solar energy from CSPs in future motivate researchers to work harder towards the optimisation of such plants. The situation tempts people and governments to invest more in this ultimate clean source of energy while shifting the energy consumption statistics of their societies from fossil fuels to solar energy. Usually, researchers just concentrate on the optimisation of technical aspects of CSP plants (thermal and/or optical optimisation). However, the technical optimisation of a plant while disregarding economic goals cannot produce a fruitful design and in some cases may lead to an increase in the expenses of the plant, which could result in an increase in the generated electrical power price. The study focused on a comprehensive optimisation of one of the main CSP technology types, the linear Fresnel collector (LFC). In the study, the entire LFC solar domain was considered in an optimisation process to maximise the harvested solar heat flux throughout an imaginary summer day (optical goal), and to minimise cavity receiver heat losses (thermal goal) as well as minimising the manufacturing cost of the plant (economic goal). To illustrate the optimisation process, an LFC was considered with 12 design parameters influencing three objectives, and a unique combination of the parameters was found, which optimised the performance. In this regard, different engineering tools and approaches were introduced in the study, e.g., for the calculation of thermal goals, Computational Fluid Dynamics (CFD) and view area approaches were suggested, and for tackling optical goals, CFD and Monte-Carlo based ray-tracing approaches were introduced. The applicability of the introduced methods for the optimisation process was discussed through case study simulations. The study showed that for the intensive optimisation process of an LFC plant, using the Monte Carlo-based ray-tracing as high fidelity approach for the optical optimisation objective, and view area as a low fidelity approach for the thermal optimisation objective, made more sense due to the saving in computational cost without sacrificing accuracy, in comparison with other combinations of the suggested approaches. The study approaches can be developed for the optimisation of other CSP technologies after some modification and manipulation. The techniques provide alternative options for future researchers to choose the best approach in tackling the optimisation of a CSP plant regarding the nature of optimisation, computational cost and accuracy of the process.
Thesis (PhD)--University of Pretoria, 2017.
Mechanical and Aeronautical Engineering
PhD
Unrestricted

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Ying, Xiaomin. "Statistical ray-tracing analysis of the linear Fresnel mirror solar concentrator." Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/897508.

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The Monte Carlo-type statistical ray-tracing method was used to investigate the performance of the line-focusing Fresnel mirror solar concentrator. An optical model of the line-focusing Fresnel mirror concentrator using the statistical ray-tracing approach was developed. Many rays of sunlight from the solar disk were selected at random and traced through the concentrator in this model. This optical model permits calculation of the local and geometric concentration ratios. The latter requires an energyloss analysis. Small sun-tracking errors of the diurnal or transverse type were included in the model.Based on the optical model and the Monte Carlo-type statistical ray-tracing method, a computer program was written implementing the model and computations using Pascal. To facilitate performance comparisons, a baseline concentrator design was adopted. To study the effects of imperfect tracking, performance data were generated for small tracking errors up to approximately two and one-half degrees. The selected mirror configuration permitted comparisons between the statistical approach and previous applications of the "extreme ray" analysis for an imperfectly tracking mirror concentrator.Simulation results demonstrated that the concentration characteristics are highly sensitive to the tracking error. The geometric concentration ratio dramatically decreases when the tracking error increases, which is the same as the "extreme ray" analysis. Results of some typical numerical calculations are presented graphically and discussed.
Department of Physics and Astronomy

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Negreiros, Igor Soares. "Development of a system tracking of solar concentrator prototype linear fresnel." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14016.

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Amid the great crisis of the energy, new methods for electric power generation, especially those do not harm the environment, are constantly sought to meet the growing need worldwide. Among them, the use of Fresnel linear concentrators becomes increasingly feasible, due to have lower cost in comparison to other types of solar concentrators. Thus, the project seeks to develop techniques that optimize use of the system where the main objective is to implement and validate the tracking system for a prototype of linear Fresnel solar concentrator, operating between approximately 7:30 and 16:30 in Fortaleza, CearÃ. For that, it used microcontrollers, sensors and motors to design a system capable of tracking Solar light system. The characterization and validation of the inductive position sensor used is also an important part of the work. To perform the tracking system, have been used a theoretical methodology for relative location of the sun, beyond the gain scheduling technique in control of employee movement. The position sensor validation have a maximum error than 0.3Â. Therefore, can consider that, with the use of the techniques employed for the achievement of system of control, the medium error obtained was about 0.06Â, making the design perform the concentration of solar rays in the absorber concentrator with a maximum deviation of 0.5Â, providing the desired reliability for system use.
Em meio Ãs grandes crises no ambiente energÃtico novos mÃtodos para geraÃÃo de energia elÃtrica, principalmente aqueles que nÃo agridem o meio ambiente, sÃo procurados constantemente para suprir a crescente necessidade mundial. Dentre eles, o uso de concentradores Solares do tipo Fresnel linear torna-se cada vez mais viÃvel, devido possuir custo inferior a outros tipos de concentradores solar. Com isso, procura-se desenvolver tÃcnicas que otimizem o uso do modelo onde o principal objetivo deste trabalho Ã implementar e validar o sistema de rastreamento de um protÃtipo de concentrador solar Fresnel linear, com funcionamento compreendido aproximadamente entre 7:30 e 16:30 h, na cidade de Fortaleza, CearÃ. Para tanto, utilizou-se microcontroladores, sensores e motores para projetar um sistema capaz de rastrear a luz Solar. A caracterizaÃÃo e validaÃÃo do sensor de posiÃÃo indutivo utilizado tambÃm Ã parte importante do trabalho. Para a realizaÃÃo do rastreamento empregou-se uma metodologia teÃrica para localizaÃÃo relativa do Sol, alÃm da tÃcnica de escalonamento de ganho no controle do movimento empregado. A validaÃÃo do sensor de posiÃÃo foi realizada encontrando-se um erro mÃximo em torno de 0,3Â. Portanto, pode-se considerar que, com a utilizaÃÃo das tÃcnicas abordadas para a realizaÃÃo do controle do sistema o erro mÃdio obtido foi cerca de 0,06Â, fazendo com que o projeto realizasse a concentraÃÃo dos raios solares no absorvedor do concentrador com um desvio mÃximo de 0.5Â, fornecendo ao sistema a confiabilidade desejada para sua utilizaÃÃo.

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Muller, Jair Carlos. "Estudo geométrico de um refletor fresnel linear para produção de energia térmica." Universidade do Vale do Rio dos Sinos, 2016. http://www.repositorio.jesuita.org.br/handle/UNISINOS/6031.

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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.

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Almeida, Geraldo Samuel Marques. "Pesquisa e desenvolvimento de um sistema termoelétrico do tipo linear fresnel reflector." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/9121.

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Dissertação para obtenção do Grau de Mestre em Energias Renováveis – Conversão Elétrica e Utilização Sustentável
A pesquisa de novos conceitos e materiais relacionados com a energia solar concentrada têm despertado o interesse dos mais variados grupos industriais e instituições científicas. Este interesse é justificado pelo baixo custo de investimento e pelos elevados rendimentos de conversão, que são típicos neste tipo de tecnologia solar. O projeto em curso não surgiu para resolver um problema concreto do mercado, ou da indústria de energia solar, mas sim, para desenvolver uma aplicação de pequena escala, para um concentrador solar inovador do tipo refletor linear Fresnel. Este projeto reveste-se de alguma importância para as energias renováveis. Pois, se for bem sucedido, uma pessoa comum poderá passar a produzir eletricidade e águas quentes. O projeto em curso aborda a metodologia necessária no desenvolvimento de um concentrador solar do tipo refletor linear Fresnel, nomeadamente as eficiências térmica e ótica. As quais estão relacionadas respetivamente com os aspetos de transferência de calor e com os parâmetros de construção. O protótipo é composto por seis refletores orientados para um recetor trapezoidal de cavidade aberta. Colocado no foco do recetor, encontra-se um absorvedor pintado com tinta seletiva. O recetor linear está elevado sobre os espelhos que possuem uma orientação norte-sul, favorável à captação dos raios solares ao longo do dia. O sistema desenvolvido mostrou durante os testes realizados em ambiente real, bons resultados ao nível da temperatura atingida e ao nível do rendimento ótico. Porém a experiência sugere que o seguimento solar neste tipo de concentrador seja uma questão a ser debatida em trabalhos futuros. Os dois objetivos que o projeto visa atingir são: a comparação entre o concentrador Disco Parabólico com o LFR e a implementação de um modo de armazenamento direto de calor.

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Negreiros, Igor Soares. "Desenvolvimento do sistema de rastreamento de um protótipo de concentrador solar fresnel linear." reponame:Repositório Institucional da UFC, 2015. http://www.repositorio.ufc.br/handle/riufc/11682.

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NEGREIROS, I. S. Desenvolvimento do sistema de rastreamento de um protótipo de concentrador solar fresnel linear. 2015. 115 f. Dissertação (Mestrado em Engenharia Elétrica) - Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2015.
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Amid the great crisis of the energy, new methods for electric power generation, especially those do not harm the environment, are constantly sought to meet the growing need worldwide. Among them, the use of Fresnel linear concentrators becomes increasingly feasible, due to have lower cost in comparison to other types of solar concentrators. Thus, the project seeks to develop techniques that optimize use of the system where the main objective is to implement and validate the tracking system for a prototype of linear Fresnel solar concentrator, operating between approximately 7:30 and 16:30 in Fortaleza, Ceará. For that, it used microcontrollers, sensors and motors to design a system capable of tracking Solar light system. The characterization and validation of the inductive position sensor used is also an important part of the work. To perform the tracking system, have been used a theoretical methodology for relative location of the sun, beyond the gain scheduling technique in control of employee movement. The position sensor validation have a maximum error than 0.3º. Therefore, can consider that, with the use of the techniques employed for the achievement of system of control, the medium error obtained was about 0.06°, making the design perform the concentration of solar rays in the absorber concentrator with a maximum deviation of 0.5°, providing the desired reliability for system use
Em meio às grandes crises no ambiente energético novos métodos para geração de energia elétrica, principalmente aqueles que não agridem o meio ambiente, são procurados constantemente para suprir a crescente necessidade mundial. Dentre eles, o uso de concentradores Solares do tipo Fresnel linear torna-se cada vez mais viável, devido possuir custo inferior a outros tipos de concentradores solar. Com isso, procura-se desenvolver técnicas que otimizem o uso do modelo onde o principal objetivo deste trabalho é implementar e validar o sistema de rastreamento de um protótipo de concentrador solar Fresnel linear, com funcionamento compreendido aproximadamente entre 7:30 e 16:30 h, na cidade de Fortaleza, Ceará. Para tanto, utilizou-se microcontroladores, sensores e motores para projetar um sistema capaz de rastrear a luz Solar. A caracterização e validação do sensor de posição indutivo utilizado também é parte importante do trabalho. Para a realização do rastreamento empregou-se uma metodologia teórica para localização relativa do Sol, além da técnica de escalonamento de ganho no controle do movimento empregado. A validação do sensor de posição foi realizada encontrando-se um erro máximo em torno de 0,3º. Portanto, pode-se considerar que, com a utilização das técnicas abordadas para a realização do controle do sistema o erro médio obtido foi cerca de 0,06º, fazendo com que o projeto realizasse a concentração dos raios solares no absorvedor do concentrador com um desvio máximo de 0.5º, fornecendo ao sistema a confiabilidade desejada para sua utilização

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Scalco, Patricia. "Análise óptica e térmica do receptor de um sistema de concentradores Fresnel lineares." Universidade do Vale do Rio dos Sinos, 2016. http://www.repositorio.jesuita.org.br/handle/UNISINOS/6231.

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CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico
O estudo de diferentes fontes de energia é de extrema importância, tanto em termos econômicos e sociais, como no âmbito ambiental. Assim, o uso da energia solar para a geração de calor para alimentar processos que necessitam de temperaturas em torno de 300 ºC aparece como uma alternativa para suprir o uso de combustíveis fósseis em ambientes industriais, seja de forma parcial ou total. Para atingir essa faixa de temperatura, devem ser utilizados equipamentos de alto desempenho e que possam concentrar ao máximo a radiação solar. Assim, é utilizada a tecnologia de refletores Fresnel lineares, que se baseia no princípio de concentração solar, onde os raios solares incidem em espelhos que refletem essa radiação para um receptor. O receptor é composto por um tubo absorvedor e por uma segunda superfície refletora, conhecida como concentrador secundário, que tem como função maximizar a quantidade de raios absorvidos pelo receptor. Esse tipo de instalação tem se mostrado competitiva diante de outros tipos de concentração solar devido à sua estrutura simples, custo reduzido e fácil manutenção. Assim, neste trabalho serão analisados aspectos ópticos e térmicos do conjunto do receptor, tanto para o concentrador secundário do formato trapezoidal como para o CPC. Para isso, o estudo foi dividido em duas etapas. Na primeira etapa foi feito o traçado de raios para as duas geometrias do concentrador secundário estudadas afim de determinar o fator de interceptação e as perdas ópticas envolvidas neste processo. Além disso, foi analisada a influência da inserção de uma superfície de vidro na base do receptor. A segunda etapa consistiu na análise térmica, onde foi feito o estudo da transferência de calor no receptor com a finalidade de determinar a eficiência do sistema, bem como os fatores que influenciam no desempenho do mesmo. Na análise geométrica, o fator de interceptação para a concentrador secundário do tipo trapezoidal foi de 36% para o receptor aberto e 45% para o receptor com o fechamento de vidro. Para o concentrador secundário do tipo CPC, os resultados foram de 44% para o receptor aberto e 56% para o receptor isolado com vidro. Através da análise térmica, foi possível estabelecer a eficiência do sistema que, para a melhor condição de trabalho, DNI de 1000 W/m², foi de 80%.
The study of different energy sources is extremely important, both in economic and social scope, as well as in the environmental field. Thus, the use of solar energy for the generation of heat to feed processes that require temperatures around 300 ºC appears as an alternative to supply the use of fossil fuels in industrial environments, either partially or totally. To reach this temperature range, high-performance equipment must be used that can concentrate solar radiation to the maximum. Thus, Fresnel linear reflector technology is used, which uses the principle of solar concentration, where the solar rays focus on mirrors that reflect this radiation to the receiver. The receiver is composed of an absorber tube and a second reflecting surface whose function is to maximize the number of rays absorbed by the receiver. This type of installation has been competitive in comparison to other types of solar concentration because of its simple structure, low cost and easy maintenance. Thus, in this work will be analyzed optical and thermal aspects of the receiver set for the trapezoidal and the CPC secondary concentrator. For this, the study was divided into two stages. In the first stage the ray tracing was done for the two geometries of the secondary concentrator studied in order to determine the interception factor and the optical losses involved in this process. In addition, the influence of insertion of a glass surface on the base of the receptor was isolated by isolating it from the environment. The second stage consisted of the thermal analysis, where the heat transfer study was carried out in the receiver in order to determine the efficiency of the system as well as the factors that influence the performance of the system. In the geometric analysis, the interception factor for the trapezoidal secondary concentrator was 36% for the open receptor and 45% for the receptor with the glass enclosure. For the CPC secondary concentrator, the results were 44% for the open receptor and 56% for the receptor with the glass enclosure. Through the thermal analysis, it was possible to establish the efficiency of the system, which, for the best working condition, DNI of 1000 W/m², was 80%.

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Schlaifer, Perrine. "Performance Calculations and Optimization of a Fresnel Direct Steam Generation CSP Plant with Heat Storage." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116806.

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This master thesis deals with the performance calculations of a 9MW linear Fresnel CSP plant withdirect steam generation built by the Solar Division of the CNIM Company. The aim was to calculate theannual electricity production taking into account the weather conditions as well as some steam storage.At first, a steam accumulator model was developed with Excel, in order to estimate the pressureevolution in the tanks during the charging, storage and discharging processes. The data obtained withthis model was then integrated to the thermodynamic cycle model, programmed with Excel, whichcalculated the electrical power production knowing the thermal power available in the solar field. Theelectricity production calculations were made every 600 seconds during one year.To improve the results accuracy, the influence of the plant location slope was estimated, calculating theequivalent azimuth and elevation angles in a new spherical coordinates system. For an average slope of4.21° at the plant location, the annual thermal energy gain is 14.4% (with a gain up to 60% duringwinter days) and the annual electricity production is increased by 12.59%. The influence of frost on themirrors during cold and humid nights was also estimated with a simple model of the energy needed toheat up a constant layer of ice. Depending on the assumptions, the electricity production losses werebetween 1.27 and 2.84% of annual electricity production. The losses due to plant shutdowns set by theelectrical network manager RTE during the snowmelt months were also estimated. The annualelectricity production could decrease by 8.02 to 11.57 % because of the load management, dependingon the days during which the plant is shutdown.Finally, an economic optimisation was led with prices estimated by CNIM, which gave an optimal solarfield design with 31 lines and 5 steam accumulators. The payback time would then be 9.887 years.

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Bohrer, Filho Sérgio Luiz. "Estudo de integração de energia heliométrica em uma termelétrica de ciclo combinado." Universidade do Vale do Rio dos Sinos, 2015. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4970.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares
Este trabalho apresenta um estudo de viabilidade de inserção de energia solar térmica na matriz elétrica brasileira, através de integração de um campo de energia termosolar concentrada com uma usina termelétrica de ciclo combinado localizada na Região Centro-Oeste. A atual conjuntura do setor elétrico, que apresenta crescimento do despacho termelétrico e consequente elevação dos custos de geração de energia elétrica, provocados principalmente por períodos de Energia Natural Afluente (ENA) abaixo da média, justifica o desenvolvimento de fontes alternativas. O objetivo principal deste estudo é apresentar um modelo de empreendimento de produção de eletricidade por meio de fonte solar térmica, compatível à realidade tecnológica e econômica do mercado de energia. O estudo baseia-se na simulação de integração de um campo solar com tecnologia de concentração Fresnel linear e geração direta de vapor superaquecido, junto à Usina Termelétrica Luís Carlos Prestes (UTE-LCP), no município de Três Lagoas, no estado de Mato Grosso do Sul. O desempenho do campo solar é verificado através do software System Advisor Model (SAM) da National Renewable Energy Laboratory (NREL) e a produção adicional de termeletricidade é determinada com base na análise de eficiência do ciclo de Rankine da UTE-LCP. Por fim, é realizada a análise financeira do projeto através de ferramentas de engenharia econômica, onde identifica-se um custo nivelado da energia elétrica (LCOE) de pelo menos 139,24 USD MW-1h-1, uma redução de 42,7% em relação às estimativas de custo internacionais para usinas heliotérmicas. Análises de sensibilidade indicam que o custo do capital tem impacto crítico sobre o LCOE, fato atribuído ao caráter de alta dependência dos recursos de capital da tecnologia solar térmica.
This work presents a study of concentrated solar power insertion in the Brazilian energy matrix, through integration of the solar energy with Luís Carlos Prestes Thermoelectric Power Plant (UTE-LCP) in Três Lagoas city. The current situation of the Brazilian electricity sector, which has presented strong growth of thermoelectric dispatch in recent years and the consequent increase in the cost of electricity generation, justifies the development of alternative energy sources. The purpose of this study is to present a model of electricity generation through thermal solar source compatible to technological and economic realities of the energy market. The study is based on evaluation of the linear Fresnel reflector with direct steam generation, because this configuration has investment, operation and maintenance attractive costs. The performance of the solar field is simulated in the System Advisor Model software (SAM) of the National Renewable Energy Laboratory (NREL). The predict performance is used with UTE-LCP operational database to estimate the additional electricity generation. Finally, the financial analysis is carried out through economic engineering tools, which identifies a Levelized Cost of Electricity (LCOE) of the 139.24 USD MW-1h-1 at least. This LCOE is 42.7% less than cost estimates for Concentrating Solar Power plants. Sensitivity analysis indicates that the cost of capital has critical impact on the LCOE, which was attributed to the character of high dependence on Concentrating Solar Power (CSP) capital resources.

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Woodrow, Oliver Rhys. "Characterisation of a parabolic trough collector using sheet metal and glass mirror strips." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/62804.

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A novel type of parabolic trough collector was characterised using a very basic theoretical model. This model looked at an ideal case and provided a basic expectation that was compared to actual measurements. The model showed that greater improvements can be achieved if heat losses to the environment are limited or omitted. This can be achieved by using a glass shield to insulate the receiver in a vacuum to limit the effect wind has and therefore limit convective losses. The experimental characterisation of the PTC consisted of taking six different temperature measurements to better understand the energy balances taking place. Four different configurations were tested, using two different types of concentrator and in each case a receiver that was either unpainted or painted with a semi matte black paint. The different types of concentrator were either stainless steel sheet metal or discretised glass mirror strips, similar to a linear Fresnel collector. Experimental runs were conducted on cloudless days for an hour and 15 minutes. This allowed for three runs to be performed on a single day. Using the theoretical model and comparing it to the experimental data, an efficiency was calculated. This efficiency averaged 14 % when the receiver was unpainted and 13 % when the receiver was painted for the metal sheets. The glass mirror strips had average efficiencies of 54 % and 45 % for an unpainted and painted receiver respectively. The model is very basic and can be improved upon if more variables are taken into consideration, such as convective heat losses. It was also recommended that wind measurements are taken in future tests. A property looked at to evaluate the effectiveness of each type of configuration was the average energy supplied to the thermal heating fluid over the course of an experimental run. For this the averaged values over all the experimental runs conducted for stainless steel sheet metal were 258 W and 332 W for an unpainted and painted pipe respectively. When using the glass mirrors an average energy value of 1049 W was supplied when the pipe was unpainted and an average of 1181 W was gained in the runs conducted after the pipe had been painted. Painting the receiver had little to no effect. The surface temperature of the receiver after painting the pipe was not higher and a slight increase in the energy gained by water was observed. This was explained by inaccuracies during testing as scattered light may have caused an interference on some of the measurements. There were also human inaccuracies in testing which should be omitted in future tests by implementing, for one, a functional tracking system. Future tests should be designed in such a way to completely omit irradiance affecting the thermocouple taking the measurement. Glass mirrors fared far better than the stainless steel sheet metal counterpart. It was recommended that they are used as the concentrator of choice. Higher efficiencies were achieved and in some cases almost four times the energy was supplied to the water in the pipe. This was attributed to a much lower concentrator temperature, on average 11 °C lower than the temperature of the metal sheets, as well as a much better ability to concentrate sunlight onto a single focal point. However, the glass mirror strips were proven to be very fragile and as such, require protection from the elements. While the strips were lighter and caused less of a load during windy conditions, they were susceptible to oscillations from gusty wind. This led to a number of strips breaking and needed to be replaced. By discretising the strips into individual pieces, they had the benefit of only needing to replace the strips that were damaged. This is also true for all future runs. It is still recommended that a tarp be used to protect the glass mirrors. Using glass mirror strips as a concentrator combined LFC technology with PTC technology and a novel PTC design was achieved. The design still required the installation area of a PTC. The novel design was compared to Industrial Solar’s industrial LFC module, LF-11, as it shares many similarities to LFC technology. The peak thermal output of the rig was significantly lower at 346 W/m2 compared to the industrial value of 562 W/m2. However, the noteworthy differences in design and optimisation between the two modules meant the results achieved were comparable. It is expected that better and more comparable results can be realised once the inherent flaws in the design, such as tracking the sun, aperture size and adding a vacuum absorber, are addressed. It is recommended that more research and emphasis is put into this field as an alternative energy power plant for South Africa.
Dissertation (MEng)--University of Pretoria, 2017.
Chemical Engineering
MEng
Unrestricted

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Ko, Gaelle Kafira. "Etude et modélisation dynamique d'un concentrateur à miroir linéaire de Fresnel." Thesis, Perpignan, 2019. http://www.theses.fr/2019PERP0018/document.

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Parmi les technologies de solaire thermodynamique, la technologie du linéaire de Fresnel semble la plus adaptée aux régions d’Afrique Sub saharienne. Cela en raison de la simplicité de la technologie. C’est dans cette optique qu’un collecteur de type linéaire de Fresnel d’une superficie de 7,5 m² de miroirs a été construit au laboratoire énergies renouvelables et efficacité énergétique (LabEREE). La construction du collecteur s’est faite en utilisant en priorité les matériaux disponibles localement afinde rendre la technologie plus accessible aux populations locales et de réduire les coûts de fabrication. Des tests sont effectués sur le collecteur afin de déterminer ses rendements optiques, thermiques et globaux. Dans un premier temps, une revue bibliographie des différents collecteurs de type linéaire de Fresnel nous a permis d’identifier les variantes, de cette technologie, les plus adaptées au contexte dela région . Un modèle thermique et un modèle optique ont été mis en place comme outils de dimensionnement et d’optimisation du collecteur. Les résultats expérimentaux obtenus ont été utilisés pour valider les différents modèles mis en place. Le rendement global du collecteur obtenu expérimentalement est de 21% et il a un facteur de concentration local de 6
Among the different technologies of concentrated solar power plant, the linear Fresnel, thanks to its simplicity, appears the most adapted to rural area of Sub Sahara region. A linear Fresnel collector of 7.5 m² has been built in “laboratoire énergies renouvelables et efficacité énergétique (LabEREE)”. The collector have been designed using material available locally by local man power. This reduces the total cost of the technology and makes it affordable for local population. The collector has been characterized in order to find optical, thermal and global efficiencies. In first time, a review on different linear Fresnel collector allows finding the technology that is most adapted to the Sub-Saharan region. An optical and thermal model of the collector has been done as a tool for designing and optimisation. The experimental results enable to validate the different models done. The collector has an effective concentration factor of 6 and a global efficiency of 21%

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Veynandt, François. "Cogénération héliothermodynamique avec concentrateur linéaire de Fresnel : modélisation de l’ensemble du procédé." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0116/document.

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Le concentrateur à réflecteur linéaire de Fresnel (LFR) est une technologie solaire thermodynamique en plein essor : petites applications industrielles (chaleur, froid, électricité) à centrales électriques (10-100 MWel). Ce travail de thèse établit un modèle global du procédé solaire, en régime permanent, pour un prédimensionnement du système. Le modèle comprend trois parties chaînées : (i) les transferts radiatifs dans le concentrateur optique, modélisés précisément par une méthode de Monte Carlo (environnement EDStar) ; (ii) les transferts thermiques dans le récepteur, évalués analytiquement (puissances, températures) ; (iii) le cycle thermodynamique, avec Thermoptim. L’application étudiée couple un concentrateur LFR à un moteur Ericsson. L’air est fluide caloporteur et de travail. Un prototype est en construction. L’hybridation et le stockage thermique sont des options clés. Un modèle systémique permettrait d’optimiser l’opération du procédé, en étudiant son comportement dynamique
Linear Fresnel Reflector (LFR) is a promising Concentrating Solar Power technology. Research is booming and industrial applications are emerging. Applications range from small production units (heat, cold, electricity) to utility scale power plants (several tenths of MW). This PhD work establishes a global model of the solar process, in order to improve our knowledge of the system’s performances. It is a static model suited for a pre-design of the system. The model is chaining three parts. Radiative heat transfer in the optical concentrator is modelled by Monte Carlo statistical Method. The algorithm enables a detailed study of any geometrical configuration, especially through absorbed power flux maps on the receiver. The simulation tool is using the environment of development EDStar. The thermal model calculates analytically the useful thermal power, losses and temperature profiles along the receiver (glass cover, fluid, pipe...). The thermodynamic cycle is simulated analytically using the software Thermoptim. The studied application uses air as heat transfer and working fluid. Air directly feeds an Ericsson engine. The engine developed by LaTEP laboratory is promising for small scale cogeneration (1 to several tenths of kWel). The prototype Linear Fresnel Reflector built in Ecole des Mines d’Albi will enable experimental study of a solar process coupling an LFR concentrator and an Ericsson engine. The technology under study can feed a power plant or a cogeneration system in the industry, producing electricity and heat at 100 to 250°C. Hybridisation with an other energy source (biomass, gas...) and thermal storage (molten salt?) are key features to investigate. To optimise the operating strategy of the process, dynamic behaviour must be studied: a systemic or agent based model is a very relevant approach

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Mokhtar, Marwan M. [Verfasser], and R. [Akademischer Betreuer] Stieglitz. "Control of Solar Thermal Linear Fresnel Collector Plants in Single Phase and Direct Steam Generation Modes / Marwan M. Mokhtar ; Betreuer: R. Stieglitz." Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1177147130/34.

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Chaves, Anderson Silva. "Novos resultados teóricos e experimentais para a técnica Z-scan." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-15072010-094531/.

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O índice de refração não-linear n2 é o parâmetro chave da não-linearidade de terceira ordem em materiais ópticos. Um método simples, direto e sensível para medição do índice de refração não-linear (n2) é a técnica Z-scan proposta Sheik-Bahae et al 1. Nesse trabalho, um estudo sistemático quanto a esta técnica foi realizado. Utilizando a integral de difração de Fresnel-Kirchhoff, foi possível analisar a técnica investigando a influência do raio de abertura da íris. Foram obtidas expressões analíticas inéditas quando consideramos baixas não-linearidades induzidas por amostras finas. Esses resultados mostraram que o valor de n2 obtido é aproximadamente 36% maior do que n2 obtido por Sheik-Bahae para abertura linear de S=0,5, por exemplo.Extensões da técnica foram feitas, onde simulações para testar a viabilidade de medidas Z-scan no campo próximo e com dois feixes foram realizadas, de onde também foi possível encontrar resultados analíticos inéditos. Esses resultados teóricos foram testados tanto para feixe único quanto duplo em alguns experimentos, sendo obtido um bom acordo. Por fim, um novo método para medição do índice de refração não-linear não-degenerado foi proposto, em que é possível obter n2 no comprimento de onda do feixe de prova, num experimento com dois feixes. Esse resultado é importante uma vez que, em muitos casos, não é possível a realização de uma medida Z-scan convencional, devido ao fato da amostra não absorver o comprimento de onda do feixe de prova. Um resultado de n2 para rubi em 633nm foi obtido em bom acordo com resultados prévios da literatura, em que foram utilizadas técnicas de maior complexidade experimental.
The nonlinear refractive index n2 is the key parameter of the third order nonlinearity of optical materials. A simple, direct and sensitive measurement of nonlinear refractive index n2 is so-called Z-scan technique proposed by Sheik Bahae et al 1. In this work, a systematic study on this technique was performed. Based on Fresnel-Kirchhoff diffraction integral formula, it was possible to analyze the technique in order to investigate the influence of the apertures radius. We obtained unpublished analytical expressions when we consider small nonlinearities induced by thin samples. These results showed that the value of n2 obtained is about 36% larger than n2 obtained by Sheik-Bahae when the linear opening is 50%, for example.Extensions about the technique were made. Simulations were performed in order to test the feasibility of near-field Z-scan and two-color Z-scan measurements. Again it was also possible to find unpublished analytical results. The theoretical results were tested in some experiments and good agreement was found. Finally, a new method for measuring the nondegenerate refractive index was proposed. So, there is the possibility to obtain n2 at the wavelength of the probe beam in a two-color Z-scan experiment. This result is important since in many cases is impossible to perform a conventional z-scan measurement, due to the fact that the sample does not absorb the wavelength of the probe beam. A result of n2 for ruby at 633nm was obtained in good agreement with previous studies.

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Ion, Valentina. "Nonlinear approaches for phase retrieval in the Fresnel region for hard X-ray imaging." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-01015814.

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The development of highly coherent X-ray sources offers new possibilities to image biological structures at different scales exploiting the refraction of X-rays. The coherence properties of the third-generation synchrotron radiation sources enables efficient implementations of phase contrast techniques. One of the first measurements of the intensity variations due to phase contrast has been reported in 1995 at the European Synchrotron Radiation Facility (ESRF). Phase imaging coupled to tomography acquisition allows threedimensional imaging with an increased sensitivity compared to absorption CT. This technique is particularly attractive to image samples with low absorption constituents. Phase contrast has many applications, ranging from material science, paleontology, bone research to medicine and biology. Several methods to achieve X-ray phase contrast have been proposed during the last years. In propagation based phase contrast, the measurements are made at different sample-to-detector distances. While the intensity data can be acquired and recorded, the phase information of the signal has to be "retrieved" from the modulus data only. Phase retrieval is thus an illposed nonlinear problem and regularization techniques including a priori knowledge are necessary to obtain stable solutions. Several phase recovery methods have been developed in recent years. These approaches generally formulate the phase retrieval problem as a linear one. Nonlinear treatments have not been much investigated. The main purpose of this work was to propose and evaluate new algorithms, in particularly taking into account the nonlinearity of the direct problem. In the first part of this work, we present a Landweber type nonlinear iterative scheme to solve the propagation based phase retrieval problem. This approach uses the analytic expression of the Fréchet derivative of the phase-intensity relationship and of its adjoint, which are presented in detail. We also study the effect of projection operators on the convergence properties of the method. In the second part of this thesis, we investigate the resolution of the linear inverse problem with an iterative thresholding algorithm in wavelet coordinates. In the following, the two former algorithms are combined and compared with another nonlinear approach based on sparsity regularization and a fixed point algorithm. The performance of theses algorithms are evaluated on simulated data for different noise levels. Finally the algorithms were adapted to process real data sets obtained in phase CT at the ESRF at Grenoble.

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Lin, Qinglong. "Etude, modélisation dynamique et développement d'un capteur solaire thermique à concentration de nouvelle génération." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10099.

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Ce travail a pour objet de développer une nouvelle technologie de l’énergie solaire à concentration. Il porte sur la présentation du concept, la réalisation prototypique et l’étude optique et énergétique d’un nouveau concentrateur solaire QingSun™. Ce concentrateur a une forme de parallélépipède rectangulaire et comporte des lentilles de Fresnel linéaires, des parois tapissées de miroir et d’un récepteur solaire mobile entraîné par un système de suivi à l’intérieur du caisson de concentration. Un modèle optique et un modèle énergétique ont été élaborés et validés avec une série d’expériences. Ils ont permis d’étudier le fonctionnement et les performances énergétiques du concentrateur. Une étude de l’influence paramétrique de l’inclinaison et l’orientation a été effectuée et a montré que l’inclinaison a plus d’influence que l’orientation sur les performances. Enfin, les performances énergétiques optimales du concentrateur ont été estimées
This work is for the purpose to develop a new solar concentrating technology. It covers the presentation of the concept, the prototype realization and the optical and energy study of a new solar concentrator QingSun™. This concentrator has a shape of rectangular parallelepiped and includes linear Fresnel lenses, mirror-lined walls and a mobile solar receptor controlled by a tracking system inside the casing. An optical model and an energy model were developed and validated with a series of experiments. The both models permitted us to examine the function and the energy performance of the concentrator. A parametric study of the influence of the tilt and the orientation was performed and showed that the tilt had more influence than the orientation. Finally, the optimal energy performance of this concentrator was estimated

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Abeywardana, Asela Janaka. "Solar - Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-23794.

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This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel. Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels. When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area. This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.

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Pacini, Alberto. "Onde elettromagnetiche in mezzi continui, lineari, omogenei ed isotropi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21615/.

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In questa tesi viene discussa la propagazione delle onde elettromagnetiche nei continui in particolare nei mezzi lineari, omogenei, isotropi e dispersivi. Dal principio di causalità si derivano le relazioni di Kramers-Kronig che risultano quindi molto generali. Come applicazione della teoria sviluppata vengono inoltre ricavate le relazioni di Snell-Cartesio e le relazioni di Fresnel.

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Rosing, Kathrin [Verfasser], and Michael [Akademischer Betreuer] Frese. "Dynamics of the innovation process: The linear-recursive model of innovation and the implications for leadership and self-regulation / Kathrin Rosing. Betreuer: Michael Frese." Lüneburg : Universitätsbibliothek der Leuphana Universität Lüneburg, 2011. http://d-nb.info/1034292064/34.

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Dolorier, Castillo Carlos Augusto. "Dimensionamiento de un nuevo concentrador parabólico compuesto (CPC) con doble absorbedor de un colector lineal fresnel (LFC), aplicado como caso de estudio en la comunidad Alto Andina de Pilpichaca en la región Huancavelica sobre 4000 MSNM." Master's thesis, Pontificia Universidad Católica del Perú, 2017. http://tesis.pucp.edu.pe/repositorio/handle/123456789/12756.

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En el presente trabajo de Tesis se desarrolla el dimensionamiento y evaluación simulada de un nuevo Concentrador Parabólico Compuesto (CPC) de un Colector Lineal Fresnel (LFC), que tiene la característica de operar con 2 tuberías de absorción en lugar de una como en el modelo estándar, particularidad que le da ventajas ópticas, térmicas y proyección a mejores prestaciones operativas, por su disposición como tubería continua preparada para recirculación. El estudio de sus posibilidades energéticas de servicio, se centra en la localidad altoandina de Pilpichaca ubicada en el departamento de Huancavelica en la serranía del Perú, poseedora de un alto potencial solar pero de climatología fría por la gran altitud de su localización geográfica. De manera introductoria se presentan los aspectos generales de la tecnología de los LFCs y de los CPCs señalando sus características y su desarrollo actual. En el capítulo 1, se abordan los conceptos teóricos necesarios para el diseño y el análisis posterior, se exponen las ecuaciones implicadas, para el tratamiento de temas como: Geometría y Óptica solar, Transferencia de Calor y Masa y Termodinámica Aplicada, para hallar los resultados que servirán para medir el performance operativo del nuevo CPC propuesto como solución técnica. En el capítulo 2, se expone la metodología que será aplicada para realizar el pre dimensionamiento, análisis, evaluación y validación del nuevo diseño de CPC, presentando la secuencia lógica del flujo de tareas necesarias. En el capítulo 3, se realiza la caracterización energética y climática de la zona Caso de Estudio, también se desarrolla la evaluación del recurso en términos de encontrar la radiación solar directa (DNI) del sitio para los meses estacionales del año, a partir de hallar los ángulos solares característicos y luego aplicar modelos matemáticos de distribución horaria de valoración. En este capítulo también se trata un aspecto importante que es el dimensionamiento básico del LFC en cuanto a la configuración de su Campo de Espejos y la altura eficiente de ubicación del CPC. En el capítulo 4, se realiza el dimensionamiento geométrico y óptico del CPC propuesto, fundamentado en las teorías de optimización de flujo y uniformidad de distribución, para ello se utiliza la técnica de Trazado de Rayos Ray-Tracing- Montecarlo, a través de un software especializado de cálculo numérico, probando varios arreglos de CPCs y realizando contrastación de logros energéticos, esta tarea luego se extiende al modelo estándar para hallar las ventajas ópticas definitivas de la nueva propuesta. En el capítulo 5, se desarrolla el Balance Energético en las Tuberías de Absorción del nuevo CPC, para ello se configura una matriz climática de la zona, para hacerla interactuar con las propiedades térmicas de los materiales a través del modelo matemático de ecuaciones de conservación de masa y energía, y obtener los resultados de los rendimientos alcanzados por la instalación, bajo las Leyes de la Termodinámica. En el capítulo 6, se hace la discusión de los resultados obtenidos y sus implicancias sobre los logros alcanzados por el nuevo diseño de CPC frente al modelo estándar, haciendo las aclaraciones relevantes sobre los puntos más sensibles encontrados. Finalmente se concluye el estudio, validando la ventajas técnicas alcanzadas por el nuevo diseño de CPC en el aprovechamiento solar como energía de calor para procesos, para las aplicaciones identificadas como brecha energética, y otras actividades de fomento de desarrollo socioeconómico para la comunidad usuaria, al término se realizan las recomendaciones sobre puntos de atención sobre el tema y futuros trabajos a ser tratados.
Tesis

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Pavelec, Jiří. "Vývoj lineárního posuvu pro UHV STM/AFM." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229812.

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The aim of this diploma thesis is to develop a linear positioning stage for Ultra High Vacuum (UHV) environment. Simple prototypes of the linear positioning stage were designed and incorporated as part of a multiaxis sample manipulator for a UHV Scanning Tunneling Microscopy / Atomic Force Microscopy (STM/AFM). Different types of position encoders and linear guideways are discussed. Implementation of the homodyne interferometer as an optimization tool for a slip-stick based linear stage is described. Scalar diffraction theory is used to model the diffraction grating optical position encoder behavior.

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CHENG, DONG-SHENG, and 鄭東昇. "Linear Fresnel Lens For Solar Concentration PV SystemLinear Fresnel Lens For Solar Concentration PV SystemLinear Fresnel Lens For Solar Concentration PV System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/65887734137579555598.

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碩士
明志科技大學
機電工程研究所
96
The energy resources of earth are major goods and materials to humanity, almost the develop of industry and human life is by the natural resources, but the energy resources of earth will be exhaust by the human being, under the multiple’s pressure, The solar energy was abundant application, because of that, the solar energy technology has a advance by leaps and bounds. The purpose of this thesis is to design a linear non-image Fresnel lens,use the Fresnel lens with larger incidence angles to proceed the solar concentrator to generate electric power of GaAs solar cell,in the research include the optical simulate & manufacture of arched Fresnel lens、efficiency measure of GaAs solar cell. We get a attestation in the experiment, if the illumination are ampilifide with the efficiency of solar cell augment too, but if the temperature of solar cell are raised, the efficiency of solar cell will go down. Through the combine of solar concentrator with GaAs solar cell, to heighten the efficiency of High concentration PV system and cost down.

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25

Liu, Ying-Lin, and 劉盈麟. "THE STUDY Of LINEAR FOCUS FRESNEL LENS DESIGN AND FORMING ANALYSIS." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/01132311480829057637.

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碩士
國立高雄應用科技大學
模具工程系
98
This paper applies to solar energy for the linear focus Fresnel lens with the purpose of focusing sunlight 20mm long 100 mm wide flat panel solar collector on. This research analyzes three kinds of different inclination angles by using optical analysis software Tracepro for 60°、75°、90° the Fresnel lens. Sectional shape of the lens are all axis 120 mm, 60 mm short axis of the ellipse, the oval mirror each pitch are all small mausoleum 0.5 mm, comparing the optical path, energy loss and the angle of sunlight allowed. The experiment design of Taguchi method is adopted to determine the influence of different precess parameters (mold temperature, melt temperature, injection time, cooling time, packing pressure, packing pressure). Finally the optimum parameter combination for the mold temperature 80℃, melt temperature 243℃, injection time 0.6964s,cooling time 40s, packing pressure 90%, packing time 8s are found. The maximum warpage value is 0.3818mm.

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26

EscobarSantacruz, Agustin Wladimiro, and 艾斯汀. "Analysis and experimental investigation of a solar collector system with linear fresnel lenses." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/90313972962550103863.

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碩士
國立成功大學
航空太空工程學系碩博士班
100
Solar collector systems are starting to play an important role in today’s world. Solar collectors system which utilizes linear Fresnel lenses as the concentrators are a good alternative in the area of medium temperature concentrators. In this research; a solar thermal collector system that uses linear Fresnel lenses was investigated and analyzed; the system was designed and then built, after the collector and the receiver were placed, experiments began; different measurements were made to collect useful data. A physical model to simulate the collector was developed to study the performance of the system. Experimental results were compared to the results obtained in the simulated model and the deviation was found to be around 7%. The physical model was used as well to simulate the system at higher inlet temperatures. It was possible to see that the system performed well at temperatures up to 250℃ achieving an average efficiency of 50%. This showed that this type of collector is a relatively good alternative in solar thermal applications.

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27

Lin, Jia-Wei, and 林家瑋. "The Study of Linear Fresnel Lens Design and Injection Molding Analysis for Concentrator Photovoltaic." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/56100531410354056221.

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碩士
國立高雄應用科技大學
模具工程系
99
This paper is the application of concentrator photovoltaic the linear Fresnel lens design and analysis. This design aims to focus sunlight on 80mm long and 20mm wide flat panel solar collector. The thesis is a parabolic section of the linear Fresnel lens to the optical analysis software Tracepro and the mold flow analysis software for analysis. Lens design five kinds of different inclination angles, the use of optical analysis software and compare the path of light, energy loss and angle of sunlight , while the lens inclination angles have 60°, 65°, 70°, 75°, 80°. Analysis of optical software designed to get good lens inclination angle 60° into the mold flow analysis software for injection molding analysis.The use of Taguchi method, with a minimum goal of warping is the quality of products to find the best combination of Parameters in experiment.Control parameters and the optimum combination of parameters for the mold temperature (80℃), melting temperature (278.1℃), injection time (0.6810 sec), holding pressure (60MPa), and holding time (12 sec), the warpage value scope is 0.0140 ~ 0.2661 (mm), the total warpage value is 0.2521 (mm).

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28

Chen, Gong. "Linear Fresnel zone plate based two-state alignment system for 0.25 micron x-ray lithography." 1993. http://catalog.hathitrust.org/api/volumes/oclc/31041997.html.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1993.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 152-162).

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29

Chen, Hong-Yi, and 陳宏奕. "Linear Fresnel Lens and Free-Form Lens Design Using Natural Light and LED as Combing Light Source for Tunnel Lighting." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/52ugz6.

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碩士
國立臺灣科技大學
光電工程研究所
107
Traditional tunnel lighting has the problem of poor lighting environment and huge energy consumption. In this study, two different lenses were designed with natural light and LED as the light source. When the sunlight is enough, the natural light illumination system is used to give tunnel illumination in the threshold zone and the exit zone to reduce the LED usage. When the sunlight is not enough, the LED can complement the tunnel lighting. In terms of the two designs, the linear Fresnel lens is established as a light-emitting element of a natural light illumination system with a microstructure, and the free-form surface asymmetric lens of the LED is established by the catadioptric method. The two lenses are verified by the optical simulation software FRED. The uniformity on the road surface can reach about 84.8 and 80.2, and the efficiency are about 78.3% and 84.8% respectively. The model of the Hsueh-Shan tunnel was established by DIALux, and the two kinds of lenses were simulated in the tunnel in three modes. The mode 1 is only used with linear Fresnel lens when sunlight is enough. The mode 2 is only LED lighting when there is no sunlight. The mode 3 is hybrid lighting with the two kinds sources at the same time, which can adjust the lighting ratio of LED according to the intensity of natural light to save energy. As a result, the three modes can meet the first section is greater than 120cd/m2, the second section is greater than 60cd/m2 in the threshold zone and the first section is greater than 30cd/m2, the second section is greater than 15cd/m2 in the exit zone, the total uniformity U0 is greater than or equal to 0.4, longitudinal uniformity U1 is greater than or equal to 0.6. Finally, this study solves three problems. First, uses LED as the light source, and uses optical design to improve the problem that the traditional high-pressure sodium lamp itself is too high to causes glare. Second, the average illuminance method is used to calculate the most appropriate lamp spacing and reduce the zebra pattern on the road surface. Third, combines the natural light and the artificial light source, when the outdoor luminance is the highest, the natural light replaces the traditional tunnel light to be fully open. When the natural light energy is reduced, the LED is used to supplement the tunnel lighting to maintain the tunnel lighting environment. The tunnel lights do not need to operate 24 hours a day to save energy.

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30

Van, Rooy Willem. "Solar thermal augmentation of the regenerative feed-heaters in a supercritical Rankine cycle with a coalfired boiler / W.L. van Rooy." Thesis, 2015. http://hdl.handle.net/10394/15901.

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Conventional concentrating solar power (CSP) plants typically have a very high levelised cost of electricity (LCOE) compared with coal-fired power stations. To generate 1 kWh of electrical energy from a conventional linear Fresnel CSP plant without a storage application, costs the utility approximately R3,08 (Salvatore, 2014), whereas it costs R0,711 to generate the same amount of energy by means of a highly efficient supercritical coal-fired power station, taking carbon tax into consideration. This high LCOE associated with linear Fresnel CSP technology is primarily due to the massive capital investment required per kW installed to construct such a plant along with the relatively low-capacity factors, because of the uncontrollable solar irradiation. It is expected that the LCOE of a hybrid plant in which a concentrating solar thermal (CST) station is integrated with a large-scale supercritical coal-fired power station, will be higher than that of a conventional supercritical coal-fired power station, but much less than that of a conventional CSP plant. The main aim of this study is to calculate and then compare the LCOE of a conventional supercritical coal-fired power station with that of such a station integrated with a linear Fresnel CST field. When the thermal energy generated in the receiver of a CST plant is converted into electrical energy by using the highly efficient regenerative Rankine cycle of a large-scale coal-fired power station, the total capital cost of the solar side of the integrated system will be reduced significantly, compared with the two stations operating independently of one another for common steam turbines, electrical generators and transformers, and transmission lines will be utilised for the integrated plants. The results obtained from the thermodynamic models indicate that if an additional heat exchanger integration option for a 90 MW (peak thermal) fuel-saver solar-augmentation scenario, where an annual average direct normal irradiation limit of 2 141 kWh/m2 is considered, one can expect to produce approximately 4,6 GWh more electricity to the national grid annually than with a normal coal-fired station. This increase in net electricity output is mainly due to the compounded lowered auxiliary power consumption during high solar-irradiation conditions. It is also found that the total annual thermal energy input required from burning pulverised coal is reduced by 110,5 GWh, when approximately 176,5 GWh of solar energy is injected into the coal-fired power station’s regenerative Rankine cycle for the duration of a year. Of the total thermal energy supplied by the solar field, approximately 54,6 GWh is eventually converted into electrical energy. Approximately 22 kT less coal will be required, which will result in 38,7 kT less CO2 emissions and about 7,6 kT less ash production. This electricity generated from the thermal energy supplied by the solar field will produce approximately R8,188m in additional revenue annually from the trade of renewable energy certificates, while the reduced coal consumption will result in an annual fuel saving of about R6,189m. By emitting less CO2 into the atmosphere, the annual carbon tax bill will be reduced by R1,856m, and by supplying additional energy to the national grid, an additional income of approximately R3,037m will be due to the power station. The annual operating and maintenance cost increase resulting from the additional 171 000 m2 solar field, will be in the region of R9,71m. The cost of generating 1 kWh with the solar-augmented coal-fired power plant will only be 0,34 cents more expensive at R0,714/kWh than it would be to generate the same energy with a normal supercritical coal-fired power station. If one considers that a typical conventional linear Fresnel CSP plant (without storage) has an LCOE of R3,08, the conclusion can be drawn that it is much more attractive to generate electricity from thermal power supplied by a solar field, by utilising the highly efficient large-scale components of a supercritical coal-fired power station, rather than to generate electricity from a conventional linear Fresnel CSP plant.
MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

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