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

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-02-10T11:07:35Z No. of bitstreams: 1 Jair Carlos Muller_.pdf: 2333529 bytes, checksum: 36c56be5b98f22351456fbe4e419d28f (MD5) / Made available in DSpace on 2017-02-10T11:07:35Z (GMT). No. of bitstreams: 1 Jair Carlos Muller_.pdf: 2333529 bytes, checksum: 36c56be5b98f22351456fbe4e419d28f (MD5) Previous issue date: 2016-10-04 / 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.

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 à 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 à 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.

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.

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

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

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.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-11-30T14:46:17Z No. of bitstreams: 1 Sérgio Luiz Bohrer Filho_.pdf: 1393460 bytes, checksum: 335661e44d51f93aa77abb3a780e6e5a (MD5) / Made available in DSpace on 2015-11-30T14:46:17Z (GMT). No. of bitstreams: 1 Sérgio Luiz Bohrer Filho_.pdf: 1393460 bytes, checksum: 335661e44d51f93aa77abb3a780e6e5a (MD5) Previous issue date: 2015-10-14 / 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.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-04-19T16:40:27Z No. of bitstreams: 1 Patricia Scalco_.pdf: 2617305 bytes, checksum: 329172a91dc38579cc85445e7b13abf1 (MD5) / Made available in DSpace on 2017-04-19T16:40:27Z (GMT). No. of bitstreams: 1 Patricia Scalco_.pdf: 2617305 bytes, checksum: 329172a91dc38579cc85445e7b13abf1 (MD5) Previous issue date: 2016-01-22 / 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%.

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.