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Optimisation criteria of a Rankine steam cycle powered by thorium HTR / Steven Cronier van NiekerkVan Niekerk, Steven Cronier January 2014 (has links)
HOLCIM has various cement production plants across India. These plants struggle to
produce the projected amount of cement due to electricity shortages. Although coal is
abundant in India, the production thereof is in short supply.
It is proposed that a thorium HTR (100 MWt) combined with a PCU (Rankine cycle) be
constructed to supply a cement production plant with the required energy. The Portland
cement production process is investigated and it is found that process heat integration is not
feasible.
The problem is that for the feasibility of this IPP to be assessed, a Rankine cycle needs to be
adapted and optimised to suit the limitations and requirements of a 100 MWt thorium HTR.
Advantages of the small thorium HTR (100 MWt) include: on-site construction; a naturally
safe design and low energy production costs. The reactor delivers high temperature helium
(750°C) at a mass flow of 38.55 kg/s. Helium re-en ters the reactor core at 250°C.
Since the location of the cement production plant is unknown, both wet and dry cooling tower
options are investigated. An overall average ambient temperature of India is used as input
for the cooling tower calculations.
EES software is used to construct a simulation model with the capability of optimising the
Rankine cycle for maximum efficiency while accommodating various out of the norm input
parameters. Various limitations are enforced by the simulation model.
Various cycle configurations are optimised (EES) and weighed against each other. The
accuracy of the EES simulation model is verified using FlowNex while the optimised cycle
results are verified using Excel’s X-Steam macro.
It is recommended that a wet cooling tower is implemented if possible. The 85% effective
heat exchanger delivers the techno-economically optimum Rankine cycle configuration. For
this combination of cooling tower and heat exchanger, it is recommended that the cycle
configuration consists of one de-aerator and two closed feed heaters (one specified).
After the Rankine cycle (PCU) has been designed and optimised, it is evident that the small
thorium HTR (100 MWt) can supply the HOLCIM plant with the required energy. The optimum cycle configuration, as recommended, operates with a cycle efficiency of 42.4%
while producing 39.867 MWe. A minimum of 10 MWe can be sold to the Indian distribution
network at all times, thus generating revenue. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014
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Optimisation criteria of a Rankine steam cycle powered by thorium HTR / Steven Cronier van NiekerkVan Niekerk, Steven Cronier January 2014 (has links)
HOLCIM has various cement production plants across India. These plants struggle to
produce the projected amount of cement due to electricity shortages. Although coal is
abundant in India, the production thereof is in short supply.
It is proposed that a thorium HTR (100 MWt) combined with a PCU (Rankine cycle) be
constructed to supply a cement production plant with the required energy. The Portland
cement production process is investigated and it is found that process heat integration is not
feasible.
The problem is that for the feasibility of this IPP to be assessed, a Rankine cycle needs to be
adapted and optimised to suit the limitations and requirements of a 100 MWt thorium HTR.
Advantages of the small thorium HTR (100 MWt) include: on-site construction; a naturally
safe design and low energy production costs. The reactor delivers high temperature helium
(750°C) at a mass flow of 38.55 kg/s. Helium re-en ters the reactor core at 250°C.
Since the location of the cement production plant is unknown, both wet and dry cooling tower
options are investigated. An overall average ambient temperature of India is used as input
for the cooling tower calculations.
EES software is used to construct a simulation model with the capability of optimising the
Rankine cycle for maximum efficiency while accommodating various out of the norm input
parameters. Various limitations are enforced by the simulation model.
Various cycle configurations are optimised (EES) and weighed against each other. The
accuracy of the EES simulation model is verified using FlowNex while the optimised cycle
results are verified using Excel’s X-Steam macro.
It is recommended that a wet cooling tower is implemented if possible. The 85% effective
heat exchanger delivers the techno-economically optimum Rankine cycle configuration. For
this combination of cooling tower and heat exchanger, it is recommended that the cycle
configuration consists of one de-aerator and two closed feed heaters (one specified).
After the Rankine cycle (PCU) has been designed and optimised, it is evident that the small
thorium HTR (100 MWt) can supply the HOLCIM plant with the required energy. The optimum cycle configuration, as recommended, operates with a cycle efficiency of 42.4%
while producing 39.867 MWe. A minimum of 10 MWe can be sold to the Indian distribution
network at all times, thus generating revenue. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014
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Estudo de motor de combustão interna, do Ciclo Otto, movido a etanol previamente vaporizado / Study of Otto cycle engine fueled with prevaporized ethanolÁvila, Márcio Turra de 10 January 1994 (has links)
O etanol (álcool etílico) tem sido cada vez mais estudado e testado como combustível alternativo para substituição do uso de alguns derivados de petróleo em motores de combustão interna. O presente trabalho procura abordar o emprego do etanol na forma vaporizada em motores do ciclo Otto, objetivando a obtenção de melhores níveis de rendimento térmico total. Deste modo, um motor para teste de octanagem (motor CFR) foi equipado com um vaporizador de álcool instalado no coletor de escapamento, e após uma série de ensaios, várias análises puderam ser feitas. Essas considerações procuraram se ater a aspectos como rendimento térmico, relação ar/combustível, ângulo de avanço da centelha, temperatura de escape, assim como potência e eficiência volumétrica, levando em conta, sempre, a sua influência no funcionamento geral do motor. Ficou constatado que o motor movido a etanol vaporizado apresenta rendimento consideravelmente maior, menor consumo de combustível e funcionamento mais suave que aqueles verificados quando o mesmo motor e alimentado com álcool líquido. / The ethanol (ethyl alcohol) has been studied more and more as alternative fuel to replace some petroleum derivatives for internal combustion engines. The attached study examines the application of vaporized ethanol for Otto cycle engines, searching for better levels of total thermal efficiency. Therefore, an engine for test of octane number (CFR motor) was equipped with an alcohol vaporizer installed inside the escape pipe, and after many experiences, several analysis were made. The various analysis included aspects as thermal efficiency, air/fuel ratio, advance ignition, escape temperature, power and volumetric efficiency, always considering their influence on the operation of the engine. It was confirmed that the engine moved by vaporized ethanol presents higher thermal efficiency, smaller fuel consumption and smoother working than in case of alimentation by liquid alcohol.
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Estudo de um motor regenerativo, do ciclo Otto, movido a etanol previamente vaporizado / Study of regenerative Otto cycle engine fueled with prevaporized ethanolÁvila, Márcio Turra de 30 April 2003 (has links)
O álcool etílico ou etanol vem se tornando, neste novo século, uma importante referência para estudos e aplicações que procuram um combustível alternativo ao uso de derivados de petróleo em motores de combustão interna. Neste trabalho, o uso do etanol vaporizado pelos gases de escape em motores do ciclo Otto busca a obtenção de melhores níveis de rendimento térmico e emissões de poluentes. Assim sendo, um motor de 1.0 litro foi montado em laboratório com um trocador de calor instalado ao lado do coletor de escapamento, e uma série de testes foram feitos, possibilitando uma cuidadosa análise quanto a rendimento térmico, relação ar/álcool, ângulo de avanço da centelha, temperatura de escape e gases de emissão, entre outros aspectos. Conclui-se que o motor a álcool vaporizado, em certos regimes de funcionamento, apresenta rendimento maior e emissões menores que aqueles verificados no motor a álcool líquido. / The ethyl alcohol or ethanol is becoming, in this new century, an important reference for studies and applications that search for an alternative fuel to be used in internal combustion engines, replacing oil derivatives. In this study, an Otto cycle engine is fueled with ethanol vaporized by the exhaust gases, aiming for better levels of thermal efficiency and exhaust emissions. Therefore, a 1.0 liter engine with a heat exchanger connected to the exhaust manifold was prepared in a test bench, and several tests were made, which allowed a criterious analysis about air/alcohol ratio, spark ignition time, exhaust temperature and exhaust emissions, and others. It was concluded that the engine fueled with vaporized alcohol presents, in some operation points, higher thermal efficiency and less emissions compared to the case of engine fueled with liquid alcohol.
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Análise da eficiência térmica em conjunto habitacional: o estudo de caso Zezinho Magalhães Prado - CECAPMedeiros, Lótos Dias 11 August 2014 (has links)
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Previous issue date: 2014-08-11 / This research deals with social housing production, with an approach concerning its thermal performance. An architectural design that integrates from the beginning, Bioclimatic techniques with energy efficiency and building performance, determines a lower cost over the useful life of the building and the quality of the internal environment.
Housing Project, located in Guarulhos, São Paulo, Brazil, where the climat is subtropical and humid with annual temperatures ranging from 17ºC a 21ºC2 .
The aim of this analysis is to demonstrate the concepts applied by the architects who designed the buildings, moreover their concern with the performance of the enterprise environmental performance.
The evaluation criteria is based mainly in the following standards and certifications ABNT NBR 15575: 2013 "Building Housing - Performance," NBR 15220: 2005 "Thermal performance of buildings" and the Brazilian Certification Selo Casa Azul CAIXA" Good practices for more sustainable housing."
The obtained results demonstrate the control over the technique and the applied architectural quality as well as the evaluation of the social housing project s venture, being of great importance for the collaboration and the development of the environmental performance, applied to buildings.
The research will demonstrate the importance of standards and certifications on quality and building performance. / A presente pesquisa aborda a produção da habitação social, com viés no processo da qualidade de desempenho térmico. Um projeto arquitetônico que desde o princípio integra, técnicas Bioclimáticas com eficiência energética e desempenho do edifício, determina um menor custo ao longo da vida útil do edifício e a qualidade do ambiente interno.
O conjunto habitacional está localizado no município de Guarulhos do estado de São Paulo, que possui um clima subtropical úmido, com temperatura média anual de 17ºC a 21ºC1.
O intuito dessa análise é demostrar os conceitos que foram aplicados pelos arquitetos autores do projeto, sobretudo da preocupação e o desempenho na qualidade ambiental no empreendimento.
Tomou-se como critérios para a avaliação do desempenho térmico, as determinações das seguintes normas e certificações ABNT, NBR 15575:2013 Edificações Habitacionais Desempenho , NBR 15220:2005 Desempenho térmico de edificações e a Certificação brasileira Selo Casa Azul CAIXA Boas práticas para habitação mais sustentável .
Os resultados obtidos demostram a importância do controle sobre a técnica e a qualidade da arquitetura aplicada e avaliação nos processos de certificação dos empreendimentos de interesse social, sendo de suma importância para a colaboração e desenvolvimento do desempenho ambiental aplicado à edificação.
A pesquisa demostrará a importância das normas e certificações na qualidade e no desempenho do edifício.
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Gas utilization in Nigeria : an economic comparison of gas-to-liquid and liquefied natural gas technologies / J.E. NwankwoNwankwo, Jonathan Emeka January 2008 (has links)
Thesis (M.Eng. (Development and Management Engineering)--North-West University, Potchefstroom Campus, 2008.
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Gas utilization in Nigeria : an economic comparison of gas-to-liquid and liquefied natural gas technologies / J.E. NwankwoNwankwo, Jonathan Emeka January 2008 (has links)
Thesis (M.Eng. (Development and Management Engineering)--North-West University, Potchefstroom Campus, 2008.
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Gas utilization in Nigeria : an economic comparison of gas-to-liquid and liquefied natural gas technologies / J.E. NwankwoNwankwo, Jonathan Emeka January 2008 (has links)
Thesis (M.Eng. (Development and Management Engineering)--North-West University, Potchefstroom Campus, 2008.
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Análises de sistemas de secagem: solar, elétrico e misto na produção de banana passa. / Analysis of Drying Systems: Solar, Electric and Mixed on the production of dried banana.LIMA, Wellington Sousa. 13 June 2018 (has links)
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Previous issue date: 2017-03-17 / Este trabalho apresenta um estudo comparativo de sistemas de secagem para produção de banana passa. Foram utilizados um secador solar de exposição indireta com sistema de aquisição e controle das propriedades termodinâmicas do ar de secagem, e um secador elétrico automatizado com sistema de supervisão e controle embarcados . Os sistemas de secagem estudados neste trabalho foram: secagem solar, secagem elétrica e secagem mista (secagem solar seguida de secagem elétrica). Os testes experimentais foram realizados na UFCG em Campina Grande, PB, para secagem de banana prata (Musa spp.). O produto final obtido pelos três sistemas de secagem apresentou boa qualidade em relação ao aspecto visual,
com um percentual de umidade em base úmida menor que 25%, compatível com o recomendado pela Resolução RDC n° 272/05 da ANVISA. O sistema de aquisição e controle de dados, como inovação no secador solar, utilizando a plataforma Arduino, garantiu a medição de temperatura e umidade relativa do ar de secagem nas entradas e saídas do coletor solar e da câmara de secagem, e também o acionamento e controle da convecção forçada no sistema de secagem para manter a temperatura no interior da câmara de secagem entre 40ºC e 60ºC. Como resultado, são apresentados os valores obtidos para rendimento do secador solar, consumo específico de energia (CEE), eficiência do processo de secagem e tempo de secagem. Por meio dos experimentos com o secador solar e com o secador elétrico foram obtidas as curvas de cinética de secagem da banana. Os resultados foram comparados e mostraram que o modelo matemático de Page é apropriado para predizer o tempo de secagem. O coeficiente de determinação (R²) obtido na secagem elétrica, na secagem mista e na secagem solar com controle, foram superiores ao obtido na secagem solar sem controle, isso
demostra a importância do controle das propriedades termodinâmicas nos processos de secagem. Com relação ao CEE, o processo de secagem elétrica apresentou um CEE de 379,33 kWh por ciclo com temperatura de 45ºC e 225,54 kWh por ciclo com temperatura de 55ºC. Por outro lado o processo de secagem mista apresentou um CEE de 295,87 kWh por ciclo, a uma temperatura de 45ºC, e o processo de secagem solar apresentou um CEE médio de 45,83 kWh por ciclo. Isso mostra a grande vantagem comparativa do secador solar em relação ao secador elétrico. Com relação à eficiência mássica para os três processos de secagem, os mesmos apresentaram eficiências mássicas equivalentes em torno de 89%, o que já era
esperado. Com relação aos rendimentos térmicos do secador solar, obtidos nos processos de secagem solar com controle e sem controle da temperatura , foram respectivamente 27,85% e 30,65%. Esses resultados são ligeiramente maiores que os reportados na literatura, o que indica que o secador solar desenvolvido na UFCG apresenta um elevado padrão na secagem de banana, além do fácil manuseio, construção e operacionalidade. / This paper presents a comparative study of drying systems for the production of dried bananas. An indirect solar exposure dryer with acquisition system and control of the thermodinamic properties of the drying air, and an automatized electric dryer with embedded control and supervision system were used. The drying systems studied in this paper were: solar drying, electrical drying and mixed drying (solar drying followed by electrical drying). The experimental tests were performed at the UFCG in Campina Grande, PB, for the drying of bananas (Musa spp.). The final product obtained by the three drying systems presented good visual aspect, scent and flavour, and moisture percentage at moist base less than 25%, compatible to the resolution RDC nº 272/05 of the ANVISA. The acquisition system a nd data control, added as inovation at the solar dryer, using the Arduino plataform, granted the measurement of the temperature and air relative moisture of drying air, both in the entrance and exit of the solar colector of the drying chamber, and also the activation and control of the forced convection of the drying system to keep the temperature in the drying chamber between 40ºC and 60ºC. As results, the obtained values to the drying system efficiency are presented, specific comsuption of energy (CEE), drying system efficiency and drying time. Through the experiments with the solar and the electric dryers, the curves that represent the
drying kinectics of the banana were obtained. The results were compared and showed that Page’s mathematical model is adequate to predict the drying time. The determination coefficient (R²) obtained at the electric dryer was superior to the solar dryer, this shows that the control system of the thermodinamics properties of the drying air is more efficient on the electric dryer. In relation to the CEE, the electric drying showed a CEE of 379.33 kWh per cycle with a temperature of 45ºC and 225.54 kWh per cycle at the temperature of 55ºC . On the other hand, the mixed drying had a CEE of 295.87 kWh per cycle, at a temperature of 45 ºC, and the solar drying a medium CEE of 45.83 kWh per cycle. This shows the great comparative advantage of the solar dryer when compared to the electric dryer. In relation to the massic efficiency to the 3 drying processes, they showed equivalente massi c efficiency around 89%, which was expected. In relation to the thermic efficiencies of the solar dryer, obtained on the experiments with and without temperature control, were respectively 27.85%, 30.65%, these results show that the obtained resulsts are slightly superior to the results
reported on the literature, which indicates that the solar dryer under development in the UFCG shows high efficiency to perform the drying of bananas, although its easy to construct and operate.
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Construção e avaliação térmica de um sistema concentrador parabólico com seguidor solar / Construction and evaluation of a parabolic concentrator with solar trackerOliveira Junior, Gilberto Bueno de [UNESP] 18 December 2015 (has links)
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Previous issue date: 2015-12-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The searching for renewable energy sources has mobilized much of the scientific community, which work is tireless in pointing out feasible solutions to use clean energy. Solar energy is natural choice among others, because its availability and amount. A known way to use this energy is by focusing solar rays through parabolics, which allow rays concentration to a small area. The advantage of this type of project is to produce thermal energy at high temperatures. This energy has a wide application on producing other forms of energy such as electric power in turbines since solar concentrators provide steam at high pressure and temperature. The goal of this study is to build a solar concentration device and measure the energy produced, as well its efficiency in transformation. Thus, was built up a parabolic concentrator and a solar tracker to motion in three dimension, which allows device alignment towards incidence of solar rays. Was utilized a pumping system to flowing thermal fluid at high temperatures through the absorber. The energy balance of this thermal fluid, led to obtain behavior curves of net power and system efficiency. The experimental was divided in two parts. On the first one, was obtained the stagnation temperature and the other one, was measured the eficiency over a circulating thermal fluid. The stagnation temperature measured in december was 476,5°C, at 4:25PM. The second part of tests has shown an efficiency of 33% on first one assay. However when was utilizing another form to measure the solar irradiation (theoretic approach), the efficiency rises between 45% to 55%, regarding steady state conditions. Furthermore, this work allowed discussions to discover ways to increase the energy efficiency. / A busca por formas alternativas de energia tem mobilizado grande parte da comunidade científica, cujos trabalhos são incansáveis em apontar soluções viáveis para o aproveitamento das energias renováveis e limpas. A energia solar se destaca dentre todas pela sua disposição e quantidade. Uma forma já conhecida de sua utilização é através da concentração em sistemas parabólicos, que permitem o direcionamento dos raios do Sol para uma pequena área. A vantagem deste tipo de projeto é a produção de energia térmica a altas temperaturas e pressões. Essa energia concentrada possui grande aplicação, pois permite a conversão eficiente em energia elétrica, produzidas em turbinas a vapor. O objetivo deste trabalho foi construir um dispositivo termo-eletrônico para concentração solar e, com isso, quantificar a energia produzida, bem como sua eficiência. Assim sendo, foi construído um concentrador parabólico e um rastreador solar com movimento tridimensional, que permite o alinhamento do equipamento com a incidência dos raios do Sol. Foi utilizado ainda, para circulação no interior do absorvedor, um sistema de bombeamento de fluido térmico de alto ponto de ebulição e que não sofria deformação a altas temperaturas. O balanço energético no dispositivo permitiu obter as curvas de potência útil e da eficiência do sistema. O experimento foi dividido em duas partes. Na primeira parte, foi obtida a temperatura de estagnação e na outra parte, foi medida a eficiência energética sobre o fluido térmico em circulação. A temperatura de estagnação medida em dezembro foi de 476,5 °C, às 4:25 PM. A segunda parte dos testes mostrou uma eficiência de 33% no primeiro ensaio. No entanto, quando se utilizou uma outra forma de medir a irradiação solar (abordagem teórica), a eficiência aumentou, permanecendo entre 45% a 55%, considerando regime permanente. Além disso, possibilitou a discussão de formas de incrementar a sua eficiência. / Capes: 2012/2014
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