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1
Lee, Hi Sun. "Spray generation by gas-lift pumps". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61897.
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2
Opseth, Douglas A. "Landfill gas generation at a semi-arid landfill". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq39150.pdf.
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Witty, Susan Jean. "Sound generation by gas flow through corrugated pipes". Thesis, University of Hull, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395653.
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4
Eccles, Neil C. "Structured grid generation for gas turbine combustion systems". Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/7348.
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Commercial pressures to reduce time-scales encourage innovation in the design and analysis cycle of gas turbine combustion systems. The migration of Computational Fluid Dynamics (CFD) from the purview of the specialist into a routine analysis tool is crucial to achieve these reductions and forms the focus of this research. Two significant challenges were identified: reducing the time-scale for creating and solving a CFD prediction and reducing the level of expertise required to perform a prediction. The commercial pressure for the rapid production of CFD predictions, coupled with the desire to reduce the risk associated with adopting a new technology led, following a review of available techniques, to the identification of structured grids as the current optimum methodology. It was decided that the task of geometry definition would be entirely performed within commercial Computer Aided Design (CAD) systems. A critical success factor for this research was the adoption of solid models for the geometry representation. Solids ensure consistency, and accuracy, whilst eliminating the need for the designer to undertake difficult, and time consuming, geometry repair operations. The versatility of parametric CAD systems were investigated on the complex geometry of a combustion system and found to be useful in reducing the overhead in altering the geometry for a CFD prediction. Accurate and robust transfer between CAD and CFD systems was achieved by the use of direct translators. Restricting the geometry definition to solid models allowed a novel two stage grid generator to be developed. In stage one an initial algebraic grid is created. This reduces user interaction to a minimum, by the employment of a series of logical rules based on the solid model to fill in any missing grid boundary condition data. In stage two the quality of the grid is improved by redistributing nodes using elliptical partial differential equations. A unique approach of improving grid quality by simultaneously smoothing both internal and surface grids was implemented. The smoothing operation was responsible for quality, and therefore reduced the level of grid generation expertise required. The successful validation of this research was demonstrated using several test cases including a CFD prediction of a complete combustion system.
5
Papadopoulos, Tilemachos. "Gas turbine cycles for intermediate load power generation". Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/10718.
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The
objective of this thesis is to determine if an advanced gas turbine cycle exists,
which can
compete with the simple and the combined cycles in the intermediate load
electricity generation market; defined as the market with annual utilisation between
3,000 to 6,000 operating hours.
Several
thermodynamic cycles in the 100MW and 200MW power output range are
investigated and compared to base reference simple and combined cycles that have
been defined
by a survey of existing models in the market.
For the
investigation of these cycles, gt-ETA (gas turbine - Economic and Technical
Analysis) has been developed; a software for the design and off-design
thermodynamic performance and the economic evaluation of gas turbine cycles.
A new method is
proposed for calculating the total capital investment of a advanced
cycle engine project. This is based on deriving empirical relations linking the
purchased equipment cost to power output and thermal efficiency, based on published
data for
simple cycle engines. Standardised values are used for the specific costs of
different
performance improvement' packages.
A
optimisation process is developed for the determination of the optimum split
between the
capital investment of a baseline' simple cycle engine and a 'performance
improvement package.
For accurate
performance calculations a cooling air model has been created based on
either the direct definition of
cooling air amounts or the required hot gas path
component metal temperatures. The model is able to select the optimum cooling
configuration considering the temperature and pressure of mixing streams.
The advanced
cycles are competitive against base reference cycles only in the power
range of l00MW. From the configurations considered, the recuperated cycle with
spray intercooling seems to be the most promising option with a wide range of
competitiveness at both design and off-design operating conditions and along the
sensitivity range of changing fuel prices.
6
Uvwie, Patrick Awaciere. "Nigeria's gas flaring reduction : economic viability of power generation using flared gas / P.A. Uvwie". Thesis, North-West University, 2008. http://hdl.handle.net/10394/3697.
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Hayko, Robert Kory. "Systems approach to natural gas analysis for power generation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ30858.pdf.
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Tsoutsanis, Elias. "Performance adaptation of gas turbines for power generation applications". Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5614.
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One of the greatest challenges that the world is facing is that of providing everyone access to safe and clean energy supplies. Since the liberalization of the electricity market in the UK during the 1990s many combined cycle gas turbine (CCGT) power plants have been developed as these plants are more energy efficient and friendlier to the environment. The core component in a combined cycle plant is the gas turbine. In this project the MEA’s Pulrose Power Station CCGT plant is under investigation. This plant cronsists of two aeroderivative LM2500+ gas turbines of General Electric for producing a total of 84MW power in a combined cycle configuration. Cont/d.
9
Grilli, Roberto. "Methods for Trace Gas Detection Using Difference Frequency Generation". Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520211.
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AVELLAR, VINICIUS PIMENTA DE. "TRANSIENT MODELLING OF INDUSTRIAL GAS TURBINE FOR POWER GENERATION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16332@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROAs turbinas a gás são equipamentos de vital importância para o setor industrial, fornecendo trabalho e calor para diversos setores, do transporte aos sistemas de cogeração. A crescente necessidade de geração de energia elétrica confiável tem incentivado o projeto de turbinas a gás industriais, inclusive no Brasil, que operam com vários combustíveis como o diesel, gás natural, álcool e de combustíveis de baixo poder calorífico. Para melhor monitorar e controlar estes motores, uma análise completa da previsão de funcionamento em regime transitório é necessária. Durante o regime transitório das turbinas a gás industriais (heavy-duty), o sistema de controle deve manter os limites de certos parâmetros, tais como a temperatura na entrada da turbina e a velocidade de rotação do eixo, no seu valor nominal. Além disso, o tempo de resposta necessário para o sistema de controle atuar deve ser o mais breve possível para garantir uma operação de qualidade, segura e confiável. A temperatura de entrada da turbina, que é um parâmetro muito importante no desempenho de uma turbina a gás, é limitada pela resistência mecânica do material das pás da turbina. A velocidade de rotação do eixo deve permanecer constante, devido à ligação ao sistema elétrico, que não pode suportar altas flutuações de freqüência. Este trabalho tem como motivação o incremento da capacidade de simulação de um modelo computacional existente, incorporando, para este fim, rotinas de sistemas de controle. Como resultado, o novo modelo é capaz de simular qualquer condição de funcionamento de turbinas a gás industriais, em regime permanente e transitório controlado. Os resultados obtidos pelo programa computacional se mostraram fiéis ao comportamento real da máquina. Além disso, mostraram a flexibilidade do modelo ao lidar com diferentes condições de operação.Um programa computacional capaz de simular o desempenho transitório controlado de turbinas a gás é de extrema relevância para o desenvolvimento de softwares que auxiliam os operadores destes equipamentos. Dentre estes, estão os sistemas de monitoramento e diagnóstico dos equipamentos em questão.
Gas turbine engines are a vital part of today’s industry, providing both work and heat for several industry sectors, from transportation to cogeneration systems. The growing need for reliable electricity has encouraged the design of stationary gas turbines, including in Brazil, which operates on multiple fuels such as diesel, natural gas and low calorific fuels. To better monitor and control these engines, a complete analysis for prediction of transient operation is required. During transient operation of heavy duty gas turbines, the control system must keep the limits of certain parameters, such as turbine inlet temperature (TIT) and the rotational shaft speed within their design range. Moreover, the time required for the control system to react should be as short as possible to guarantee a safe and reliable operation. The turbine inlet temperature, which is a very important parameter in the performance of a gas turbine, is limited by the turbine blades material mechanical resistance. Furthermore, the rotational speed should remain constant due to the electric grid connection, which cannot withstand high frequency fluctuations. This work is motivated by the need to increase the ability of a computer model to simulate the performance of industrial gas turbines, incorporating, for this purpose, control system routines. As a result, the new model will be able to simulate any operating condition of industrial gas turbines, in both steady state and transient. The results obtained by the computer program proved to be faithful to the actual behavior of the engine. Furthermore, they showed the flexibility of the model to deal with different operating conditions. A computer program capable of simulating the transient performance of gas turbines is very important for the development softwares to help operators of such equipment. In addition, it could be used in on-line intelligent diagnostic program.
11
Taconi, Katherine Ann. "Methanogenic generation of biogas from synthesis-gas fermentation wastewaters". Diss., Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-07072004-085409.
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12
Zahid, Amna. "Aspects of Attosecond Pulse Generation Through High-Harmonic Generation". Thesis, Griffith University, 2018. http://hdl.handle.net/10072/376728.
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We systematically optimize the yield of XUV pulses at 93 2 eV with respect to
experimentally adjustable parameters such as gas pressure, focal position of laser
beam and interaction length by using few cycle laser pulses. We demonstrate
carrier-envelope phase dependence of the optimized XUV spectrum, consistent
with the formation of isolated attosecond pulses. We present the progress to-
wards a newly developed attosecond beamline and describe its essential parts in
detail. We perform initial experiments on photoelectrons detection. This work
will contribute further for optimizing the setup for attosecond streaking experiments.Thesis (Masters)
Master of Philosophy (MPhil)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
13
Abdela, Ahmed. "Gas phase generation and deposition of size-selected metal clusters". Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4955/.
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This thesis presents modifications to and optimisations of a cluster beam source, one application being the generation of large area catalysis samples. A major modification to the cluster source also enabled coating of clusters in a new way. The impact of Pd\(_5\)\(_6\)\(_1\), Pd\(_5\)\(_5\)and Pd\(_4\) clusters (1, 1.5 and 1 keV) on a thin material film evaporated onto a solid argon matrix led to deposition of large, 5-40 nm diameter, irregularly shaped particles. Furthermore, Pd\(_9\)\(_2\)\(_3\) and Pd\(_2\)\(_0\)\(_0\)\(_0\) clusters, with both 0.5 and 1.5 keV impact energies, have been coated in-flight by impact on the thin film/solid matrix, as verified from the increase in diameters of the deposited particles and the detection of Pd signal by EELS. MoS\(_2\) nano pillar catalyst samples were etched using size-selected metal etch masks. Catalyst samples of ordered MoS\(_2\) nano pillars were fabricated using NSL and a novel way to apply nano spheres was developed. Different etch recipes were used to obtain nano pillars with different diameters and heights; these recipes were also applied to reference MoS\(_2\) samples without etch masks. Generally, the reference catalyst samples, with their roughened surfaces, showed higher HER activity than their corresponding ordered MoS2 nano pillar catalyst samples.
14
Bellgren, Sofia, i Isabel Sondén. "Coupling of Nuclear Power Generation with Greenhouse Gas Capture Technology". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297557.
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In order to stop the escalating global warming, humankind rapidly needs to develop and implement technology to lower the level of carbon dioxide in the atmosphere. Today there are methods to capture CO2 directly from the atmosphere (DAC); the problem lies in how to power them in a fossil-free and cost-attractive way. This report will focus on the application of thermal waste energy from nuclear power for DAC. To enable the coupling of the power plant to the DAC, the thermal waste energy i. e. low-pressure steam from the plant's thermal cycle, has to be brought to a higher temperature and pressure. Improving the steam can be done using one or multiple ejectors, and they can connect in different configurations. In this study, we vary the ejector configuration and the geometric parameters of the ejectors to optimize the performance of the setup. We show that three ejectors are preferable to reach the goal of 1-2 bar and that other configurations might be valuable when lowering the pressure limit.
15
Xiao, Hua. "Combustion of green fuels for power generation in gas turbine". Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/111951/.
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The main objective of this thesis is to investigate the fundamental combustion process of ammonia-based fuels and the application on swirl-stabilised flames in the context of engineering type gas turbine combustion. The present study begins with a fundamental validation and mechanism reduction for chemical kinetics of ammonia/methane combustion. Different-sized reduced mechanisms of the well-known Konnov’s mechanism were compared at high-pressure conditions relevant to gas turbine devices. The reduced models can benefit the future simulation work with considerably less computational cost. Then characteristics of ignition delay time, laminar flame speed and emissions were obtained over a wide range of equivalence ratios and ammonia fractions. Prediction results showed a good potential of ammonia/methane to be used in gas turbine engines with relatively low emission. In the second part of this dissertation, in order to identify reaction mechanisms that can accurately represent ammonia/hydrogen kinetics at industrial conditions, various mechanisms were tested in terms of flame speed, combustion products and ignition delay against experimental data. It was preliminarily found that the Mathieu mechanism and Tian mechanism are the best suited for ammonia/hydrogen combustion chemistry under practical industrial conditions. Based on the Mathieu mechanism, an improved chemical mechanism was developed. Verification of the established model was quite satisfying, focusing particularly on elevated conditions which are encountered during gas turbine operation. Finally, a first assessment of the suitability of a chosen 70%NH3-30%H2 (%vol) blend was performed for utilisation within a gas turbine environment. It was found that stable flames can be produced with low NOx emissions at high equivalence ratios. Also, results showed that high inlet temperature conditions representative of real gas turbine conditions can significantly improve the combustion efficiency and reduce NOx emissions. A numerical gas turbine cycle calculation was performed indicating more research are required to enable higher efficiencies using ammonia/hydrogen.
16
SanGiorgio, Paul. "Measuring Electron Gas Relaxation in Gold through Second Harmonic Generation". Scholarship @ Claremont, 2001. https://scholarship.claremont.edu/hmc_theses/136.
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In a thermally equilibrated system, electron behavior in a metal is described by the Fermi-Dirac equation. With ultrafast lasers, electrons can be excited into temporary distributions which are not described by the Fermi-Dirac equation and are therefore not at a well-defined temperature. These nonthermal distributions quickly equilibrate through two primary processes: electron-electron scattering and electron-phonon scattering. In most situations, these effects are unnoticeable, since they are completed within 5 ps. A probabilistic numerical model for electron-electron scattering is presented. The model is robust, scaleable, and requires only one parameter. The success of the model suggests future work on a similar electron-phonon scattering model, which would provide a complete description of the elctron distribution during thermalization. Once complete, this model can be tested by measuring the amount of second harmonic light generated by an ultrafast laser in a pump-probe experiment.
17
Sinclair, Bruce David. "Second harmonic generation in sodium vapour induced by a magnetic field". Thesis, University of St Andrews, 1987. http://hdl.handle.net/10023/13925.
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A high resolution study of magnetic-field-induced second harmonic generation in sodium vapour was performed using a single-frequency continuous-wave dye laser. Resonant enhancement was obtained by tuning the laser to the frequency of the 3S-40 two-photon transition of the sodium atoms. Coherent parametric emission of the second harmonic radiation ocurred in the presence of a symmetry-breaking magnetic field by means of a coherent electric-quadrupole emission at twice the laser frequency. A theoretical model of the second harmonic generation (SHG) was developed, and includes the roles played by atomic selection rules, Zeeman splitting and eigen function mixing in a magnetic field, and the effects of homogeneous and inhomogeneous broadening. The use of a single-frequency laser and an atomic nonlinear medium allowed an experimental investigation of a SHG process in unprecedented detail. This provided astringent test of the theoretical model developed to predict the properties of the nonlinear interaction in terms of fundamental atomic parameters. The excellent agreement obtained between theoretical and experimental results vindicated the theoretical methods used in the modelling.
18
Bortot, Baptiste. "Gas for Balancing of Variable Power Generation : A Systemic Case Study". Thesis, KTH, Elektriska energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144860.
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With the increasing share of variable renewable generation, balancing electric powersystems could become a major concern for system operators because of their variableand hardly predictable nature. However, gas technologies appear as a solutionto provide this flexibility, but the impacts on the gas power system have hardly beeninvestigated. In this thesis, consulting reports on the subject matter, regulator suggestions andgas-electricity interaction models in scientific literature are studied and four sourcesare identified to be used for balancing: linepack, storage facilities, liquefied natural gasand intraday gas supply from adjacent areas. Then, a gas-electricity model for flexibility supply is designed and three case studies are simulated in order to analyze bothgas and electric power systems’ behaviors. In these case studies, electricity generation,contribution of gas sources and costs are analysed. The study concludes that critical situations on gas market that can occur, e.g. incases of large variation in the net electricity demand and limited availability of linepackand storage facilities, the need of intraday modulation can exceed the possibilities toprovide for it. Then, gas cannot be supplied to power plants during peak periods, andmore gas than necessary is used during off-peak periods. The case studies also showthat day-ahead forecast errors in variable renewable generation can be handled mucheasier than variations by the gas system but leads to higher costs.
19
Gibrael, Nemir, i Hamse Hassan. "HYDROGEN-FIRED GAS TURBINE FOR POWER GENERATION WITH EXHAUST GAS RECIRCULATION : Emission and economic evaluation of pure hydrogen compare to natural gas". Thesis, Mälardalens högskola, Framtidens energi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-42306.
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The member states of European Union aim to promote the reduction of harmful emissions. Emissions from combustion processes cause effects on human health and pose environmental issues, for example by increasing greenhouse effect. There are two ways to reduce emissions; one is to promote renewable energy sources and the other to utilize more effectively the available fossil fuels until a long-term solution is available. Hence, it is necessary to strive for CO2 mitigation technologies applied to fossil fuels. Low natural gas prices together with high energy efficiency have made gas turbines popular in the energy market. But, gas turbine fired with natural gas come along with emissions of CO2, NOx and CO. However, these disadvantages can be eliminated by using gas turbine with precombustion CO2 capture, separating carbon from the fuel by using fuel reforming process and feeding pure hydrogen as a fuel. Hydrogen fired gas turbines are used in two applications such as a gas turbine with pre-combustion CO2 capture and for renewable power plants where hydrogen is stored in case as a backup plan. Although the CO2 emissions are reduced in a hydrogen fired gas turbine with a pre-combustion CO2 capture, there are still several challenges such as high flame temperatures resulting in production of thermal NOx. This project suggests a method for application of hydrogen fired gas turbine, using exhaust gas recirculation to reduce flame temperature and thus reducing thermal NOx. A NOx emission model for a hydrogen-fired gas turbine was built from literature data and used to select the best operating conditions for the plant. In addition, the economic benefits of switching from natural gas to pure hydrogen are reported. For the techno-economic analysis, investment costs and operating costs were taken from the literature, and an economic model was developed. To provide sensitivity analysis for the techno-economic calculation, three cases were studied. Literature review was carried out on several journal articles and websites to gain understanding on hydrogen and natural gas fired gas turbines. Results showed that, in the current state, pure hydrogen has high delivery cost both in the US and Europe. While it’s easy to access natural gas at low cost, therefore in the current state gas turbine fired with natural gas are more profitable than hydrogen fired gas turbine. But, if targeted hydrogen prices are reached while fuel reforming process technology are developed in the coming future the hydrogen fired gas turbine will compete seriously with natural gas.
20
Bahamón, García Daniel. "New generation adsorbents for gas separation: from modeling to industrial application". Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/325690.
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Teniendo en cuenta el rápido aumento de la población y el crecimiento en el consumo de energía como consecuencia de grandes progresos en transporte y tecnología, el desarrollo sostenible es de especial relevancia pues sugiere la búsqueda de formas de mitigar las emisiones de gases de efecto invernadero, incluyendo la captura y almacenamiento de carbono (o utilización), la eficiencia energética, fuentes alternativas de energía y ahorro de energía, como ya se ha sugerido por el protocolo de Kioto y los informes del IPCC. De ahí que en los últimos años se haya dedicado un esfuerzo considerable a desarrollar tecnologías para la captura y almacenamiento de CO2 a partir de fuentes concentradas de emisión.
Además de establecer nuevas tecnologías, durante las últimas décadas la ciencia de materiales sólidos porosos se ha convertido en una de las áreas más intensas de investigación y desarrollo para químicos, físicos y científicos de materiales. De hecho, se ha avanzado considerablemente en el desarrollo de nuevos adsorbentes para diversos procesos de separación. Por ejemplo, las estructuras órgano-metálicas (MOFs) han ido ganando considerable atención como materiales prometedores para aplicaciones de almacenamiento y separación de gases, debido a sus propiedades excepcionales. Sin embargo, es necesaria una comprensión a nivel molecular de la adsorción de gases para acelerar el diseño y desarrollo de aplicaciones a la carta. También es fundamental conocer el comportamiento bajo condiciones de humedad e impurezas, como se tiene normalmente en aplicaciones industriales específicas.
El trabajo desarrollado en esta Tesis Doctoral destaca el uso de técnicas de simulación molecular para la optimización de procesos relacionados con el medio ambiente. El objetivo general se centra en avanzar en el campo de materiales para la captura y separación de dióxido de carbono a condiciones de proceso. Se considera de manera explícita la influencia del vapor de agua e impurezas, tanto a la luz de los fundamentos de la adsorción como en la aplicación para la captura de CO2 por post-combustión mediante ciclos de adsorción por oscilación.
Partiendo de una breve descripción de los fundamentos de la adsorción y de las simulaciones moleculares, se presenta una revisión exhaustiva de estudios recientes de materiales para captura y separación de CO2, proporcionando así información valiosa para su aplicación industrial. Basados en esta revisión, se han estudiado en detalle algunos de los materiales más prometedores para un proceso de adsorción por cambio de temperatura (TSA) basado en simulaciones moleculares, proponiéndose un nuevo procedimiento para la evaluación y optimización de los sistemas de captura en condiciones reales. Dada la gran influencia de trazas de agua en la separación, se investiga también el CuBTC (uno de los MOF más estudiados y estables en agua) en comparación con la zeolita de referencia 13X. Se examina en detalle el efecto de las especies coexistentes, así como la influencia del agua y SO2 en los gases de combustión, con el fin de llegar a una mejor comprensión de la capacidad de adsorción, la selectividad, la localización de las moléculas en el material, las distribuciones de calor isostérico y su relación con el proceso.
Asimismo, se han llevado a cabo estudios paramétricos detallados para una investigación comparativa de la separación de mezclas multi-componentes de gases de combustión mediante el uso de otras zeolitas como caolinita y chabacita. Y finalmente, se presenta un trabajo adicional relacionado con otro problema medioambiental: la separación de un contaminante (ibuprofeno) en agua, mediante el uso de carbones activados, usando las mismas técnicas computacionales, demostrando así la versatilidad de las herramientas empleadas para este tipo de sistemas.Given the rapid increase in population and the growth in energy consumption as a consequence of major developments in transportation and technology, sustainable development is of special relevance, suggesting ways to mitigate greenhouse gases emissions, including carbon capture and storage (or utilization, CCSU), energy efficiency, alternative energy sources and energy savings, as already suggested by the Kyoto’s Protocol and the IPCC reports. Hence, much effort has been devoted in recent years to develop technologies for capture and storage of CO2 from concentrated sources of emission. Apart from establishing new technologies, over the last decades the science of porous solid materials has become one of the most intense areas of research and development for chemists, physicists, and materials scientists. In fact, considerable progress has been made in recent years on the development of novel adsorbents. For instance, Metal Organic Frameworks (MOFs) have been gaining considerable attention as promising nanoporous materials for gas storage and gas separation applications due to their exceptional physical and chemical properties, and have already been demonstrated to be promising materials in the separation of different gases, however, a molecular level understanding of gas adsorption in the pores is crucial to accelerate the design and development of these and other applications. It is also fundamental to know their behavior under moisture conditions and impurities content, as normally found at specific industrial applications. The work developed in this Thesis highlights the use of molecular simulation techniques for optimizing environmental related processes, providing new procedures to assess the use of these materials from their fundamental knowledge until their applications at industrial conditions. The overall objective is to advance in the field of materials for CO2 capture and separation at process conditions. The influence of water vapor and impurities is explicitly considered, both, in the light of the fundamentals of adsorption and in the application for post-combustion carbon dioxide capture by swing adsorption cycles. Starting from a brief description of the fundamentals of adsorption and molecular simulations, a novel throughout review on recent studies of materials for CO2 capture and separation is presented, thus providing valuable information to assess their industrial application. Based on this review, some of the most promising materials for CO2 separation in a Temperature Swing Adsorption (TSA) process have been studied in detail by using molecular simulations (compared to experimental data when available), proposing a new process for the evaluation and optimization capture systems under real conditions. In addition, given the great influence of water as a trace compound on the separation, CuBTC (one of the most studied MOFs, stable in water and with potential for industrial application) has been investigated in comparison to the benchmark zeolite 13X. The effect of the coexisting species as well as the influence of water and SO2 in flue gas is examined in detail in order to reach a better understanding of the adsorption capacity, selectivity, adsorption density location and isosteric heat distributions. And finally, detailed parametric studies have been carried out for a comparative computational investigation for separating of multi-component mixtures of flue gas by using other representative zeolites such as kaolinite and chabazite. Additional work, related to another environmental problem: the separation of a pollutant (ibuprofen) in water, by using activated carbons, is also presented here, demonstrating the versatility of the tools used for these types of systems.
21
Atse, Jean-Philippe. "A new generation of multilateral well enhances small gas field economics". Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/353.
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The main objective of this study is to investigate the applicability of a new multilateral well architecture in the domain of small size and offshore gas fields. The new architecture completely reverses the current multilateral technology. The innovative concept suggests that laterals can be achieved like any conventional wells. They could be drilled from the surface and tied back to a common wellbore referred to as the mother well. Production would go through the toe of laterals into the mother well. The mother well could be as simple as a large diameter casing equipped with prepared connections to tie in feeder wells. This study looked past the mechanical challenge of achieving the new architecture. I demonstrated important benefits in terms of cost reduction, well completion and operations, and reservoir drainage. I looked at a typical field case, Phoenix, located in West Africa. Its actual development plan targets an ultimate recovery of 600 BCF with a total of four sub-vertical wells. I implemented a new development scenario with the innovative multilateral architecture. For comparison purposes, I achieved a reservoir simulation and a production forecast with both scenarios. The only simulation variable was the well architecture definition. As a main result, the new multilateral structure could produce as many as four vertical wells with three slim-hole laterals. I achieved a quantitative risk analysis on both development plans. I assessed the development cost of each scenario and performed a Monte Carlo simulation to account for cost uncertainties. In addition to the actual 70 MMSCFD gas contract, I simulated a progressive gas demand increase of 20 MMSCFD every five years and a 150 MMSCFD gas market. The study demonstrates the economic benefits of the new technology in the domain of offshore and small gas fields. This work also shows that this new generation of multilaterals brings new option values to the domain of multilateral technology.
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Seymore, Sean Bernard. "Studies pertaining to the mechanisms of gas generation in nuclear waste". Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/27615.
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McCaughey, Conor Michael. "The solidification of niobium silicides for next generation gas turbine engines". Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/17589/.
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Nickerson, Ian James Carleton University Dissertation Engineering Mechanical and Aerospace. "A parametric study of gas turbine cycles for electrical power generation". Ottawa, 1994.
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Ben, Hariz Houssein. "The optimisation of the usage of gas turbine generation sets for oil and gas production using genetic algorithms". Thesis, Cranfield University, 2010. http://hdl.handle.net/1826/4479.
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The privatisations of the energy supply industries world-wide has meant that emphasis is now on how to profitably compete. In this environment the development of effective models for optimisation of power plant are of increasing importance, particularly operational strategies for off-design conditions, and particularly for gas turbine engines.
Maximisation of plant profitability necessitates proper and integrated evaluation of many factors, the most important of which are: availability and price of fuel, system efficiency and performance, life cycle costing of plant and machinery, present and future generation of revenue, likely future market dynamics.
A major contribution of this work is the application of the proposed method to simultaneously maximise both total profit and usage availability of a typical combination of gas turbines engines used for power generation in oil and gas production. The method allows the user, for example, the opportunity to select locally appropriate daily and seasonal power demands and ambient conditions.
Through a genetic algorithm optimisation technique, an additional powerful feature of the method is that it allows the user to choose an optimised operating combination of their existing gas turbine equipment. Both individual engine power setting and number of engines can be varied. Alternatively, the user can apply the code to select the best combination of new and/or replacement equipment to achieve best economic performance and highest availability.
The number of variables involved in the optimisation process is, of course, very large. It is, therefore, difficult to find the optimal configuration. To address this problem, the first phase of this study is limited to the analysis of the performance of industrial gas turbine engines. The primary aim is to identify the key parameters in the determination of off-design performance. The second aim for the first phase is to identify those tasks suitable for automation. The Gas Turbine Library (Turbomatch) developed at Cranfield University includes simulation
codes for many different industrial gas turbines and processes. The optimiser developed as part of this research has been linked with that library.
The second phase of this project is to develop an economic model for gas turbines analysing off-design performance. The model includes a life cycle cost assessment including: capital cost, maintenance and operating costs, fuel cost, emission and other taxes and disposal cost. By including total revenue it has been possible to develop a model that allows maximisation of total profit under variable operating conditions.
The third phase of the project presents an automated optimisation tool based on a listing of the Turbomatch simulation code and a genetic algorithm technique. The tool uses an evaluation of the fitness value of the objective function and takes into account the optimisation constraints. Two case studies considered where real data obtained from oil field in Libya are used to illustrate the use of the new code to maximising the profit.
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Yan, Binghua. "Enhanced methane gas generation by reutilization of acidogenic off-gas during two-phase anaerobic digestion of food waste". HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/160.
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Mass balance analysis of two-phase AD indicated that off-gas (H2 and CO2) produced in acidogenic reactor represent up to 30% of the consumed substrate and under most circumstances, this part of energy was not utilized leading to low overall energy recovery. Hence, the objective of this study was to enhance overall energy recovery during two-phase AD of food waste through reutilization of acidogenic off-gas and to further optimize the processes through manipulating the metabolic pathways and controlling acidogenic off-gas production. In the first phase, feasibility of reutilizing acidogenic off-gas in methanogenic reactor and contribution of acidogenic off-gas to overall energy recovery was investigated. Acidogenic off-gas diversion increased the methane gas (CH4, 0.28 L/g VSadded) production up to 38.6%, of which ~8% was contributed by acidogenic off-gas. Both higher hydrolysis rate and COD production were also achieved with off-gas diversion. Metabolic pathway determines the distributions of intermediate soluble products, which constitute the quality of acidogenic leachate. Therefore, two experiments focusing on manipulating metabolic pathways were performed. Firstly, the effects of four levels of headspace pressures, 6-12 psi (T1), ~3-6 psi (T2), ~3 psi (T3) and ambient pressure (T4) were investigated. Mixed acids metabolic pathways prevailed in all the treatments with butyrate as the single major component. Then, four different levels of H2 partial pressure (PH2) were set the next experiment, self-generated PH2 (T1, control), 80% of H2 (T2), 60% of H2 (T3) and 0.04% of H2, while the headspace pressure was kept at 3.3 psi. Typical butyrate fermentation pathways dominated in T4 whereas mixed acid fermentation pathways were prevailing in the other three treatments. Because of the improved hydrolysis/acidogenesis and higher quality of acidogenic products, overall CH4 recovery in T4 (301.0 L/kg VSadded) was 44.6% higher than the control. In Phase III, strategies to enhance acidogenic off-gas production were investigated. First, four types of neutralization modes including daily pH adjustment of leachate to 6.0, methanogenic effluent recirculation, and initial addition of NaOH and lime separately at a dosage of 20.0 and 14.0 g/kg food waste, respectively, were investigated. Obviously, a H2 production rate of 3.0 and 2.1 L/d with lime and NaOH addition was much higher than 0.7 and 0.4 L/d with effluent recirculation and daily adjustment, respectively. Also, addition of alkali agents could enhance the COD leaching of food waste, especially with NaOH. A CH4 production of 11.24 L/d could be attributed to both the elevated leachate quality and the acidogenic off-gas with lime addition. Another experiment investigated the effect of different carbohydrate contents in the substrates on acidogenic H2 production. Anaerobic hydrolysis of wastes sourced from bakery (T1), Chinese-style restaurant (T2), western-style restaurant (T3) and wet market were performed in LBRs. Food waste collected from western-style restaurant with a carbohydrate content of 69.5% achieved the highest H2 production of 61.0 L/kg VSadded. The highest specific CH4 production rate at 0.42 L/gVSadded was also achieved with western restaurant food waste. Finally, the possible redirection of fluxes associated with shift of metabolic pathways from the experiment of PH2 was proposed. Significant increase in the production of butyrate in treatment T4 with PH2 of 3.3 psi × 0.04% indicated the channeling of electrons towards the production of butyrate. Dynamics of the microbial community were correlated with the distribution of metabolites. In T1 without external gas flushing, lactic acid fermentation was dominant during the initial 7-days. Accordingly, phylotypes affiliated to the genus Lactobacillus sp. were detected. A heterlatic fermentation pathway was observed in in both T2 and T4 during first four days, and thereafter the fermentation pathways shifted towards acetate and butyrate as dominant products, which were accompanied by changing the microbial community with phylotypes of Clostridium sp. and Bifidobacterium sp. becoming dominant. To conclude, reutilization of acidogenic off-gas by diversion to methanogenic phase is a promising strategy for enhancing overall energy recovery during two-phase AD of food waste. However, improvement of the short-lived acidogenic H2 production and H2/CO2 ratio needs further investigation.
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Lameen, Tariq M. H. "Development of a photovoltaic reverse osmosis demineralization fogging for improved gas turbine generation output". Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2756.
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Thesis (Master of Engineering in Electrical Engineering)--Cape Peninsula University of Technology, 2018.Gas turbines have achieved widespread popularity in industrial fields. This is due to the high power, reliability, high efficiency, and its use of cheap gas as fuel. However, a major draw-back of gas turbines is due to the strong function of ambient air temperature with its output power. With every degree rise in temperature, the power output drops between 0.54 and 0.9 percent. This loss in power poses a significant problem for utilities, power suppliers, and co-generations, especially during the hot seasons when electric power demand and ambient temperatures are high. One way to overcome this drop in output power is to cool the inlet air temperature. There are many different commercially available means to provide turbine inlet cooling. This disserta-tion reviews the various technologies of inlet air cooling with a comprehensive overview of the state-of-the-art of inlet fogging systems. In this technique, water vapour is being used for the cooling purposes. Therefore, the water quality requirements have been considered in this thesis. The fog water is generally demin-eralized through a process of Reverse Osmosis (RO). The drawback of fogging is that it re-quires large amounts of demineralized water. The challenge confronting operators using the fogging system in remote locations is the water scarcity or poor water quality availability. However, in isolated hot areas with high levels of radiation making use of solar PV energy to supply inlet cooling system power requirements is a sustainable approach. The proposed work herein is on the development of a photovoltaic (PV) application for driv-ing the fogging system. The design considered for improved generation of Acaica power plant in Cape Town, South Africa. In addition, this work intends to provide technical infor-mation and requirements of the fogging system design to achieve additional power output gains for the selected power plant.
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Codeceira, Neto Alcides. "Assessment of novel power generation systems for the biomass industry". Thesis, Cranfield University, 1999. http://hdl.handle.net/1826/3448.
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The objective of this programme of research is to produce a method for
assessing and optimising the performance of advanced gas turbine power
plants for electricity generation within the Brazilian electric sector. With the
privatisation of the Brazilian electric sector, interest has been given to the
thermal plants and studies have been carried out along with the use of other
alternative fuels rather than fossil fuels.
Biomass is a fuel of increasing interest for power generation systems
since it is clean and renewable. Essentially all biomass power plants in the
Brazilian market today operate on a steam Rankine cycle, which has a poor
efficiency. The Brazilian electricity market has paid attention on Biomass
integrated gasification gas turbine (BIG/GT) combined cycle plants where
solid biomass is gasified. A simple chemical model for representing the
gasifier in the power plant is presented and optimisation of the gasification
process has been applied.
The method for assessing the performance of power plants takes into
account not only energy, but it applies the exergy method, which uses the
second law of thermodynamics and works out the destruction of energy inside
plant components and energy losses rejected to atmosphere. A
thermoeconomic model for assessing the power plant has also been
described.
The optimisation of the assessment method of power plants using
exergy and thermoeconomics has been proposed based on genetic
algorithms. This new technique has been fairly successful at solving
optimisation problems and is easy to implement. The decision of applying
genetic algorithms is due to the complexity of the mathematical model applied
in the performance assessment of power plants.
The assessment of combined cycles like gas / steam cycle, gas / air
cycle, gas / steam / freon cycle, gas / air / freon cycle and chemically
recuperated gas turbine have been investigated. The application of the overall
assessment method helps to understand different and very expensive choices
of power plants before making final decisions.
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Adegoke, Adesola Ayodeji. "Utilizing the heat content of gas-to-liquids by-product streams for commercial power generation". Texas A&M University, 2006. http://hdl.handle.net/1969.1/4217.
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The Gas-to-liquids (GTL) processes produce a large fraction of by-products whose
disposal or handling ordinarily becomes a cost rather than benefit. As an alternative
strategy to market stranded gas reserves, GTL provides middle distillates to an
unsaturated global market and offers opportunities to generate power for commercial
purposes from waste by-product streams, which normally are associated with increased
expenses incurred from additional handling cost.
The key concept investigated in this work is the possibility of integrating the GTL
process with power generation using conventional waste by-product steam streams.
Simulation of the integrated process was conducted with the aim of identifying the
critical operating conditions for successful integration of the GTL and power generation
processes.
About 500 MW of electric power can be generated from 70% of the exit steam
streams, with around 20 to 25% steam plant thermal efficiency. A detailed economic
analysis on the LNG, stand-alone GTL, and Integrated GTL Power-Generation plants
indicates that the integrated system is more profitable than the other options considered.
Justifying the technology and economics involved in the use of the by-product
streams to generate power could increase the net revenue and overall profitability of GTL projects. This technology may be transferable to GTL projects in the world, wherever a
market for generated power exists.
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Srikanth, D. "Novel perovskite type oxides as catalysts for generation of synthesis gas with variable H2 to CO ratio". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2017. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4521.
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Nastev, Miroslav. "Modeling landfill gas generation and migration in sanitary landfills and geological formations". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/NQ39379.pdf.
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Gomes, Eli Eber Batista. "Operational Optimisation of Gas Turbines Distributed Generation Systems in Competitive Electricity Market". Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/3246.
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The development of power generation technologies and the deregulation of the
power market has led to an increasing interest in distributed power generation, mainly
the simultaneous exploitation of electricity and heat from the same energy source,
known as combined heat and power (CHP) systems.
As a consequence of the high competitiveness of power markets and increasing
environmental concerns, distributed power generators have to make reasonable choices
at multiple levels of complexity. A key issue to successfully approaching these
problems is the development of decision making support tools that rely on service life
prediction, intelligent economic dispatch optimisation techniques and condition
monitoring.
This research introduces the concept and development of a decision making
support tool for a mini-pool nerve centre based on distributed gas turbine generation
units operating in a competitive market. The nerve centre framework leads naturally to a
multi-criteria optimisation problem which is solved in this research with a hybrid
genetic algorithm adapted priority list and creep life assessment. The proposed hybrid
approach can result in a significant saving to generators as it efficiently optimises mini-
pool profits and service hours between failures in an acceptable computation time and
accurately. Life cycle assessment combined with generation schedule optimisation can
enhance the maintenance strategy activities and the competitiveness of gas turbine
distributed generation plants, particularly for generators trading energy in a highly
competitive market.
Gas turbine combined heat and power distributed generators are unlikely to
succeed in competing individually with centralised generation technologies within the
present market framework, but they can be more competitive in an information
technology based mini-pool. Additionally, results show that the development of a low
carbon emission power industry can result in an outstanding opportunity for combined
heat and power mainly in power markets currently highly dependent on coal and oil
powered stations.
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Takahashi, Toshihiro, Tatsuji Yamada, Naoki Hayakawa i Hitoshi Okubo. "Space charge behavior in SF6 gas and sequential generation of PD pulses". IEEE, 2000. http://hdl.handle.net/2237/6757.
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Zhang, P. "Development of next generation high temperature materials for high performance gas turbine". Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1474017/.
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Thermal barrier coatings (TBCs) are advanced protective coating systems used to protect metallic substrates at high-temperature application. Currently, the state-of-the-art industrial TBC material is 6-8wt% Y2O3 stabilized ZrO2 (6-8YSZ), but it cannot be used over 1200oC for a long time due to sintering behaviour and phase transformation. The purpose of this thesis was to explore new thermal barrier materials that can be used at high temperature for a long time to replace YSZ. Micron lanthanum titanium aluminum oxide (LaTi2Al9O19, LTA) has been proven as a very promising thermal barrier material due to low thermal conductivity, and excellent phase and thermochemical stability. The main drawback of LTA is the low fracture toughness. Therefore, this thesis studied nano-structured LTA, toughened LTA, and ion doped LTA synthesized by sol- gel method, and LTA and toughened LTA coatings on steel substrate prepared by air plasma spray (APS). The experimental results indicate that compared to micron LTA, the nano-structured LTA had higher coefficients of thermal expansion (CTEs) and comparable thermochemical stability. LTA toughened by 10vol% tetragonal zirconia (LTA-4YSZ) was synthesized by a hybrid sol-gel method. The ceramic composite LTA- 4YSZ had lower thermal conductivity of approximately 1.054 W/(m·K) at room temperature, stable CTEs, better sintering resistance, and mechanical properties. Single phase ion doped LTA by gadolinium was obtained with a Gd3+ content of less than 10mol%, La0.9Gd0.1Ti2Al9O19 (L9G1) had higher CTEs around 11.7×10-6 oC-1 at 950oC, lower thermal conductivity circa. 1.404 W/(m·K) at room temperature, and better sintering resistance than LTA. The APS produced LTA-4YSZ coatings were prepared with optimized granulated powders, which were typical APS coatings with five types of defects: cracks, gaps, cavities, voids, and interspace.
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Danandeh, Anna. "Achieving Reliable Generation \& Delivery of Energy Through Robust Optimization". Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5673.
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In this dissertation, we elaborate on the inherent risks and uncertainties in power systems and associated industries, and develop practical solution methods to eliminate their adverse effects.
our research agenda consists of practice-driven problems in different stages of power generation as follows. (1) Affordable fuel procurement through developing a comprehensive fuel supply chain design and operations planning system for electricity generation companies, (2) reliable electricity generation through incorporating dynamic asset rating concept in the unit commitment problem, and (3) efficient demand management through proposing a job scheduling model for effective local generation consumption.
Since reliability cannot be compromised in energy sector, robust optimization has been adopted as a powerful method to model multiple sources of uncertainty, and to protect the performance of the systems against worst situations. Exact and heuristic methods are then developed and customized to solve these computationally challenging problems. In particular, inspired by the challenges in solving two-stage robust optimization problems, we developed a multi-scenario cutting plane generation algorithm, that considers all the realizations of the uncertainty set at once, and thus, alleviates the computational challenge.
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Retter, Mark Joseph. "PHOTODISSOCIATIVE GENERATION OF A POPULATION INVERSION FOR THE THALLIUM-MERCURY EXCIMER SYSTEM (LASERS, EXCIMERS)". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275407.
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Onabanjo, Tosin. "Techno-economic and environmental assessment of gas turbines utilizing biofuels". Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9280.
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The continued global reliance on fossil fuels with impact on resource depletion, human health, atmospheric pollution and environmental degradation has necessitated a global drive to integrate renewable fuels such as biodiesels. Biodiesels are described as “fuels composed of fatty acid methyl or ethyl esters and obtained from vegetable oils or animal fats”. Their use in energy generation could diversify the world’s energy mix, reduce fossil fuel dependence, reduce emissions and energy cost to bring about other economic benefits, especially for developing economies and rural communities with lack of adequate access to modern energy. A techno-economic and environmental life cycle assessment is however required to ensure that these fuels are fit for use in engines and meet any regulatory standard and sustainability criteria. This thesis has evaluated the use of Jatropha- and microalgae-biodiesel for power generation in two industrial gas turbines with open and combined cycle configuration. This was achieved using a techno-economic and environmental life cycle impact assessment framework. Comparative fuel assessments have been carried out between biodiesels and fossil fuels. Furthermore, the concept of microbial fuel degradation was examined in gas turbines. The thesis have identified Jatropha biodiesel as a worthwhile substitute for conventional diesel fuel, because it has close performance and emission characteristics to conventional diesel fuel with added advantage of being renewable. The consequent displacement of conventional diesel fuel with Jatropha biodiesel has significant environmental benefits. For economic viability and sustainability of gas turbine operated power plants, energy producers require a minimum monetary amount to recover the added cost of operating 100% Jatropha biodiesel. Other integration mechanisms are also available for utilizing the fuel in engines without compromising on plant’s economic performance. In worst case scenarios, where there are no government incentives, local conditions such as high life cycle cost of electricity, open opportunities for distributed and independent power generation from renewable fuels like Jatropha-biodiesel. Furthermore, this thesis has identified salient energy conversion processes that occur in gas turbine fuels, especially with biodiesels and developed a bio-mathematical model, Bio-fAEG to simulate these processes in gas turbines. This platform is a first step in quantifiable assessment and could enable a better understanding of microbial initiated processes.
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Atkinson, Sandra Jane. "Generation and structural characterisation of transient gaseous species". Thesis, University of Canterbury. Chemistry, 2015. http://hdl.handle.net/10092/10495.
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Gas electron diffraction (GED) is a technique that has been developed to study the molecular structure of species in the gas phase. This thesis focuses on the reconstruction of the Canterbury GED apparatus (moved from Edinburgh, UK) and the requirements for modifying the apparatus to incorporate a mass spectrometer (MS) so diffraction and MS data can be obtained within a single experiment.
The combined GED-MS system has been identified in previous work in the Masters group as a necessary development for studying the structure of short-lived species generated in situ. This is particularly true for the study of ketene, which as shown in this thesis, can be generated from several precursors as part of a multiple product pyrolysis system. While GED data for ketene generated from acetic anhydride has been refined, the species formed from the pyrolysis of Meldrum’s acid were determined to be too difficult to deconvolute without additional experimental data from MS. A computational study of possible ketene derivatives that could be studied with a GED-MS apparatus is also presented.
Lastly, this thesis details a structural study of the gas-phase structures of tris(chloromethyl)amine and a family of substituted disilane systems which have been determined in the gas phase for the first time. A comprehensive GED, Raman spectroscopy and ab initio study have been undertaken for tris(chloromethyl)amine [N(CH2Cl)3] which is shown to have a different structure in the solid and gas phase. Further work in the form of a molecular dynamics investigation has been identified as necessary to describe the low amplitude motion of one of the CH2Cl groups in the gas phase to allow for the GED refinement to be completed. The work on the substituted disilane systems X3SiSiXMe2 (X = F, Cl, Br, I) and X3SiSiMe3 (X = H, F, Cl, Br) demonstrates the effect of increased halogen substitution on the electronic effects of the disilanes, and the effect that the methyl groups have as larger halogens increase the steric bulk of the system.
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Allison, Isaiah. "Techno-economic evaluation of associated gas usage for gas turbine power generation in the presence of degradation & resource decline". Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9233.
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This research examined the technical and economic feasibility of harnessing flare gas emissions from oil fields. The outcome would provide the basis for a substantial re-utilization of this waste energy due to the current practice of flaring and use it alternatively as energy for powering oil fields, rural electrification and desalination. Nigeria is used as a case study. Burning fossil fuels have grave environmental impact, amidst increasing global concerns over harmful emissions. This research addresses resource decline and suggests divestment as a partial cure. The gas turbine is subject to degradation of its components as it is used. Though several methods of assessing gas turbine degradation have been developed with varying degrees of success, no one method has addressed issues pertaining to associated gas and its effects on degradation with divestment. Simulation of two single shaft, heavy duty industrial gas turbines; and three aero-derivative industrial gas turbines of the heavy medium and light capacity ranges were carried out for varying operating conditions, to ascertain the effects of degradation when run on associated gas. Thereafter, optimizations for the best power plant engine mix and the least cost of electricity were carried out. Genetic algorithm was used to assess a population of 10,000 individuals over 500 generations; convergence was achieved for different configurations of the five study engines at discount rates of 5% and 10%, over three power ranges. The divestment pattern starts with the lightest aero-derivative industrial gas turbine; the best power plant selection was limited to the two lightest aero-derivatives in the fleet, completely ignoring the heavy engines. A techno-economic, environmental and risk assessment model comprising performance, emission, economics and risk modules was successfully developed to assess gas turbine degradation with divestment. Using this tool, it was confirmed that associated gas usage resulted in degradation of gas turbine performance, an increase in gas collection as well as operation and maintenance costs. Also there was increasingly higher creep life consumption during slow, medium and fast degradation scenarios for both engine sets. The novel technical contribution of the research work therefore is the influence of degradation on the economic use of associated gas as fuel in gas turbine power generation; and the implementation of divestment in the face of fuel decline.
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Ren, Xiaoming. "Laser-driven rotational dynamics of gas-phase molecules: control and applications". Diss., Kansas State University, 2013. http://hdl.handle.net/2097/15954.
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Doctor of PhilosophyDepartment of Physics
Vinod Kumarappan
In this thesis, our work on developing new techniques to measure and enhance field-free molecular alignment and orientation is described. Non-resonant femtosecond laser pulses are used to align and orient rotationally-cold gas-phase molecules. The time-dependent Schrodinger equation is solved to simulate the experimental results. A single-shot kHz velocity map imaging (VMI) spectrometer is developed for characterizing 1D and 3D alignment. Stimulated by a novel metric for 3D alignment proposed by Makhija et al. [Phys. Rev. A 85,033425 (2012)], a multi-pulse scheme to improve 3D alignment is demonstrated experimentally on difluoro-iodobenzene molecules and the best field-free 3D alignment is achieved. A degenerate four wave mixing probe is developed to overcome limitations in VMI measurement; experiments on different types of molecules show good agreement with computational results. Highly aligned linear molecules are used for high harmonic generation experiments. Due to the high degree of alignment, fractional revivals, variation of revival structure with harmonic order and the shape resonance and Cooper minimum in the photoionization cross section of molecular nitrogen are all observed directly in experiment for the first time. Enhanced orientation from rotationally cold heteronuclear molecules is also demonstrated. We follow the theory developed by Zhang et al. [Phys. Rev. A 83, 043410 (2011)] and demonstrate experimentally for the first time that for rotationally cold carbon monoxide an aligning laser pulse followed by a two-color laser pulse can increase field-free orientation level by almost a factor of three compared to using just the two-color pulse.
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Giffin, Amanda. "Investigation of Operating Parameters Influencing Electrostatic Charge Generation in Gas-Solid Fluidized Beds". Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19728.
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Electrostatic charge generation in gas-solid fluidized beds is a significant industrial problem. Associated problems include particle agglomeration and particle wall fouling. In the polymerization industry this may result in "sheets" of fused polymer, due to exothermic reaction causing the melting of the polymer, which can fall off and block the distributor plate disrupting fluidizing gas flow. Additionally, blockage of the catalyst feed or the polymer removal system can take place or the product can become non-uniform. All of these problems require shut-down of the reactor which results in lost production time. While this phenomena has been identified for many years, the mechanisms involved are not well understood, especially wall fouling and the distribution of charge within the bed. Isolation of individual parameters such as hydrodynamics, operating conditions, and material involved is necessary to evaluate how each parameter impacts charge generation during fluidization.
In this thesis, the fluidization system consisted of a stainless steel column, two online Faraday cups, and a retractable distributor plate. This system allowed for the simultaneous measurement of charge within different regions of the bed: the entrained fine particles, the particles adhered to the column wall, and the bulk of the bed. Additionally, mass and particle size distributions were measured and images of the layer of particles adhered to the column wall were taken for comparison. This allowed for a charge distribution comparison and evaluation of wall fouling.
Three different parameters were investigated: duration of fluidization, column wall material, and relative humidity of fluidizing gas. Fluidization time was studied for 15, 30, 60, 120, 180, and 360 min; relative humidity was investigated for 0%, 20%, 40%, 60%, and 80% relative humidity. Both fluidization time and relative humidity were evaluated at four different fluidization gas velocities, two each in the bubbling and slugging flow regimes. Column wall material was evaluated for a stainless steel and carbon steel column at two gas velocities, one each in the bubbling and slugging flow regimes.
Fluidization time was found to influence wall fouling in the bubbling flow regime as the particle layer continued to build as fluidization progressed. In the slugging flow regime, the particle layer developed within 15 minutes of the onset of fluidization. The bubbling flow regime was shown to have a greater capacity for charge generation than the slugging flow regime. This was due to the vigorous mixing in the bubbling flow regime resulting in more particle-particle interactions.
Column wall material was shown to influence wall fouling in the slugging flow regime due to the differences in surface roughness of the columns. This was due to the particle-wall contacts resulting in frictional charging which is the predominant charging mechanism in this flow regime. Charge was also impacted in the bubbling flow regime in those particles that were adhered to the column wall.
Relative humidity was found to influence wall fouling at the lowest gas velocity tested. However, variations in generation of charge occurred at all fluidization gas velocities tested; the charge-to-mass ratios for the particles adhered to the column wall in the slugging flow regime decreased with high relative humidities. This was due to either the formation of a water film layer on the column wall or instantaneous surface water films on the particles throughout fluidization.
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Latcham, Jacob G. (Jacob Greco). "Heat exchanger design for thermoelectric electricity generation from low temperature flue gas streams". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54513.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 33).
An air-to-oil heat exchanger was modeled and optimized for use in a system utilizing a thermoelectric generator to convert low grade waste heat in flue gas streams to electricity. The NTU-effectiveness method, exergy, and thermoelectric relations were used to guide the modeling process. The complete system design was optimized for cost using the net present value method. A number of finned-tube compact heat exchanger designs were evaluated for high heat transfer and low pressure loss. Heat exchanger designs were found to favor either power density or exergy effectiveness to achieve optimal net present value under different conditions. The model proved capable of generating complete thermoelectric flue gas systems with positive net present values using thermoelectric material with a ZT value of 0.8 and second law efficiency of 13%. Complete systems were generated for a number of economic conditions. The best complete system achieved a first law efficiency of 1.62% from a 1500 C flue gas stream at an installed cost of $0.79 per watt.
by Jacob G. Latcham.
S.B.
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Nava, Matthew Jordan. "Generation and observation of reactive intermediates in the gas phase and condensed media". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112360.
Pełny tekst źródłaStreszczenie:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
A molecular beam mass spectrometer (MBMS) has been constructed and upgraded with a laser desorption system. MBMS has allowed for the detection of reactive small molecules including but not limited to P₂ from P₂A₂ (where A = anthracene, C₁₄H₁₀), HCP from PPh₃(HCP)A and various dialkylamino phosphinidenes from their corresponding dibenzo-7-phosphanorbornadiene precursors by mass spectrometry. In cases where the desired reactive small molecule was not detected, MBMS has provided valuable information as to the degradation processes which may be occurring and has guided molecular precursor development. Through the use of highly sensitive microwave spectroscopic techniques, it was found that H₂S and N₂O₃ react to form the elusive molecule HSNO in the gas phase. HSNO is believed to be a crucial intermediate in biological signaling. Through isotopic labeling studies, an accurate structure of HSNO could be derived and subsequent degradation of the molecule was explored. The hexacarboxamide cryptand mBDCA-5t-H₆ was used as a ligand to prepare mono- and bimetallic iron complexes of the formula [Fe₂(mBDCA-5t)]²- and [Fe(mBDCA-5t-H³)]-. Both complexes were observed to react reversibly or irreversibly with CO or NO respectively to afford [(FeEO)-Fe(mBDCA-5t)]²- or [FeEO(mBDCA-5t-H₃)]- where E = C or N. Treatment of [(FeNO)·Fe(mBDCA-5t)]2- with excess NO resulted in the formation of [Fe₂O(mBDCA-5t)]²-, which could be independently prepared by treatment of [Fe₂(mBDCA-5t)]²- with the O-atom transfer reagent N-methylmorpholine N-oxide. The chemistry of peroxide dianion, in the form of the encapsulated complex [O₂[subset]mBDCA- 5t-H₆]²-, has been explored in nonaqueous media. In particular, [O₂[subset]mBDCA-5t-H₆]²- was demonstrated to react with CO gas at 40 °C over the course of several hours to furnish the encapsulated carbonate cryptate, [CO₃[subset]mBDCA-5t-H₆]²-. Through labeling studies, it was confirmed that the carbon of the carbonate was derived from CO. Treatment of [O₂[subset]mBDCA-5t-H₆]²- with CO₂ also affords [CO₃[subset]mBDCA-5t-H₆]²-, but with concomitant oxidation of the solvent. The oxidation of the solvent was found to proceed through the reactive oxidants -O₂COOCO²- and HOOCO₂- and sheds light on oxidative processes which may be occurring in lithium-air cells. Exposure of solid Li₂O₂ to gaseous p-benzoquinone results in the formation of a blue coating on Li₂O₂. This coating was identified as the quinone radical anion Li[p-C₆H₄O₂], which forms via lithium and electron transfer from Li₂O₂. This charge and ion transfer process results in the conversion of Li₂O₂ to LiO₂, a long-sought intermediate in the lithium-air community.
by Matthew Jordan Nava.
Ph. D.
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Myo, Min Win. "Thermochemical conversion characteristics of gas and tar generation from waste biomass and plastics". Kyoto University, 2020. http://hdl.handle.net/2433/253264.
Pełny tekst źródła
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Longe, Timothy A. "Colloidal gas aphrons: generation, flow characterization and application in soil and groundwater decontamination". Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/81014.
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This study examines the fundamental properties of Colloidal Gas Aphrons, CGA, relevant to its application in soil and groundwater decontamination. It also presents the results of laboratory experiments on the applicability of CGA in treating soils contaminated with organic chemicals.
CGA is a collection of spherical, 10 to 100 micron-sized gas bubbles dispersed in an aqueous surfactant solution with a volumetric gas fraction (quality) of at most 0.74. It is characterized by its quality, bubble size, stability and apparent viscosity. The stability can be described by the half life, the time needed for 50% of its liquid phase to separate by gravitational drainage.
CGA is a non-Newtonian fluid. The apparent viscosity is higher than that of its liquid or gas phase and increases with increase in quality. At quality above 0.6, CGA is a pseudoplastic fluid and can be modelled by the power law. In this quality range, apparent viscosity decreases with increase in shear rate. Measured apparent viscosity can be as high as 25 centipoise at low shear rates for a CGA quality of 0.72. But at low quality, CGA is best described by the Bingham fluid model.
CGA flow through porous media follows the discontinuous fluid flow model with the liquid phase advancing faster than the gas phase. The presence of CGA bubbles causes considerable reduction of effective mobility compared to water flow. The bubbles act to reduce the effective flow area by first blocking the wider pores and re-directing flow to narrower pores. The tenacity of the bubbles in the presence of adequate surfactant molecules account for its flow characteristics in porous media.
CGA is more effective in flushing hydrophobic organics from saturated sand-packed columns compared with surfactant flushing. CGA provides the surface active agent needed to lower the interfacial tension of the non-wetting phase and at the same time creates enough viscous force to mobilize any trapped fluid. Its ability to preferentially block large pores in a heterogeneous media and direct fluid flow to smaller pores also contributes to the demonstrated effectiveness as a soil flushing agent.Ph. D.
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de, Vries Jaap. "AN INVESTIGATION OF THE AUTOIGNITION OF POWER GENERATION GAS TURBINE FUEL BLENDS USING A DESIGN OF EXPERIMENTS APPROACH". Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2560.
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Natural gas has grown in popularity as a fuel for power generation gas turbines. However, changes in fuel composition are a topic of concern since fuel variability can have a great impact on the reliability and performance of the burner design. In particular, autoignition of the premixed fuel and air prior to entering the main burner is a potential concern when using exotic fuel blends. To obtain much-needed data in this area, autoignition experiments for a wide range of likely fuel blends containing CH4 mixed with combinations of C2H6, C3H8, C4H10, C5H12, and H2 were performed in a high-pressure shock tube. However, testing every possible fuel blend combination and interaction was not feasible within a reasonable time and cost. Therefore, to predict the surface response over the complete mixture domain, a special experimental design was developed to significantly reduce the amount of 'trials' needed from 243 to only 41 using the Box-Behnkin factorial design methodology. Kinetics modeling was used to obtain numerical results for this matrix of fuel blends, setting the conditions at a temperature of 800 K and pressure of 17 atm. A further and successful attempt was made to reduce the 41-test matrix to a 21-test matrix. This was done using special mixture experimental techniques. The kinetics model was used to compare the smaller matrix to the expected results of the larger one. The new 21-test matrix produced a numerical correlation that agreed well with the results from the 41-test matrix, indicating that the smaller matrix would provide the same statistical information as the larger one with acceptable precision. iii After the experimental matrix was developed using the design of experiments approach, the physical experiments were performed in the shock tube. Long test times were created by "tailoring" the shock tube using a novel driver gas mixture, obtaining test times of 10 millisecond or more, which made experiments at low temperatures possible. Large discrepancies were found between the predicted results by numerical models and the actual experimental results. The main conclusion from the experiments is that the methane-based mixtures in this study enter a regime with a negative temperature coefficient when plotted in Arhennius form. This means that these mixtures are far more likely to ignite under conditions frequently encountered in a premixer, potentially creating hazardous situations. The experimental results were correlated as a function of the different species. It was found that the effect of higher-order hydrocarbon addition to methane is not as profound as seen at higher temperatures (>1100 K). However, the ignition delay time could still be reduced by a factor two or more. It is therefore evident that potential autoignition could occur within the premixer, given the conditions as stated in this study.M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Aerospace Engineering
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LECUNA, TOVAR MARICARMEN LEANDRA. "Scale down of a dynamic generator of VOC reference gas mixtures". Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2676926.
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A system for the dynamic preparation of reference gas mixtures based on the diffusion technique has been developed by the National Metrology Institute of Italy i.e. the Istituto Nazionale di Ricerca Metrologica (INRIM). The gravimetric method used for the estimation of the diffusion rate and consequent concentration, gives the system the property to be a primary standard. The system can generate mixtures with low uncertainty and high stability in the 20 nmol.mol-1 - 2.5 µmol.mol-1 concentration range with a 5% (k = 2) expanded uncertainty for mixtures of acetone in air. Based on this system, a transportable device for the generation of VOC reference gas mixtures to be used as calibration standard was designed and developed. The methodology used for the scale down included several steps. An initial characterization and modelling of the primary device was done using computational tools. Based on the response of the computational model to the different physical quantities, a set of design parameters was identified. The thresholds for this set of parameters were established and translated into a set of design criteria to consider in order to keep the metrological performance target. After the design and development of the transportable device, a metrological characterization was carried out, to verify its capabilities. The metrological characterization of the generator was done in the Dutch National Metrology Institute i.e. the Van Swinden Laboratory (VSL) trough Cavity Ring Down Spectroscopy (CRDS) analyses to evaluate the linearity, the reproducibility and the short term stability. The results for the generation of methanol mixtures with molar fractions in the 80-150 nmol.mol-1 range, were 99.6% linear, with a reproducibility after 3 days within 2,9% and a short term stability better than 1% per hour. Repeatable measurements of the generated concentration were obtained for three different molar fractions, with the use of both CRDS (VSL) and the GC/FID (INRIM). A flow of the desired dry pure carrier gas can be connected to the device. The presence of water in the system has not been taken into account and further analyses should be done before introducing it to the system. Water presence might affect the adsorption rate, and consequently the flushing time before normal operation. This transportable device is able to perform in-situ calibration of instruments and has been designed to generate gas mixtures of up to four species at a time.
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Thomson, Rachel Camilla. "Carbon and energy payback of variable renewable generation". Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/8875.
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The continued drive to reduce Greenhouse Gas (GHG) emissions in order to mitigate climate change has led to an increase in demand for low-carbon energy sources, and the development of new technologies to harness the available energy in the wind, waves and tides. Many controversies surround these technologies, however, particularly with regards to their economic cost, environmental impacts and the implications of the variability of their output for security of the electricity supply. In order to make informed policy decisions on future developments of the electricity system, it is necessary to address these controversies and confirm the environmental, economic and social sustainability of these new renewable generators. This thesis specifically examines two key issues: whether new variable-output renewable energy generators actually deliver a net reduction in greenhouse gas emissions over their lifetimes, and whether they produce a viable energy return on energy investment. Although renewable energy sources are themselves ‘carbon free’, GHG emissions (and energy consumption) occur during the construction, maintenance and decommissioning of the generator infrastructure required to convert this energy into electricity. Furthermore, the variability of the output power from such generators has implications for the operation of the grid - there may be a requirement for additional reserve capacity and the increased part-loading of conventional plant is likely to reduce its operating efficiency. Carbon and energy paybacks are measures of the time required for a new renewable installation to offset these life cycle impacts. The work presented in this thesis examines both the life cycle impacts and the GHG emissions displacement of variable renewable generation, using Great Britain as a case study, in order to provide a basis for significantly more robust and reliable estimates of carbon and energy paybacks. The extensive literature survey concentrates on two key areas: current calculation methodologies and estimates for life cycle carbon and energy consumption of power generators; and the marginal emissions displacement of variable renewable generation. A detailed life cycle assessment of the Pelamis wave energy converter is presented, which sets the embodied carbon and energy in the context of the wider environmental impacts and includes an examination of the effect of different assumptions on the analysis results. In order to investigate the true emissions displacement of renewable generation, a historical analysis of real data from the National Grid was carried out, identifying the marginal displacement factor of wind power and taking into account the effect of the efficiency penalties of conventional plant. The findings of the analyses presented in this thesis are combined with information from the literature to examine the actual carbon and energy payback of existing renewable generation infrastructure on the British grid, and to provide detailed recommendations for future carbon and energy payback calculations.
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Kysel, Stanislav. "Energetický paroplynový zdroj na bázi spalování hutnických plynů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229801.
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The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.
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Kysel, Stanislav. "Energetický paroplynový zdroj na bázi spalování hutnických plynů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230245.
Pełny tekst źródłaStreszczenie:
The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.