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1
Klíma, Petr. "Parní turbina rychloběžná kondenzační." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231803.
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ith one controlled extraction and one uncontrolled extraction, calculation of the flow channel at all stage, design and calculation of the regulation valve and create connection diagram of steam turbine and air cooled condenser. At the beginning of this work is an overview of manufacturers of steam turbines and their unified products. Master thesis was developer with G-Team, a.s. as using calculations and the instructions given in the recommended literature with supporting CFD simulations to determine the loss coefficients and FEA simulations to determine the eigenfrequencies blades.
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Jahn, Ingo H. J. "Leaf seals for gas and steam turbines." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670066.
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Chaluvadi, Venkata Siva Prasad. "Blade-vortex interactions in high pressure steam turbines." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621152.
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Aubry, James R. "Non-contacting shaft seals for gas and steam turbines." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:84b3dd8d-24e6-459a-8144-8dca191cef4b.
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Improvements upon current gas turbine sealing technology performance are essential for decreasing specific fuel consumption to meet stringent future efficiency targets. The clearances between rotating and static components of a gas turbine, which need to be sealed, vary over a flight cycle. Hence, a seal which can passively maintain an optimum clearance, whilst preventing contact between itself and the rotor, is extremely desirable. Various configurations of a Rolls Royce (RR) seal concept, the Large Axial Movement Face Seal (LAMFS), use static pressure forces to locate face seals. Prototypes were tested experimentally at the Osney Thermofluids Laboratory, Oxford. Firstly a proof-of concept rig (simulating a 2-D seal cross-section) manufactured by RR was re-commissioned. The simplest configuration using parallel seal faces induced an unstable seal housing behaviour. The author used this result, CFD, and analytical methods to improve the design and provide a self-centring ability. A fully annular test rig of this new seal concept was then manufactured to simulate a 3D engine representative seal. The full annulus eliminated leakage paths unavoidable in the simpler rig. A parametric program of experiments was designed to identify geometries and conditions which favoured best-practice design. The new seal design is in the process of being patented by Rolls Royce. A 'fluidic' seal was also investigated, showing very promising results. A test rig was manufactured so that a row of jets could be directed across a leakage cross-flow. An experimental program identified parameters which could achieve a combined lower leakage mass flow rate compared with the original leakage. Influence of jet spanwise spacing, injection angle, jet to mainstream pressure ratio, mainstream pressure difference and channel height were analysed. It is hoped this thesis can be used as a tool to further improve these seal concepts from the parametric trends which were identified experimentally.
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Zamri, Mohd Y. "An improved treatment of two-dimensional two-phase flows of steam by a Runge-Kutta method." Thesis, University of Birmingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251270.
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Skillings, S. A. "An analysis of the condensation phenomena occurring in wet steam turbines." Thesis, Open University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380667.
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Yau, K. K. "Fog droplet deposition and movement of coarse water in steam turbines." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384521.
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McFarland, Jacob Andrew. "Conceptual Design and Instrumentation Study for a 2-D, Linear, Wet Steam Turbine Cascade Facility." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36165.
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The design of last stage low pressure steam (LP) turbines has become increasingly complicated as turbine manufacturers have pushed for larger and more efficient turbines. The tip sections of these LP turbines encounter condensing wet steam at high velocities resulting in increased losses. These losses are difficult to predict with computational fluid dynamic models. To study these losses and improve the design of LP turbines a study was commissioned to determine the feasibility and cost of a steam cascade facility for measuring low pressure turbine blade tip section aerodynamic and thermodynamic performance.This study focused on two objectives: 1) design a steam production facility capable of simulating actual LP turbine operating conditions, and 2) design an instrumentation system to measure blade performance in wet steam. The steam production facility was designed to allow the test section size to be selected later. A computer code was developed to model the facility cycle and provide equipment requirements. Equipment to meet these requirements, vendors to provide it, and costs were found for a range of test section sizes. A method to control the test section conditions was also developed.
To design the instrumentation system two methods of measuring blade losses through entropy generation were proposed. The first method uses existing total pressure probe techniques. The second method uses advanced particle imaging velocimetry techniques possibly for the first time in wet steam. A new method is then proposed to modify the two techniques to take measurements at non-equilibrium states. Finally accuracy issues are discussed and the challenges associated with achieving periodic flow in this facility are investigated.
Master of Science
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Többen, Dennis [Verfasser]. "Heat Transfer Mechanisms in Steam Turbines During Warm-Keeping Operation / Dennis Többen." München : Verlag Dr. Hut, 2019. http://d-nb.info/1202168604/34.
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Guha, Abhijit. "The fluid mechanics of two-phase vapour-droplet flow with application to steam turbines." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385423.
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Leahy, Mark John. "Detecting seal-to-rotor rubs within steam turbines : the suitability of acoustic emission monitoring." Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539403.
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Topel, Monika. "Steam Turbine Thermal Modeling for Improved Transient Operation." Licentiate thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156196.
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The growing shares of renewable energy sources in the market and solar thermal power applications have set higher requirements on steam turbine operation.These requirements are related to flexibility during transients. A key aspect sought of such flexibility is the capability for fast starts. Due to the varying temperature gradients during start-up, the speed at which the turbine can start is constrained by thermal stresses and differential expansion. These phenomena either consume component lifetime or may result in machine failure if not carefully controlled. In order to accomplish faster starts while ensuring that lifing requirements are preserved, it is important to analyze the thermal behavior of the machine. For this, a transient thermal model was developed with a focus on adaptability to different turbine sizes and geometries. The model allows for simple and fast prediction of thermo-mechanical properties within the turbine metal, more importantly, of the temperature distribution and the associated thermal expansion. The next step of this work was to validate the assumptions and simplifications of the model. This was done through the study and comparison of two turbines against measured operational data from their respective power plants. Furthermore,validation studies also included comparisons concerning the geometric detail level of the model. Overall, comparison results showed a large degree of agreement with respect to the measured data and between the geometric detail levels. The validated model was then implemented in studies related to reducing start-up times and peak differential expansion. For this, the potential effects of turbine temperature maintaining modifications were investigated and quantified.The modifications studied included: increasing gland steam pressure, increasing back pressure and increasing barring speed. Results yielded significant improvements starting from 9.5% in the start-up times and 7% in the differential expansion.QC 20141128
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Liu, Ching-Po. "Developing a procedure to reduce thermal shock influence in a steam turbine due to a cold start /." Online version of thesis, 1988. http://hdl.handle.net/1850/10214.
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Topel, Monika. "Improving Concentrating Solar Power Plant Performance through Steam Turbine Flexibility." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211780.
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The amount of incoming solar energy to earth is greater than any other source. Among existing technologies to harness solar energy there is concentrating solar power (CSP). One advantage of CSP is that is dispatchable, meaning that it can provide power even when the sun is not shining. However, CSP is undergoing challenges which hinder its development such as operating variabilities caused by the fluctuations of the sun or the fact that these systems are not yet cost competitive with respect to other technologies. One way of improving the performance of CSP plants (CSPPs) is by increasing their operational flexibility, specifically their capability for fast starts. In this way it is possible for the CSPP to harness the solar energy as soon as possible, thus producing more energy and increasing its profitability. Over 90% of CSPPs use a steam turbine to generate electricity. Steam turbines are not currently designed with the flexibility required by the CSP application. Steam turbine start-up is limited by thermal stress and differential expansion. If not carefully controlled, these phenomena either consume lifetime or even result in machine failure. The aim of this work was to understand the improvement potential of steam turbine start-up and quantify this in terms of CSPP performance indicators. For this, a thermo-mechanical steam turbine model was developed and validated. The model was then used to analyze potential improvements and thermal constraints to steam turbine start-up operation. Furthermore, a CSP plant techno-economic model was developed including steam turbine details. This modeling approach including two levels of detail allowed for the particularities of the component to be included within the dynamics of the plant and thus be able to connect the perspectives of the equipment manufacturer with those of the plant operator. Reductions of up to 11.4% in the cost of electricity were found in the studies carried out.QC 20170814
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Qur'an, Omar Ali Sammour. "Design criteria and performance of steam turbines in a CPP plant for electrical power generation." Thesis, University of Hertfordshire, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247306.
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Nunes, Bonaventure R. "Numerical Loss Prediction of high Pressure Steam Turbine airfoils." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51742.
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Steam turbines are widely used in various industrial applications, primarily for power extraction. However, deviation for operating design conditions is a frequent occurrence for such machines, and therefore, understanding their performance at off design conditions is critical to ensure that the needs of the power demanding systems are met as well as ensuring safe operation of the steam turbines. In this thesis, the aerodynamic performance of three different turbine airfoil sections ( baseline, mid radius and tip profile) as a function of angle of incidence and exit Mach numbers, is numerically computed at 0.3 axial chords downstream of the trailing edge. It was found that the average loss coefficient was low, owing to the fact that the flow over the airfoils was well behaved. The loss coefficient also showed a slight decrease with exit Mach number for all three profiles. The mid radius and tip profiles showed near identical performance due to similarity in their geometries. It was also found out that the baseline profile showed a trend of substantial increase in losses at positive incidences, due to the development of an adverse pressure zone on the blade suction side surface. The mid radius profile showed high insensitivity to angle of incidence as well as low exit flow angle deviation in comparison to the baseline blade.Master of Science
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Tofoli, Fabio [UNESP]. "Análise do comportamento de grandezas e parâmetros que determinam o dimensionamento de turbomáquinas a vapor." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/99311.
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Este trabalho tem como objetivo a análise da influência de parâmetros adimensionais e grandezas dimensionais no projeto de turbomáquinas operando em diferentes situações de pressão, temperatura e vazão mássica de vapor. O trabalho é divido em duas partes principais, sendo que inicialmente são analisados os parâmetros adimensionais e as grandezas dimensionais que influenciam diretamente o valor do rendimento interno das turbomáquinas térmicas que utilizam o vapor como fluido de trabalho. Na segunda parte do trabalho são abordadas as classes de pressão e rotação específica, e sua influência no comportamento de parâmetros adimensionais. A aplicação dos resultados está diretamente ligada a especificação de turbomáquinas em sistemas de cogeração para aproveitamento de fluxos térmicos provenientes de processos, queima de combustíveis ou gases de escape de uma máquina térmica, para os quais os projetistas necessitam estimar o rendimento de tais componentes por ocasião da análise de viabilidade econômica.
This work has as objective the analysis of the influence of dimensionless parameters and dimensional greatness in the project of turbomachinery operating in different pressure situations, temperature and flow steam. This work is shared in two main parts, which are initially analyzed the dimensionless parameters and the dimensional greatness that directly influence the internal efficiency of the thermal turbomachinery that using steam as the working fluid. In the second part of the work are accosted the classes of pressure and specific rotation, and its influence on the behavior of dimensionless parameters. The application of the results is directly linked to the specification of turbomachinery in cogeneration systems for use of heat flows from processes, burning of fuel or the exhaust gases of a thermal machine, for which the designers needs to estimate the efficiency of such components at analysis of economic feasibility.
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Hartigan, Timothy James. "Effects of notches and fretting on fatigue of steam turbine materials at 524°C." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/16726.
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Blevins, Linda G. "Effects of high levels of steam addition on NOx̳ reduction in laminar opposed flow diffusion flames." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042010-020128/.
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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992.On t.p. "x̳" is subscript. Vita. Abstract. Includes bibliographical references (leaves 92-97). Also available via the Internet.
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Collier, D. A. "A comparative history of the development of the leading stationary steam engine manufacturers of Lancashire, c. 1800-1939." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370407.
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Tofoli, Fabio. "Análise do comportamento de grandezas e parâmetros que determinam o dimensionamento de turbomáquinas a vapor /." Guaratinguetá : [s.n.], 2009. http://hdl.handle.net/11449/99311.
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Resumo: Este trabalho tem como objetivo a análise da influência de parâmetros adimensionais e grandezas dimensionais no projeto de turbomáquinas operando em diferentes situações de pressão, temperatura e vazão mássica de vapor. O trabalho é divido em duas partes principais, sendo que inicialmente são analisados os parâmetros adimensionais e as grandezas dimensionais que influenciam diretamente o valor do rendimento interno das turbomáquinas térmicas que utilizam o vapor como fluido de trabalho. Na segunda parte do trabalho são abordadas as classes de pressão e rotação específica, e sua influência no comportamento de parâmetros adimensionais. A aplicação dos resultados está diretamente ligada a especificação de turbomáquinas em sistemas de cogeração para aproveitamento de fluxos térmicos provenientes de processos, queima de combustíveis ou gases de escape de uma máquina térmica, para os quais os projetistas necessitam estimar o rendimento de tais componentes por ocasião da análise de viabilidade econômica.Abstract: This work has as objective the analysis of the influence of dimensionless parameters and dimensional greatness in the project of turbomachinery operating in different pressure situations, temperature and flow steam. This work is shared in two main parts, which are initially analyzed the dimensionless parameters and the dimensional greatness that directly influence the internal efficiency of the thermal turbomachinery that using steam as the working fluid. In the second part of the work are accosted the classes of pressure and specific rotation, and its influence on the behavior of dimensionless parameters. The application of the results is directly linked to the specification of turbomachinery in cogeneration systems for use of heat flows from processes, burning of fuel or the exhaust gases of a thermal machine, for which the designers needs to estimate the efficiency of such components at analysis of economic feasibility.
Orientador: Paulo Magalhães Filho
Coorientador: José Nédilo Carrinho de Castro
Banca: Carlos Daniel Ebinuma
Banca: José Rui Camargo
Mestre
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Jamaica, Alejandro, Koon Ki Mak, and Yi Zheng. "Benchmarking Small Wind Turbines for the Swedish Market : A case study of Chinese, Mexican and Swedish Manufacturers." Thesis, Linnéuniversitetet, Ekonomihögskolan, ELNU, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-8103.
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This thesis researches for suitable Small Wind Turbines for the Swedish market by studying the Chinese, Mexican and Swedish manufacturers. The purpose of this study is to find the most important factors that influence buyers‟ decision making. Therefore, a benchmarking model is developed based on these factors in order to compare each product‟s performance. The theoretical approaches used as basis for this investigation are: benchmarking, buying behavior and physics theories. Thereafter, the model developed by the authors is used as a main tool to conduct the product‟s performance evaluation, which is based on specific features and parameters. This procedure has been followed in order to answer the main research question: „How can Chinese and Mexican SWT manufacturers meet the demands from Swedish market?‟ The analysis shows that many Chinese and Mexican Small Wind Turbines present a high and acceptable performance for the Swedish market. However, there have been identified some reasons to explain why these manufacturers have not entered the market.
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Blondel, Frédéric. "Couplages instationnaires de la vapeur humide dans les écoulements de turbines à vapeur." Phd thesis, Ecole Centrale de Lyon, 2014. http://tel.archives-ouvertes.fr/tel-00985725.
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Le bon fonctionnement et les performances des turbines à vapeur sont liés à l'état de la vapeur et notamment au taux d'humidité qu'elle contient. EDF souhaite pouvoir maîtriser les phénomènes spécifiques à ces problématiques afin d'améliorer l'utilisation et l'évolution de ses turbines. Le sujet de recherche concerne la modélisation de la formation de l'humidité dans un corps de turbine et l'étude des couplages entre la phase liquide et les instationnarités. Dans ce contexte, la démarche adoptée est la suivante : la présence d'humidité est prise en compte à l'aide d'un modèle homogène, couplé à des modèles de condensation permettant de prendre en compte les phénomènes hors-équilibre thermodynamique : le grossissement et la nucléation des gouttes d'eau dans la vapeur. Pour mener à bien les calculs, des méthodes numériques adaptées aux gaz réels ont été utilisées et testées à l'aide d'un code monodimensionnel avant d'être intégrées dans le code 3D elsA. Deux types de modèles de condensation ont été mis en œuvre, considérant ou non la polydispersion des gouttes dans la vapeur. Les couplages instationnaires entre la condensation et l'écoulement principal ont été étudiés à différents niveaux d'observations (1D, 1D − 3D, 3D). Il a été montré que la méthode des moments apporte une richesse supplémentaire par rapport à un modèle mono-dispersé, et permet de mieux capter les couplages instationnaires entre l'humidité et le champ principal.
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Gomez, Pablos Calvo Raquel. "Sustainability of Polymer Production Technologies." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Polypropylene is the second-most widely demanded commodity plastic. LyondellBasell is leading this market by producing and licensing the technologies to produce it; however, these technologies use a significant amount of energy in the form of electricity and steam.
Market trends, continuous competition and new strict policies drive LyondellBasell to improve and optimize the existing processes as sustainability impact becomes more challenging.
On this project we propose new sustainable configurations, that can be applied in some sections of the actual processes, and that will potentially reduce the CO2 emissions and energy consumptions in a remarkable way. By improving energy efficiency, resources are reduced to a minimum, reaping benefits for the environment.
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Lothon, Alain. "Pyrométrie photothermique impulsionnelle à fibres optiques : application à la mesure de la température des aubages mobiles des turbines à vapeur d'EDF." Châtenay-Malabry, Ecole centrale de Paris, 1993. http://www.theses.fr/1993ECAP0328.
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L'optimisation du fonctionnement à charge partielle des turbines à vapeur a conduit EDF à réaliser une sonde optique capable de mesurer la température des aubages fixes et mobiles situés au niveau du corps basse pression. Pour ce faire, nous mettons en œuvre une méthode pyrométrique récente qui permet d'affranchir totalement la mesure de température de l'influence des flux infrarouges parasites issus du milieu environnant et réfléchis par la surface des aubages. Le principe de cette méthode repose sur l'effet photothermique que l'on obtient, dans notre cas, a l'aide d'un laser impulsionnel. L'étude théorique de la variation de température et du signal photothermique qui en résulte nous permet de déterminer les conditions optimales de mise en œuvre de la méthode. Nous décrivons en détail les différents montages expérimentaux utilisés pour étudier la faisabilité de la méthode dans le cas de notre application. Nous exposons les différentes possibilités de mesure qu'autorise la méthode pyrométrique utilisée et montrons que seule une mesure effectuée dans deux bandes spectrales de détection est compatible avec les conditions expérimentales de notre application. Nous établissons expérimentalement les performances de la pyrométrie photothermique impulsionnelle a fibres optiques. La réalisation de la sonde optique fait l'objet d'une étude détaillée dans laquelle nous explicitons les solutions technologiques retenues. La mise en œuvre in situ de la sonde optique montre que la méthode est utilisable dans le cadre de notre application mais qu'il est impératif de mesurer simultanément, à chaque tir laser, le signal photothermique dans deux bandes spectrales de détection afin de s'affranchir des variations potentielles des paramètres géométriques tels que la distance de visée par exemple.
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Fakhari, Keramat [Verfasser], Reinhard [Gutachter] Mönig, and Horst [Gutachter] Stoff. "Numerical modeling and investigation of unsteady phenomena in condensing flows of industrial steam turbines / Keramat Fakhari ; Gutachter: Reinhard Mönig, Horst Stoff ; Fakultät für Maschinenbau." Bochum : Ruhr-Universität Bochum, 2011. http://d-nb.info/1209358298/34.
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Karlsson, Christer. "On the On-line Tools for Treatment of Deterioration in Industrial Processes." Doctoral thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-905.
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For industrial processes high availability and efficiency are important goals in plant operation. This thesis presents studies and development of tools for on-line treatment of process deterioration and model and sensor errors in order to achieve these goals. Deterioration of measurement devices, process components and process models has caused economical losses, plant failure and human losses. The development of on-line methods to prevent such losses is of special interest and has been conducted at The Department of Energy Technology, Mälardalen University. Important technological obstacles to implementing automatic on-line methods have been identified, such as data selection for adaptation and adaptation of data-driven models to new states. A new method has been developed for decision support by combining artificial intelligence methods and heat and mass balance models, and concepts are proposed for decision support in order to detect developing faults and to conduct appropriate maintenance actions. The methods have been implemented in simulation environment and evaluated on real process data when available. The results can be sumarised as successful development of a decision support method on a steam turbine by combining artificial neural networks and Bayesian networks, and identification of important obstacles for automation of methods for adaptation of heat and mass balance process models and data-driven models when they are subject to deterioration.
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Čípek, Petr. "Parní turbina." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-231039.
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The aim of the thesis is to design a high-speed steam turbine as a small energy source. Steam turbine consists of a high-pressure, a medium-pressure and a low-pressure part with a removable condensing module. High-pressure part is designed to perform a single-stage radial turbine with axial steam outlet. The work also includes the layout of the modules and sections. To design individual parts are used steam table „X-steam“.
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Marques, Frederico Augusto Spolidorio. "Implementação e validação pratica de modelos multidisciolinares abordados em uma central de co-geração de energia eletrica." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259510.
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Orientador: Luiz Carlos Pereira da SilvaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Este projeto busca relacionar diversos aspectos interdisciplinares envolvidos em uma central de co-geração de energia elétrica. Motivado pela crescente inserção de centrais de geração distribuída operando de forma ilhada ou paralela ao sistema, foram desenvolvidos modelos mecânicos (térmicos e dinâmicos) e elétricos buscando representar os diversos equipamentos envolvidos em uma central de geração em um nível industrial. Baseado nesta concepção, optou-se pela geração de energia através de máquinas térmicas (turbinas a vapor) impulsionadas pela energia proveniente da queima de biomassa restante de diferentes processos industriais. Os modelos teóricos aqui representados foram numericamente simulados com parâmetros obtidos em um estudo de caso real. Seus resultados foram então comparados qualitativamente e quantitativamente contra as variáveis reais do processo analisado. Ao consolidar esta ferramenta de estudo, o simulador mostrou-se eficiente no treinamento de operadores de casas de forças, sendo capaz de esclarecer as interferências entre o nível de carga com as demais variáveis envolvidas em seu processo
Abstract: This project intends to gather several interdisciplinary aspects common to a co-generation power plant. Driven by the increasing amount of distributed generation units operating on island or parallel mode with the network, some mechanical (thermo and dynamic) and electrical models were developed in order to represent the equipments usually installed on an industrial size power station. Based on this concept, the more convenient option was to proceed the evaluation through turbo machinery (steam turbine) driven by the energy acquired from the heat power on burning byproducts of industrial processes. The theoretical models were simulated with parameters obtained from a real case study. The results were then finally compared with real process information acquired from field research. In order to consolidate this computational tool, the simulator has shown efficient results on training power station operators on clarifying the impacts of load level on the other relevant variables on their processes
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
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Guarinelo, Júnior Flávio Fernando. "Análise termodinâmica de ciclo combinado operando fora das condições de projeto." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265044.
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Orientador: Jorge Isaías Llagostera BeltránTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: O atendimento da demanda crescente de eletricidade, associado à necessidade do cumprimento de metas de emissões de gases causadores do aquecimento global, será um grande desafio ao setor elétrico nas próximas décadas. A geração de eletricidade ainda necessitará de combustíveis fosseis por muitos anos e a busca por eficiência energética nos processos térmicos que envolvem as usinas termoelétricas será determinante ao cumprimento das metas de emissões. Neste contexto, o ciclo combinado tem sido apresentado como a tecnologia mais eficiente e com o menor impacto ambiental quando se considera o uso de combustíveis fósseis na geração de eletricidade. Possui curtos prazos de instalação e custos relativamente baixos em comparação às outras tecnologias, quer façam uso de fontes renováveis ou não, e tem passado por processos de evolução tecnológica que permitem eficiências de até 62%. Mesmo que apresente características tão favoráveis, o desempenho do ciclo combinado é uma tecnologia sensível quando passa a operar em condições ambiente diferentes daquelas especificadas em projeto. A análise do comportamento do desempenho nestas condições é de extrema importância para fins de avaliação da viabilidade técnica e econômica do ciclo no local a ser instalado e é o tema central deste trabalho. Portanto, a proposta deste trabalho é analisar termodinamicamente a operação do ciclo combinado operando em condições fora-de-projeto (off design) através do desenvolvimento de um sistema de equações não lineares que representam os balanços de massa e energia de cada componente e as relações entre si. O conjunto de equações do modelo analítico é resolvido através de uma ferramenta computacional comercialmente disponível, a qual permite a definição de variáveis independentes e das restrições necessárias a uma solução objetiva. A lógica empregada na solução do conjunto de equações define uma relação direta entre as mesmas através da redução do grau de liberdade de uma determinada variável. A modelagem analítica revelou ser uma ferramenta importante na investigação do comportamento do desempenho do ciclo como um todo e a dependência termodinâmica entre os seus componentes
Abstract: The worldwide growing demand for electricity associated with global warming issues is becoming a great challenge to the electric sector for the next decades. As the power generation still depends on the fossils fuels as main source, the combined cycle is further recognized for its better environmental performance in mitigating air pollution and by reducing the global warming effects. Based on this perspective, the combined cycle has been presented as the most efficient technology, by providing advantages due to its smaller environmental impact when considering the use of fossils fuels in power generation. It is characterized by its low capital cost and short construction lead time in comparison with other technologies, whatever type of renewable fuel is being used or not, it has been experiencing a technological evolution that boost its overall efficiencies to more than 62%. Even though it has been presented with such favorable characteristics, the overall efficiency of the combined cycle is very sensitive to environmental conditions as well as running from the base load. By analyzing all thermodynamic parameters in the combined cycle under off - design conditions it can provide a better understanding in order to develop a technical and economical feasibility and it is the core issue of this work. Therefore, the proposal of this work aims to develop a system of non linear equations that represent the mass and energy balances of all component and the thermodynamic relationships among them. The group of equations of the analytical model is solved through a computational tool, commercially available, which allows the definition of independent variables and all constraint needs to reach a target solution. The logic employed in solving the system of equations defines a direct relationship among each combined cycle's component through the reduction of the degree of freedom of a certain variable. The analytical modeling revealed to be an important tool in the investigation of the combined cycle operation behavior as a whole and the thermodynamic dependence among all components
Doutorado
Termica e Fluidos
Doutor em Engenharia Mecânica
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Fendler, Yoann. "Analyse des phénomènes liés à la présence de la phase liquide dans les turbines à vapeur et élaboration de modèles méridiens pour en prédire les effets." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00818336.
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Lors de sa détente dans une turbine, la vapeur subit une chute d'enthalpie qui entraîne sa condensation spontanée sous forme d'un nuage de gouttelettes submicroniques. Ces gouttes vont se déposer sur les aubes aval et y former un film d'eau. Ce dernier est arraché sous l'effet de l'écoulement de vapeur environnant ce qui crée des gouttes de quelques dizaines de microns qui peuvent se redéposer sur les aubes aval. Ces phénomènes sont à l'origine de pertes, généralement regroupées sous le terme générique de "pertes par humidité", estimées grâce à la loi de Baumann. Le but de cette thèse est de mettre en place dans un code méridien des modèles permettant la prise en compte des phénomènes de condensation, de déposition et d'écoulement des films liquides afin de pouvoir estimer les pertes liées à chacun d'entre eux. Dans cette optique un modèle diphasique homogène permettant d'avoir accès à la fraction massique de liquide et au nombre de gouttes est implanté dans le code méridien. Ce modèle est validé sur un cas test expérimental de détente en tuyère et alimente le modèle de déposition. Les contributions de la diffusion, de la turbophorèse, de la thermophorèse, de la gravité et de l'inertie des gouttes à la déposition sont étudiées. Il apparaît nécessaire de prendre en compte la diffusion, la turbophorèse et la déposition inertielle sur les bords d'attaque des aubes. Un modèle permettant d'avoir accès à l'épaisseur et à la vitesse d'un film liquide soumis au cisaillement d'un écoulement environnant, à la force de frottement sur la paroi et aux effets de la rotation est mis en place. Ce modèle est validé par rapport à des résultats expérimentaux d'écoulement de film liquide sur une plaque plane dans des conditions proches de celles rencontrées en turbine à vapeur basse pression. Finalement, un calcul réalisé sur une géométrie réelle de turbine basse pression de 8 étages permet de démontrer l'applicabilité de la méthodologie mise en place sur un cas industriel. Les contributions des phénomènes étudiés aux pertes par humidité sont explicitées.
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Al-Anfaji, Ahmed Suaal Bashar. "The optimization of combined power-power generation cycles." Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/15485.
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An investigation into the performance of several combined gas-steam power generating plants’ cycles was undertaken at the School of Engineering and Technology at the University of Hertfordshire and it is predominantly analytical in nature. The investigation covered in principle the aspect of the fundamentals and the performance parameters of the following cycles: gas turbine, steam turbine, ammonia-water, partial oxidation and the absorption chiller. Complete thermal analysis of the individual cycles was undertaken initially. Subsequently, these were linked to generate a comprehensive computer model which was employed to predict the performance and characteristics of the optimized combination. The developed model was run using various input parameters to test the performance of the cycle’s combination with respect to the combined cycle’s efficiency, power output, specific fuel consumption and the temperature of the stack gases. In addition, the impact of the optimized cycles on the generation of CO2 and NOX was also investigated. This research goes over the thermal power stations of which most of the world electrical energy is currently generated by. Through which, to meet the increase in the electricity consumption and the environmental pollution associated with its production as well as the limitation of the natural hydrocarbon resources necessitated. By making use of the progressive increase of high temperature gases in recent decades, the advent of high temperature material and the use of large compression ratios and generating electricity from high temperature of gas turbine discharge, which is otherwise lost to the environment, a better electrical power is generated by such plant, which depends on a variety of influencing factors. This thesis deals with an investigation undertaken to optimize the performance of the combined Brayton-Rankine power cycles' performance. This work includes a comprehensive review of the previous work reported in the literature on the combined cycles is presented. An evaluation of the performance of combined cycle power plant and its enhancements is detailed to provide: A full understanding of the operational behaviour of the combined power plants, and demonstration of the relevance between power generations and environmental impact. A basic analytical model was constructed for the combined gas (Brayton) and the steam (Rankine) and used in a parametric study to reveal the optimization parameters, and its results were discussed. The role of the parameters of each cycle on the overall performance of the combined power cycle is revealed by assessing the effect of the operating parameters in each individual cycle on the performance of the CCPP. P impacts on the environment were assessed through changes in the fuel consumption and the temperature of stack gases. A comprehensive and detailed analytical model was created for the operation of hypothetical combined cycle power and power plant. Details of the operation of each component in the cycle was modelled and integrated in the overall all combined cycle/plant operation. The cycle/plant simulation and matching as well as the modelling results and their analysis were presented. Two advanced configurations of gas turbine cycle for the combined cycle power plants are selected, investigated, modelled and optimized as a part of combined cycle power plant. Both configurations work on fuel rich combustion, therefore, the combustor model for rich fuel atmosphere was established. Additionally, models were created for the other components of the turbine which work on the same gases. Another model was created for the components of two configurations of ammonia water mixture (kalina) cycle. As integrated to the combined cycle power plant, the optimization strategy considered for these configurations is for them to be powered by the exhaust gases from either the gas turbine or the gases leaving the Rankine boiler (HRSG). This included ChGT regarding its performance and its environmental characteristics. The previously considered combined configuration is integrated by as single and double effect configurations of an ammonia water absorption cooling system (AWACS) for compressor inlet air cooling. Both were investigated and designed for optimizing the triple combination power cycle described above. During this research, tens of functions were constructed using VBA to look up tables linked to either estimating fluids' thermodynamic properties, or to determine a number of parameters regarding the performance of several components. New and very interesting results were obtained, which show the impact of the input parameters of the individual cycles on the performance parameters of a certain combined plant’s cycle. The optimized parameters are of a great practical influence on the application and running condition of the real combined plants. Such influence manifested itself in higher rate of heat recovery, higher combined plant thermal efficiency from those of the individual plants, less harmful emission, better fuel economy and higher power output. Lastly, it could be claimed that various concluding remarks drawn from the current study could help to improve the understanding of the behaviour of the combined cycle and help power plant designers to reduce the time, effort and cost of prototyping.
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Kochar, Yash N. "Laminar flame speed and stretch sensitivity of hydrocarbon fuels at high preheat, pressure and vitiation." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52216.
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This thesis investigates the laminar flame speed of C₁-C₃ alkanes and their binary mixtures at conditions of interest in natural gas based gas turbines viz. high temperature, pressure and dilution. Laminar flame speed has been found useful not only for validating chemical kinetics mechanisms but also for developing empirical scaling laws for practical combustion systems. The thesis addresses the lack of laminar flame speed data of C₁-C₃ alkanes at preheat (300-650 K), pressure (1-10 atm) and significant oxidizer dilution (15-21 vol% O₂). Over 400 measurements are reported over a wide range of conditions along with comparison to predictions from leading chemical mechanisms. Unstretched flame speed measurements were performed using a modified Bunsen flame technique based on reaction zone area from chemiluminescence imaging, whereas the strain sensitivity measurements were performed using a bluff-body stabilized stagnation flame with high resolution PIV. These measurements are used to: (i) discern the uncertainties associated with the measurements, (ii) understand the effect of fuel mixture and vitiation on flame speed, and (iii) validate the performance of the leading chemical kinetics mechanisms. Extensive testing shows the unstretched flame speed measurements from the modified Bunsen technique are reasonably accurate. Vitiation studies for methane and propane flames at high preheat show the reduction in flame speed results primarily from the thermal effect of the diluent and that the relative change in flame speed from the undiluted mixture is well correlated to the fractional change in the adiabatic flame temperature over a range of conditions. Significant difference in the measured and predicted flame speeds were observed for rich, atmospheric pressure, propane and lean, high pressure, methane/ethane mixtures with dilution. This highlights possible avenues for improvements in the chemical kinetics mechanisms. Systematic errors were also identified in the Bunsen flame measurements at certain conditions, such as for rich flames with dilution, indicating a need for better understanding of the Bunsen flame technique at these conditions. The difference in the measured and predicted flame speed does not show any clear correlation with the flame height or the strain sensitivity of the mixture. Finally previously proposed mixing rules for estimating flame speed of fuel mixtures from pure fuel components are shown to be reasonably accurate over a range of pressure, reactant temperature and dilution conditions.
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Nilsson, Martin. "Expansionsmaskiner istället för strypventiler - en effektivisering." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-146322.
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In Uppsala CHP Plant, there are six pressure reducing valves to reduce the pressure from 15 to 3 bars, before six absorption heat pumps. During the process the energy is conserved but losses occur in form of exergy. The aim of this thesis is to reduce the losses of exergy. This can be done by letting turbines replace the pressure reducing valves. In this thesis an investigation has been done of the conditions today, the conditions after the change from pressure reducing valves to turbines and a comparison of three different types of turbine solutions. The three examined solutions are one turbine, several helical screw expanders and several small turbines in parallel with asynchronous generators. The six absorption heat pumps have been divided into two groups; one group of four and one group of two absorption heat pumps. An investigation of locations and space in nearby switchgears has been done for each group. Contacts with retailers of the examined turbine solutions have been taken to gather technical specifications. These technical specifications have been used to simulate the electricity production and the economical yield of each type of examined solution. The investigation shows that the best solution is the solution with several small turbines with asynchronous generators. It has lower investment cost (15 [MSEK]) and the best yield. The proposed solutions will have an installed capacity of 2.65 [MW] to a cost of 5 601 [SEK/kW]. The electric energy production will be 15.7 [GWh/year]. An investment is recommended to a future electric energy price around 400 [SEK/MWh]. Before an investment it is recommended to investigate how to optimize the regulation of the new system with absorptions heat pumps and turbines.
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Santos, Moisés Teles dos. "Análise exergética dos sistemas térmicos em um processo de produção de celulose e papel." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-12072007-190648/.
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Este trabalho apresenta uma avaliação comparativa de desempenho termodinâmico de sistemas térmicos em uma unidade industrial de fabricação de celulose e papel Kraft. Foram coletados dados de projeto e operação para o sistema atual de utilidades e de um novo sistema em fase de implantação. A análise exergética é utilizada como ferramenta de avaliação quantitativa e qualitativa para os principais componentes do sistema de cogeração de energia: caldeiras de força, caldeiras de recuperação química, turbinas e válvulas redutoras. Diferentes critérios de desempenho globais e relativos são determinados através de balanços simultâneos de energia e entropia (balanços exergéticos). As irreversibilidades ou entropia gerada nos sistemas são determinadas através da exergia destruída. Esta abordagem revela os principais pontos onde a energia é degradada em sua qualidade, indicando onde devem ser buscadas alternativas de otimização termoeconômica para um melhor aproveitamento dos recursos energéticos disponíveis.This work presents a comparative evaluation from thermodynamic performance view of thermal systems in a Kraft pulp and paper mill. The design information and the data of the industrial operation were collected for the current utility system and for the new system that has been buit. The exergy analysis is applied as the quantitative and qualitative evaluation tool for the main energy conversion systems: power boilers, chemical recovery boiler, turbines and throttling valves. Different global and relatives performance criteria are estimated by simultaneous energy and entropy balances (exergy balances). The irreversibility or generated entropy in the systems is determined by the destroyed exergy. This approach reveals the places where energy quality is mainly degraded and shows where alternatives for optimization must be sought for a better use of the available energetic resources.
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Kohut, Vojtěch. "Výroba stlačeného vzduchu v TŽ Třinec." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229816.
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The main purpose of this master’s thesis is description of the current technology of compressed air production in the grounds of Třinecké Železárny, a.s. (TZ). Compressed air for companies in the TZ area is manufactured and distributed by company Energetika Třinec, a.s. (ET). The part of the thesis is the preparation and execution of measurement including evaluation of specific energy consumption for production of compressed air by compressors of ET company. In conclusion there is proposed the possibility of substitution of compressors including the economic evaluation.
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Šimonová, Lucie. "Distribuční soustava Kypru - realizovatelnost obnovitelných zdrojů a přenos energie." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219218.
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Until a few decades ago few people could imagine that the photovoltaic, solar thermal and other power based on renewable resources, will become a reality. Today people from all over the world on the contrary try at full blast derive benefit from of all possible available source. Using sunlight as a source of energy is first enforced only for small devices such as calculators for charging the battery, but now we are able to produced energy from the sun to supply people around the world. Of course it is not possible supply consumer sector plus firm only from performances renewable power supply. Therefore endeavour is derive benefit from classical energy production at the same time with others power supply. The basic components of photovoltaic and solar thermal power are panels. The panels are made of different materials in different shapes and sizes. During production, the resulting effect looks in addition to costs associated with production. For photovoltaic and solar thermal power plant requires sufficient sunlight. The sunshine has biggest intensity on south of ours planets. Therefore endeavour is build lump these power station just in stand with bigger intensity sunshine. One of them is just Cyprus, too.
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Kim, Yong Sung. "Design with Constructal Theory: Steam Generators, Turbines and Heat Exchangers." Diss., 2010. http://hdl.handle.net/10161/2972.
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This dissertation shows that the architecture of steam generators, steam turbines and heat exchangers for power plants can be predicted on the basis of the constructal law. According to constructal theory, the flow architecture emerges such that it provides progressively greater access to its currents. Each chapter shows how constructal theory guides the generation of designs in pursuit of higher performance. Chapter two shows the tube diameters, the number of riser tubes, the water circulation rate and the rate of steam production are determined by maximizing the heat transfer rate from hot gases to riser tubes and minimizing the global flow resistance under the fixed volume constraint. Chapter three shows how the optimal spacing between adjacent tubes, the number of tubes for the downcomer and the riser and the location of the flow reversal for the continuous steam generator are determined by the intersection of asymptotes method, and by minimizing the flow resistance under the fixed volume constraints. Chapter four shows that the mass inventory for steam turbines can be distributed between high pressure and low pressure turbines such that the global performance of the power plant is maximal under the total mass constraint. Chapter five presents the more general configuration of a two-stream heat exchanger with forced convection of the hot side and natural circulation on the cold side. Chapter six demonstrates that segmenting a tube with condensation on the outer surface leads to a smaller thermal resistance, and generates design criteria for the performance of multi-tube designs.
Dissertation
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Tanvir, Hossain Ahmed. "Evaluation of Steam Turbines Triangular Tooth on Stator Labyrinth Seal." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10830.
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Labyrinth seals are often utilized in locations where contact seals cannot be utilized due to the large displacements of the rotating shaft. The performance evaluation of a labyrinth seal is very important to make sure that optimum performance of turbomachinery is attained. Performance parameters such as carryover coefficient, discharge coefficient were evaluated for a see through triangular tooth on stator labyrinth seal. This computational study investigates how flow conditions and seal parameter variations for see through tooth on stator triangular cavity labyrinth seals affect the value of the carryover coefficient and discharge coefficient. A Finite volume CFD commercial code was used to accomplish the above study. The influence of Reynolds number, rotational speed, seal radial clearance, pitch, tooth angle, tooth width are considered using the finite volume method of computational fluid dynamics. It was found that Reynolds number, high shaft speed and clearance have a significant effect on the carryover coefficient and the discharge coefficient. Clearance is the major influential parameter to be considered among all seal geometric parameters to optimize an ideal seal.
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Ayyalasomayajula, Sricharan Kishore. "A numerical study of curved labyrinth seals for steam turbines." 2005. http://etd.utk.edu/2005/AyyalsomayajulaSricharan.pdf.
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Thesis (M.S.) -- University of Tennessee, Knoxville, 2005.Title from title page screen (viewed on January 30, 2006). Thesis advisor: Ahmad D. Vakili. Document formatted into pages (xiii, 99 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 68-72).
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Srivastava, Nischal Ordonez Juan C. "Modeling of solid oxide fuel cell/gas turbine hybrid systems." 2006. http://etd.lib.fsu.edu/theses/available/etd-07102006-234124.
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Thesis (M.S.)--Florida State University, 2006.Advisor: Juan C. Ordonez, Florida State University, College of Engineering, Dept. of Mechanical Engineering. Title and description from dissertation home page (viewed Sept. 15, 2006). Document formatted into pages; contains viii, 78 pages. Includes bibliographical references.
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Saunion, Roland. "Optimization of a multi-level steam distribution system by mixed integer non-linear programming." Thesis, 2001. http://hdl.handle.net/10413/5899.
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The objective of this project is to optimize the SAPREF oil refinery steam distribution in which
imbalances between the various levels presently require the venting of steam from the lowest level. The
overall steam balance shows that the problem originates from an excess of high·pressure (HP) steam
production for too few medium pressure steam users and turbines.
We proposed to solve this problem by considering the replacement of selected steam turbines with
electrical drives. Given a set of demands of electricity, mechanical power and steam at various pressure
levels, the objective is to recommend configuration changes to minimize overall cost. This is not a trivial
problem, as steam not passed down through turbines to lower levels can create a shortage there, so a
combination of replacements is required.
The variables of the problem are both decision variables on every steam turbine and continuous variables,
such as flows and enthalpies. These decision variables are integer variables, 0 or 1 for every steam
turbine. Depending on whether it is kept on steam use or replaced with an electrical drive, these variables
are as follows: E = 0: keep the existing steam turbine
E - 1: switch it to an electrical drive.
A complete and realistic model of this utility section must be constructed in order to represent the actual
distribution accurately. This model will include an objective function to minimize, some equality and
inequality constraints, and some cost functions. If we want this model to be accurate, we shall have to
deal with nonlinearities to avoid simplifications, and these non-linearities could lead to infeasabilities or
sub-optimal solutions. So we are facing a typical MTNLP (Mixed Integer Non-Linear Programming)
problem to find optimal configuration changes which will maximize the return on investment, meeting
the electrical, mechanical and steam demands of the refinery. In order to solve this difficult optimization
problem we shall use the user-friendly package GAMS (General Algebraic Modeling System).Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.
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Nel, Willem Petrus. "Structural integrity assessment of a low pressure turbine with transverse cracking." Thesis, 2009. http://hdl.handle.net/10210/2175.
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M.Ing.This dissertation deals with the structural integrity analysis of a low pressure (LP) turbine with transverse cracking. Cracks are initiated in the centre ring keyway of the shaft by a fretting mechanism and propagate during barring operation. The cracks arrest during normal operation when they are still relatively shallow. The aim of the calculations is to predict the transition where cracks start propagating by high cycle fatigue during normal operation of the shaft. Most influencing factors, including continuum mechanics, mathematical modelling, material behaviour, service loads and industry experience, are studied in detail as a precursor to the case study. The calculated results show that the case study is an example where the application of fracture mechanics on the crack-free stress field leads to erroneous results. There is a significant redistribution of stress in the presence of the crack so that the actual stress ratio, as calculated from three dimensional cracked models, varies significantly compared to the crack-free model. Calculated results, together with carefully researched material properties, confirm the postulated crack growth during barring operation and predict limiting crack sizes where high cycle fatigue would ensue during normal operation. The case study concludes that the shaft has a significant remaining life and that it can be returned to service with periodic non-destructive examinations.