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Dissertations / Theses on the topic 'Steam generators'
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CABRAL, EDUARDO L. L. "Modelo matematico para o estudo do comportamento dinamico de geradores de vapor de tubos em U com circulacao natural." reponame:Repositório Institucional do IPEN, 1985. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9256.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Waite, Jason S. "The application of brush seals to steam turbine generators." Thesis, Northumbria University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367419.
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Rummens, Helena E. C. "The thermalhydraulics of tube-support fouling in nuclear steam generators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/NQ48334.pdf.
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Tulloch, Sam. "The use of dispersants in pressurised water reactor steam generators." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/706/.
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Environmental degradation promoted by the presence of sludge piles in the steam generators of Pressurised Water Reactors (PWR) can pose a threat to their safe and continuous operation. The use of dispersants can reduce the rate at which sludge accumulates. Polyacrylic acid (PAA) is currently the only dispersant used in PWRs. Settling rate tests identified several dispersants with the potential to outperform PAA, notably Hydroxyethylidene-1,1-diphosphonic Acid (HEDP). To estimate the dispersant concentration required during plant operation, optimum concentrations were identified for both PAA and HEDP. Nuclear magnetic resonance spectrometry was used to investigate the thermal stability of HEDP between 230 and 270oC, revealing that HEDP decomposes more rapidly than PAA. The dominant HEDP decomposition product was shown to be orthophosphate but several other long lived intermediate products were detected. The effect of dispersants on the environmental degradation of grade 316 stainless steel was determined by electrochemical methods and by constant extension rate tests. Rates of general corrosion measured by linear polarisation resistance and electrochemical impedance spectroscopy were shown to be very low (on the order 10-5 mm/year) under aerated and deaerated conditions both at room temperature and at 70oC. Corrosion rates were slightly reduced in the presence of PAA and HEDP. Constant extension rate tests demonstrated that neither PAA nor HEDP promote stress corrosion cracking at 250oC. It was concluded HEDP would not be suitable for use in PWRs due to its rapid thermal degradation rate. The decomposition products were shown to rapidly concentrate in steam generators thereby preventing accurate control of water chemistry.
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Rummens, Helena E. C. (Helena Elisabeth Cornelia) Carleton University Dissertation Engineering Mechanical and Aerospace. "The Thermalhydraulics of tube-support fouling in nuclear steam generators." Ottawa, 1999.
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Rehfeldt, Sebastian [Verfasser], and Günter [Akademischer Betreuer] Scheffnecht. "Radiative heat transfer in oxy-fuel steam generators / Sebastian Rehfeldt ; Betreuer: Günter Scheffnecht." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118507487/34.
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Damon, Randolph. "A probabilistic fracture mechanics model for the tubing degradation of the Koeberg steam generators." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/5571.
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Includes bibliographical references (leaves 115-124).The susceptibility of Steam Generator (SG) Tubes (particularly tubes manufactured from Inconel 600) to primary water stress corrosion cracking (PWSCC) has been a major concern to the nuclear industry since 1971, when this phenomenon was first observed outside the laboratory. Since the susceptibility of Inconel 600 to PWSCC in pure water was first established as a certainty, various electricity utilities have devoted considerable resources to determining the exact nature of this degradation phenomenon and to predicting its consequences. Whereas, the study of the nature of this degradation mechanism has led to many conflicting conclusions, the predictive methods developed have been more successful. Initially, the establishment of the Leak Before Risk of Break principle has allowed various utilities to justify SG operation with cracked tubes. Later, the development of probabilistic simulation methods, most notably by EdF and the Jozef Stefan Institute (JSI), have led to further justification of the existing maintenance regimes and also allowed the ability to do sensitivity studies with regards to various influencing parameters. The current maintenance regime at the Koeberg Nuclear Power Station (near Cape Town, South Africa) utilises tube plugging (when cracks exceed a certain length limit) and online leak detection (based on detection of radioactive Nitrogen 16) as the main means of ensuring safe SG operation. However, the plugging limit used is based on a conservative deterministic analysis, which may be penalising in some situations. Thus, the need for risk-based SG life-time optimisation was evident.
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RODRIGUES, LUIZ A. H. "Modelagem teorica-experimental da equacao da quantidade de movimento para geradores de vapor de reatores PWR." reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10391.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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D'Angelo, Ricardo Andres. "The effects of dispersants on the fouling and the blockage deposits in pressurized water reactor steam generators." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066767.
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L’acide polyacrylique (APA) est injecté dans les générateurs vapeurs (GV) des réacteurs à eau sous pression pour limiter leur encrassement et leur colmatage. Le but de cette étude est de déterminer l’action de l’APA sur les dépôts présents dans les GV, et le caractère préventif du dispersant vis-à-vis de la formation de dépôts. Dans un premier temps, des dépôts de magnétite ont été soumis aux conditions rencontrées en phase liquide dans les GV, avec et sans APA en boucle d’essai. La concentration en fer en sortie de la boucle augmente significativement à partir d’une injection de 1 mg.kg-1 d’APA. Quelle que soit la concentration d’APA testée, la caractérisation après essai des échantillons montre une diminution localisée au sommet des octaèdres de magnétite et une couche d’hématite en surface du dépôt. Cependant cette couche a une épaisseur d’autant plus importante que la concentration en APA testée est grande. Dans la seconde partie, l’effet de l’APA sur la formation du dépôt sur un tube type GV a été investigué, dans une boucle simulant les conditions diphasiques des GV. Les résultats montrent une augmentation de la concentration en fer en sortie de la boucle avec l’injection d’APA. Les caractérisations effectuées sur les échantillons ont, par ailleurs, montré une diminution de l’épaisseur de la couche d’oxyde formée et un changement de la magnétite en hématite à l’interface liquide-vapeur. Ces deux études et une étude complémentaire sur la complexation de fer par l’APA à 25oC, ont permis de proposer des hypothèses expliquant le mécanisme d’action de l’APA sur les espèces du ferPolyacrylic acid (PAA), is injected into Pressurized Water Reactor steam generators (SGs) to limit the fouling and the blockage of the SGs units, which decreases thermal performance and increase maintenance costs. The aim of this study is to determine the action mechanism(s), the efficiency and the pre-emptive nature of PAA on the fouling and blockage deposits in SGs. As a first step in this work, magnetite deposits were formed. These deposits were used to investigate the effects of PAA on pre-existing magnetite deposits in a dedicated experimental loop having the physico-chemical conditions of the SGs in liquid flow. Iron concentration at the loop exit increased with the injection of at least 1 mg.kg-1 PAA. Sample characterizations show a localized diminution of the magnetite octahedra peaks at all tested PAA concentrations and the formation of a thicker hematite layer at higher PAA concentrations. This work was followed by the investigation of the effect of PAA on magnetite suspensions and the formation of deposit layers onto the passive layer in the presence of PAA. This was performed in a dedicated biphasic loop having the physico-chemical conditions of SGs. Results indicated an increased iron concentration at the loop exit with the injection of PAA. Characterizations of the samples indicated the apparent diminution of oxide layer thickness and a change in oxide phase from magnetite to hematite at the liquid-vapor interface. The study of these effects and a complexation study performed at 25 oC, led to the formation and proposal of hypotheses to explain the underlying action mechanisms of PAA
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Gerken, Lisa M. "Long-Term Cooling of an SBLOCA: Boron Precipitation in the Core, Boron Dilution in the Steam Generators." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/24906.
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When soluble boron is used to control reactivity, there are two particular events which can challenge long-term core cooling (LTCC) during the small break loss-of-coolant accident (SBLOCA): boron precipitation and boron dilution. The initial consequences of the SBLOCA are mitigated by the emergency safety systems, but the core continues to boil. As boron is less volatile than steam, the steam is virtually boron free. All the boron remains in the core, the boron concentration in the core rises. If the solubility limit is reached, precipitation could occur. The boron precipitation event was historically considered to be bounded by the large break accident. However, there are characteristics of the SBLOCA which cannot be neglected and an SBLOCA specific methodology is required. On the opposite end of the boron concentration spectrum is the SBLOCA boron dilution event. The steam generators remove heat from the primary and condense the steam. The condensation of the boron-free steam can result in the accumulation of a deborated slug of water. If natural circulation restarts, the slug can be transported toward the core and potentially reduce the core boron concentration enough to induce a recriticality.
This thesis describes two analytical methodologies for these SBLOCA LTCC events. The two methodologies have a similar approach. Both use transient system analyses for inputs to and justification of the follow-on boron concentration calculations. For boron precipitation, a maximized concentration is calculated with the Small Break Boron Precipitation model. For boron dilution, a minimized core inlet concentration is calculated using computational fluid dynamics.Master of Science
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Watson, Bond. "A protocol for evaluating thermal performance of 14 solar steam generators for the Kogan Creek solar boost project." Thesis, Watson, Bond (2012) A protocol for evaluating thermal performance of 14 solar steam generators for the Kogan Creek solar boost project. Masters by Coursework thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/17326/.
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The Kogan Creek Solar Boost is a world-first commercial project that sees AREVA Solar designing, supplying and constructing CLFR-based solar steam generators for CS Energy, a major power generation company in Queensland, Australia. Part of the requirements of the Project is that AREVA Solar must performance test the technology and prove that it will produce the energy required with known solar radiation input.
In this dissertation, the current research in performance modelling, simulation, validation and testing of CLFR technology will be explored as a means to provide a guideline for developing a test protocol for the Kogan Creek Solar Boost Project. There were significant publications in the area of performance modelling, simulation and (sometimes) validation of mathematical models for CLFR receivers and reflectors. In the area of validating mathematical models of actual CLFR technology, the area is not well published; performance testing of CLFR projects is further scarce. Only one technical standard exists for developing test protocol, however, this imposes limitations and does not allow for working-fluid phase-change processes. Guidelines for developing test protocol are scant, with only the NREL having published their interim work for performance testing of parabolic trough solar fields.
Through combining the results of the CLFR mathematical modelling and the NREL parabolic trough performance acceptance testing guidelines, a guideline for CLFR can be developed and this is presented in this Dissertation. There is still considerable work in this area, and this is evidenced by the formation of an ASME Committee that is to develop a Performance Test Code as a definitive technical standard for all solar thermal technologies over the coming years. In the interim, in lieu of the availability of technical standards, the results from this Dissertation can inform and guide the development of a test protocol for the solar steam generators to be installed on the Kogan Creek Solar Boost Project.
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Yang, Guangze. "Investigations of the Tube Support Plate (TSP) clogging phenomenon in PWR steam generators - understanding and prioritization of its formation mechanisms." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066441/document.
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Le générateur de vapeur est un composant essentiel du réacteur à eau pressurisée. Après 15 à 20 ans de fonctionnement du GV, un phénomène de colmatage est observé, qui induit le bouchage du passage folié entre les tubes GV et la plaque entretoise. Ce phénomène peut avoir de graves conséquences pour le fonctionnement de la centrale nucléaire. L’objectif majeur de cette thèse est d’approfondir les connaissances des mécanismes responsables de la formation du colmatage en identifiant et hiérarchisant les processus prépondérants. L’installation COLENTEC est un outil expérimental conçu pour reproduire des dépôts dans des conditions représentatives d’un GV. La post-caractérisation microscopique a permis d’identifier la contribution du phénomène de précipitation et le rôle d’initiation de la passivation du matériau. Les formes spécifiques du colmatage, lipping à l’entrée et rides le long de la plaque entretoise, n’ont pas été observées dans les essais COLENTEC. Cela peut être provoqué par l’absence de particules dans la section d’essai ou une vitesse insuffisante du fluide. Le flashing et le phénomène électrocinétique ont été supposés contribuer à la formation du colmatage. Une collaboration avec l’Université de Manchester a été établie au cours de ce travail afin d’étudier expérimentalement le phénomène électrocinétique. Les travaux effectués ont permis de mieux comprendre ce phénomène et de suggérer son influence considérable dans la formation du colmatage. Des quantifications numériques de chaque phénomène ont été réalisées, prédisant un rôle prédominant du phénomène électrocinétiqueThe steam generator is an essential component in PWR. After 15-20 years of functioning, an obstruction by deposits of flow holes between Tube Support Plate (TSP) and primary tubes is observed, called TSP clogging. This phenomenon may lead to dramatic consequences for nuclear power plant operation. The aim of this thesis is to deepen the understanding of the mechanisms responsible for TSP clogging by identifying and prioritizing the preponderant processes. COLENTEC is an experimental facility designed to reproduce TSP clogging deposits under representative conditions. Microscopic characterizations allowed revealing the deposit formation by precipitation and the initiation role of material passivation in deposit formation. Lipping and ripple forms, specifying TSP clogging, were not observed in COLENTEC tests. This is suggested to be caused by insufficient concentration of suitable particles at the test section. Particle deposition is supposed to be essential for the formation of lipping deposits. Electrokinetic and flashing phenomena are supposed to contribute to TSP clogging formation. An experimental collaboration with the University of Manchester was established to better understand the clogging formation by investigating the role of electrokinetic phenomenon. This study allowed reforming deposits with lipping and ripple forms as observed in EDF steam generators. Electrokinetic involvement, strongly affected by flow velocity, was considerably suggested in TSP clogging formation. Numerical quantification of deposit formation by each phenomenon was performed and compared to EDF feedbacks. Electrokinetic phenomenon was found to play a predominant role
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Balitski, A., J. Eliash, and V. Balitska. "Low and high cycle fatigue of resistant steels and nickel based alloys in hydrogen for gas, steam turbines and generators applications." Thesis, 12 International Fatigue Congress “FATIGUE-2018”. Poitiers, Futuroscope, France. May27- June 1, 2018, 2018. http://hdl.handle.net/123456789/5002.
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Rezaie, Navaie Ali [Verfasser], George [Akademischer Betreuer] Tsatsaronis, George [Gutachter] Tsatsaronis, and Udo [Gutachter] Hellwig. "Thermal design and optimization of heat recovery steam generators and waste heat boilers / Ali Rezaie Navaie ; Gutachter: George Tsatsaronis, Udo Hellwig ; Betreuer: George Tsatsaronis." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156187052/34.
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LOPEZ, LUIZ A. N. M. "Transformadas de Wavelets e logica Fuzzi na inspecao por Eddy-Current em tubos de geradores de vapor de centrais nucleares." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11012.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Loubser, Karl Albie. "An experimental study of an inherently-safe, natural circulating, flash-tube type system for a nuclear reactor steam supply concept." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96050.
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Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: This project investigates aspects of a novel inherently safe nuclear power steam supply system as safety is of paramount importance. The system envisaged has unique features namely: a) a two-phase flow flash-tube type natural circulating primary loop (also the secondary radioactive particle containment); b) a twophase flow thermosyphon heat pipe type heat exchanger secondary loop is used to transfer heat from the primary loop to the steam generators, thereby physically separating the two flow streams from one another; c) a natural convection air cooled condenser for the removal of the reactor’s residual heat; d) a unique core using TRISO type fuel (acting as the primary radioactive particle containment) with life of at least 8.9 years; e) a steel containment vessel acting as a tertiary radioactive product containment; f) a concrete containing structure with air vents to allow air to pass over the main steel containment vessel for cooling purposes in the case of an emergency, and for the removal of parasitic heat during operation. In particular the primary and secondary loops of the proposed system are investigated. This is done by design, construction and testing of a small scale experimental set-up of the primary and secondary loops as well as the development of theoretical models for the two loops. A literature survey focusing on nuclear technology, thermosyphon loops, natural circulating loop instabilities, heat pipes, and two-phase flow modelling is presented to give a brief overview of the technologies as well as tools used in the work undertaken. Observations of the inside flow behaviour of the primary loop experimental set-up were made possible by windows providing many insights into the inner workings, such as plume formation and geysering. The transient response of the secondary heat pipe loop start-up is also investigated. A thermal resistance theoretical model was developed for the secondary loop using heat transfer formulae from theory as well as experimentally semiempirical correlated formula. Different states of operation of the secondary loop were observed during testing with the theoretical model of the condensing regime correlating well, two-phase regime correlating acceptably and liquid regime correlating poorly to experimental results and thus were modelled using an experimentally determined overall heat transfer coefficient. The secondary loop model of the liquid regime is coupled with the primary loop theoretical model to predict the system’s performance. A homogeneous, one-dimensional, simple theoretical model for the primary loop was derived and computer simulated. The results did not compare well with experimental results for single phase flow and failed to capture the onset of two-phase flow. The assumptions of one dimensional model with a unidirectional flow, a hydrostatic pressure problem, a constant volumetric flow rate and the inability of the implementation of the code to handle expansion are noted as some of the flaws in the theoretical model. The following recommendations are made: a more advanced design of the pressuriser should be incorporated into the experiment; the secondary loop’s theoretical model should be characterised under a broader set of operating conditions; the computer program can be used as the basis for further research and implementation of alternative solution algorithms and models.
AFRIKKANSE OPSOMMING: Hierdie projek ondersoek aspekte van ’n ongewone, essensieel veilige kernkrag stoomtoevoer-stelsel, omdat veiligheid van kardinale belang is. Die stelsel wat voorgestel is, het unieke eienskappe, naamlik: a) ’n twee-fasevloei flits-buistipe natuurlik sirkulerende primêre lus (wat ook die sekondêre inperking van radioaktiewe materiaal bevat); b) ’n twee-fasevloei termo-heweleffek sekondêre lus hitte-pyp hitte-uitruiler word gebruik om die hitte vanaf die primêre lus oor te dra na die stoomkragopwekkers en daardeur word die twee strome se vloei fisies geskei van mekaar; c) ’n natuurlike konveksie lugverkoelde kondensor word gebruik vir die verwydering van die reaktors se oortollige hitte; d) ’n unieke kern gebruik TRISO-tipe brandstof (wat as die primêre inperking van radioaktiewe materiaal optree) met ’n lewe van minstens 8.9 jaar; e) ’n inperkingshouer van staal wat optree as ’n tersiêre radioaktiewe produkhouer; f) ’n betonstruktuur met lugventilasie om toe te laat dat lug oor die hoof staalhouer vloei vir verkoeling in ’n noodgeval, en vir die verwydering van parasitiese hitte tydens werking. Hoofsaaklik word die primêre en sekondêre lusse van die voorgestelde stelsel ondersoek. Dit word gedoen deur die ontwerp, konstruksie en die toets van ’n eksperimentele opstelling van die primêre en sekondêre lusse op klein skaal, sowel as die ontwikkeling van teoretiese modelle vir die twee lusse. ’n Literatuurstudie wat fokus op kerntegnologie, termo-heweleffeklusse, natuurlik sirkulerende lus instabiliteit, hitte-pype, en twee-fase vloeimodellering word aangebied om ’n kort oorsig te gee van die tegnologie, sowel as gereedskap gebruik in die werk wat onderneem is. Om die interne vloeigedrag van die primêre lus se eksperimentele opstelling waar te neem, word daar gebruik gemaak van vensters wat dien as ’n manier om die innerlike werking van die proses soos pluimvorming en die kook van die water in die warmwaterkolom te toon. Die oorgangsreaksie van die sekondêre hittepyplus aanvangs is ook ondersoek. ’n Teoretiese termiese weerstandmodel is ontwikkel vir die sekondêre lus met behulp van hitte-oordragformules waarvoor hitte-oordragteorie gebruik is, wat met eksperimentele semi-empiriese formules gekorreleer is. Verskillende toestande van die sekondêre lus se werking is waargeneem gedurende die toetse. Die teoretiese model het goed met die kondensasiestaat gekorreleer, terwyl by die twee-fasewerkswyse aanvaarbare korrellasies aangetref is en die uiteindelike vloeitoestand swakker gekorrelleer het met eksperimentele resultate en dus gemodelleer is met behulp van die NTU-effektiwiteitsmetode. Die sekondêre lusmodel van die vloeistoftoestand is gekoppel met die primêre lus teoretiese model om die werking van die stelsels te voorspel. ’n Homogene een-dimensionele eenvoudige teoretiese model van die primêre lus is afgelei en ’n rekenaar simulasie is uitgevoer. Die resultate vergelyk nie goed met die eksperimentele resultate vir enkelfasevloei en kon nie die aanvang van twee-fasevloei beskryf nie. Die aannemings van ’n een-dimensionele model met eenrigting vloei, ’n hidrostatiese druk probleem, ’n konstant volumetries vloeitempo en die onvermoë van die implementering van die kode om uitbreiding te hanteer is bekend as ’n paar van die foute in die teoretiese model. Die volgende aanbevelings word gemaak: ’n meer gevorderde ontwerp van drukreëlaar moet in die eksperiment ingesluit word; die sekondêre lus se teoretiese model moet gekenmerk word onder ’n wyer stel bedryfsomstandighede, en die rekenaar program kan gebruik word as die basis vir verdere navorsing en die implementering van alternatiewe algoritmes en modelle.
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MESQUITA, ROBERTO N. de. "Classificação de defeitos em tubos de gerador de vapor de plantas nucleares utilizando mapas auto-organizáveis." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11640.
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Tese (Doutoramento)
IPEN/T
Escola Politecnica, Universidade de São Paulo - POLI/USP
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HIPOLITO, FABIO C. "Avaliação das metodologias de análise de sistemas de tubulações de vapor sujeitas a carregamentos do tipo Steam Hammer." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26938.
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Carregamentos transientes termo hidráulicos do tipo Steam Hammer são eventos comuns em sistemas de tubulações de vapor com grandes potenciais de catástrofes em plantas de geração de energia. Uma vez iniciado o evento, ondas de pressões são geradas com amplitudes, geralmente, de grande magnitude ocasionando altas pressões no sistema, ruídos, deformações, fadiga, com possibilidade de danos materiais e econômicos e em casos extremos fatalidades. Os procedimentos da indústria para análise deste tipo de sistema consistem realização de análises estáticas equivalentes ou análise de espectro de resposta com carregamentos caracterizados por meio de métodos analíticos baseados em hipóteses simplificadoras do fluido e fluxo. Neste trabalho é proposta a analise de sistema de tubulações por meio do método de integração numérica com superposição modal e carregamento caracterizado por método numérico com base no método das características. Comparações foram efetuadas entre os resultados obtidos pela metodologia proposta e os procedimentos da indústria, demonstrando que, dado ao alto grau de conservadorismo, os procedimentos da indústria acarretam em superdimensionamento de estruturas e tubulações ocasionando custos adicionais de projeto, sendo a otimização do projeto obtida aplicando-se a metodologia proposta no trabalho.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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SILVEIRA, HELVECIO C. K. da. "Analise de integridade estrutural de tubos de geradores de vapor deteriorados por corrosao sob tensao pelo primario na regiao de transicao de expansao junto ao espelho." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11035.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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FORMIGONI, ANDRE L. "Análise de defeitos em tubos de geradores de vapor de usinas nucleares utilizando a transformada de Hilbert-Huang em sinais de inspeção por correntes parasitas." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10135.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Gomes, Ricardo Antonio do Espirito Santo. "Modelagem computacional de caldeiras de recuperação termica." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265345.
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Orientador: Jorge Isaias Llagostera BeltranDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho faz a análise de caldeiras de recuperação térmica aquotubular no ponto de projeto e fora de projeto, seja ela parte integrante de uma central termoeléctrica de ciclo combinado ou de plantas de cogeração. Os mecanismos de troca de calor, que conduzem à produção de vapor na caldeira, encontram-se parametrizados num sistema matemático baseado nas leis fundamentais da termodinâmica e da transferência de calor, aplicado a um programa computacional. O programa foi desenvolvido no ambiente do software Engineering Equation Solver -EES. Quatro configurações básicas foram estudadas, considerando caldeiras com um e dois níveis de pressão e a variação de parâmetros relevantes. O modelo computacional desenvolvido, caracteriza-se pela sua flexibilidade já que os fatores geométricos da caldeira não precisão ser avaliados. Eventos operacionais como a queima auxiliar e o controle da temperatura do vapor, também podem ser avaliados, para todas as configurações disponíveis. Através das estruturas com dois níveis de pressão é possível evidenciar como a energia recuperada pode ser maximizada redistribuindo as superfícies de aquecimento. Esta analise é realiza para diversos casos, simulada com dados publicados, para sistemas reais e sistemas em estudo, contemplando desta forma cenários operacionais, que poderão esta de acordo com a realidade de qualquer unidade industrial
Abstract: The objective of this work was to model thermal recovery water tube boilers in the design and off-design point, either it has left integrant of a thermoelectric central office of agreed cycle or cogeneration plants. The heat exchange mechanisms, that lead to the steam production in the boiler, meet parameterizations in a based mathematical system in the thermodynamics and the heat transference basic laws, applied to a computational program. The program was developed in the environment of software Engineering Equation Solver - EES. Four basic configurations had been studied, considering boilers with one and two pressure levels and the excellent parameter variation. The developed computational model is characterized for its flexibility, since the steam generators geometric factors no is evaluated. Operational events as the burning auxiliary and the control of the temperature of the steam also can be evaluated for all the available configurations. Through the structures with two levels of pressure it is possible evidences as the recouped energy can be maximized reconfiguring the heating surfaces. This analyzes is carries through for diverse cases, simulated with data published, for real systems and systems in study, contemplating of this form operational scenes, that will be able this in accordance with the reality of any industrial unit
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Kissler, Martin. "Modernizace Jaderné elektrárny Dukovany." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231807.
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Thesis focuses on a detailed technical description of all important parts of secondary circuit in Dukovany power plant and its connection to other systems of power plant. In thesis are analyzed significant adjustments which have been made during the entire operation of power plant including in particular the actions associated with project called Utilization of project reserves of units EDU. In the main part of the thesis were carried out calculations of the power plant's power for states before and after the modernization and there is also analyzed the impact of individual changes on the whole power plant. These changes are with the entire secondary circuit drawn in the T-s diagram.
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Silva, Júnior Cesar Augusto Arezo [UNESP]. "Concepção e análise técnico-econômica da recuperação de calor em sistemas de despoeiramento de aciarias elétricas para geração de vapor superaquecido." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/148018.
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As usinas siderúrgicas caracterizam-se, sob o ponto de vista energético, pela grande intensidade de energia empregada em processos de redução do minério de ferro, fusão das matérias-primas e refino do aço líquido obtido. Quanto aos processos utilizados para a produção de aço, destacam-se o emprego de duas rotas tecnológicas: usinas integradas e semi-integradas (mini-mills). As usinas integradas possibilitam a redução do minério de ferro até ferro-gusa e, a partir deste, a obtenção do aço. As mini-mills caracterizam-se pelo emprego de sucatas metálicas, ferro-gusa ou ferro esponja como matérias-primas e pela obtenção, como produtos, de diferentes tipos de aço. Na operação de refino do aço líquido produzido comumente é necessário o emprego de desgaseificadores a vácuo para remoção de contaminantes e, consequentemente, atendimento às especificações do produto acabado. Com isso, as mini-mills demandam potência elétrica para os processos de fusão do aço e vapor superaquecido para obtenção de vácuo nos ejetores do processo de desgaseificação. Para atendimento a legislações ambientais, sistemas de despoeiramento devem ser aplicados às aciarias, disponibilizando grandes vazões de gases quentes provenientes do forno elétrico. A operação do sistema de despoeiramento indica expressivo potencial para recuperação de calor em processos siderúrgicos. Na presente dissertação propõe-se a coleta e análise de dados de operação do sistema de despoeiramento de um forno elétrico a arco de uma mini-mill brasileira, visando concepção e análise técnica-econômica de uma central de cogeração associada à recuperação de calor destes gases do sistema de despoeiramento
The steel industry can be characterized by its high demand of energy in the process of reduction and production of pig iron and steel. For the production of steel the following routes can be highlighted: integrated plants and mini-mills. Integrated plants are used for production steel from iron ore, allowing the reduction of iron ore until pig iron, and pig iron to steel. Mini-mills are used for production of steel through metallic scraps and pig iron. In a mini-mill, the transformation of metallic scraps and pig iron to steel is reached in melting shop areas. The melting shop areas adopt vacuum degassers as a commonly equipment to remove contaminants of liquid steel and consequently reach requirements of finished products. As a consequence, in a melting shop, electricity is applied in electric arc furnaces and overheated steam is applied in vacuum degassers. According to environmental restrictions these melting shops are integrated with dust collectors. The dust collected in electric arc furnaces has great amount of energy and can express a high potential to heat recovering systems. The present dissertation has purpose in collect and analyzes data from an electric arc furnace with a dust collector in a Brazilian mini-mill for developing a thermal-economic analysis of a cogeneration plant integrated in this mini-mill.
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Goujon, Christophe. "Conséquences des nettoyages chimiques sur la réactivité de la surface externe des tubes de générateurs de vapeur des centrales nucléaires à réacteur à eau sous pression." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066723.
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Les phénomènes d’encrassement et de colmatage des Générateurs de Vapeur (GV), essentiellement par la magnétite, constituent des enjeux majeurs pour la sureté et la performance des centrales nucléaires à réacteurs à eau sous pression. Ils ont pour origine principale la corrosion des tuyauteries en acier au carbone du poste d’eau du circuit secondaire. Depuis 2006, la stratégie de maintenance à long terme des GV du Parc nucléaire français repose sur l’application de nettoyages chimiques. Ce travail a pour objectif d’étudier l’effet des nettoyages chimiques sur la réactivité de la surface externe des tubes de GV des centrales REP. L’étude expérimentale s’est d’abord concentrée sur la synthèse de dépôts de magnétite, par voie électrochimique et hydrothermale, aboutissant à la formation de dépôts encrassants aux propriétés contrôlées. Parallèlement, l’encrassement des tubes de GV a été étudié in-situ sur la boucle d’essais FORTRAND (FORmation et Transport des Dépôts) par la reproduction des conditions physico-chimiques de corrosion-érosion du poste d’eau et des conditions représentatives de formation de dépôts dans les GV. Au préalable, l’oxydation des tubes a assuré la formation d’une couche de passivation en surface. Suite à l’encrassement, les caractérisations de surface indiquent la formation d’un dépôt encrassant de magnétite parfaitement recouvrant et dense. L’étude de l’effet des nettoyages chimiques a ensuite été réalisée dans la boucle d’essais spécifique ECCLIPS, conçue et construite dans le cadre de l’étude. La reproduction des procédés de nettoyages chimiques selon les conditions d’applications en vigueur sur le Parc français conduit à la dissolution pratiquement totale des dépôts encrassants. La conservation de la structure et de la composition de la couche de passivation confirme l’innocuité globale des procédés pour les tubes de GV. Enfin, le réencrassement des tubes nettoyés confirme l’absence d’effet des nettoyages sur la cinétique de formation des dépôts à court terme, donnée importante en vue de définir une fréquence de nettoyage des GV. A court terme, la différence de morphologie des dépôts réencrassants semble induire une porosité plus importante susceptible d’influer sur les performances thermiques des GV. A long terme, l’application plus régulière des nettoyages chimiques devrait limiter la densification des dépôts, particulièrement néfaste pour le transfert thermique, et donc produire des effets bénéfiques sur l’évolution des performances des GVIn the secondary circuit of nuclear Pressurized Water Reactors, magnetite (Fe3O4) deposits lead to Steam Generator (SG) fouling, decreasing the thermal performance and possibly enhancing the risk of SG tube cracking. As a counteraction, chemical cleanings have become the primary strategy to remove oxide deposits in SGs of the EDF fleet. The aim of this study is to investigate the effect of chemical cleaning on SG tubes surface reactivity. First, an electrochemical study was performed to deposit magnetite on substrates made of Inconel 600 and 690 (SG tubes materials). Thermodynamic calculations, voltamperometric studies and deposit characterizations were performed to define the experimental protocol. Magnetite films with a thickness up to several dozen on micrometers were grown by cathodic electrodeposition. Then, SG tubes were fouled in a specific experimental loop, FORTRAND. In this device, magnetite and soluble iron were formed and released in solution by carbon steel pipes corrosion in feedwater circuit representative conditions. Then, corrosion products were flow-carried to the autoclave where their precipitation and deposition on heated SG tubes led to tubes fouling. To reproduce surface characteristics of SG tubes surface, a static oxidation step was first performed in FORTRAND autoclave and result in the formation of a fully covering passive layer on the SG tubes surface.Then in-situ fouling test was done by recirculation in FORTRAND test loop. The magnetite deposit formed on tubes was composed of a dense layer of small crystals. Second, chemical cleaning processes were applied on fouled substrates and tubes in a specific experimental device ECCLIPS designed for this purpose. SG industrial cleaning processes timing and thermochemical conditions were strictly respected during these operations and lead to the dissolution of most of the fouling deposit. The passive layer was still covering the whole surface of the tube and no variation in its thickness or composition was noticed which could indicate that chemical cleaning have no effect on the SG tubes integrity. Finally, cleaned tubes fouling was performed in FORTRAND in the same experimental conditions as before the cleaning test. It could be concluded that there is no effect of chemical cleaning on the fouling kinetics of SG tubes for a short period as the amount of deposit formed before and after cleaning was identical. Nevertheless, the small crystallite dense layer observed before cleaning was not present on cleaned tubes and the size of crystallites were bigger after cleaning. For a short period, this morphology could result in the formation of a fouling deposit with more porosity. As the increase of deposit porosity can impact the thermal transfer at the SG tube surface, morphology changes, hardly predictible, could be important for the SG thermal performance after chemical cleaning. For a longer period, frequent SG cleaning applications should prevent the densification of the deposit and thus delay performance loss over time
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Bradshaw, Jonathan Bernard. "Bit-stream control of doubly fed induction generators." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/14694.
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In recent years rising energy costs and concerns about global climate change have led to the widespread development of renewable electricity generation technology, especially wind generation. The Doubly Fed Induction Generator (DFIG) is commonly used for wind generation applications as it allows for efficient operation of the wind turbine by varying the speed of the generator without resorting to the use of large power converters. A typical DFIG system employs a wound rotor induction generator, with a stator that is directly connected to an external AC grid. The rotor winding is connected to the AC grid via a pair of back-to-back power converters: the Rotor Side Converter (RSC) and Grid Side Converter (GSC). The RSC and GSC require separate vector control systems. Traditionally, these control systems are implemented using microcontrollers, which perform the required control functions sequentially. As the complexity of control algorithms increases to achieve improved functionality and the time available to complete the calculations reduces to keep pace with ever-faster power electronic devices, microprocessor based solutions cannot execute the control program within the available time limit. A potential solution to this performance limitation is the use of hardware based control systems, which can execute control algorithms extremely quickly because many operations are processed in parallel. This is attractive for use in control systems, but implementing hardware control systems is difficult. The designer must either manually translate the control algorithm into individual operations, which are then usually encoded using a Hardware Description Language (HDL), or employ an automated code generation tool. The code is then synthesised and used to program a Field Programmable Gate Array (FPGA). An alternative method for implementing digital control systems is the Bit-Stream control technique. In contrast to the usual methods of implementing digital controllers, Bit-Stream control systems are developed using standard schematic editors provided by FPGA manufacturers. Provided that the desired control functions are available in the Bit-Stream library, the designer need not use HDL to develop the control system. A Bit-Stream based control system for a 2.6 kW DFIG is proposed in this thesis. As previously published research on Bit-Stream control systems focused on scalar control systems only, new Bit-Stream blocks are developed for use in vector control systems. The new vector control blocks include: coordinate transformation units, a Phase Locked Loop (PLL) and a family of modulators which convert Bit-Stream reference signals to gate drive commands for three-phase inverters. A Bit-Stream control system for a 2 kW GSC is developed, simulated and tested experimentally. Elements of this control system are adapted and re-used to develop a Bit-Stream based control system for the RSC of a 2.6 kW DFIG system. These are the first Bit-Stream based vector control systems to be reported in the literature. Supervisory control systems are added to the GSC and RSC to provide closed-loop speed control of the generator speed, soft synchronisation of the generator to the AC grid and operation with unity power factor at the stator terminals of the generator. Control of the DFIG is demonstrated by simulation and experimental testing of a 2.6 kW DFIG system.
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Yanna, Marc-Gabriel. "An investigation of flow-induced vibrations of a steam-generator tube." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07212009-040348/.
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Basset, Marc. "Deposition of magnetite particles onto alloy-800 steam generator tubes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ46232.pdf.
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Basset, Marc. "Deposition of magnetite particles onto alloy-800 steam generator tubes." Thesis, University of New Brunswick, 1998. http://hdl.handle.net/1882/557.
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Uhle, Jennifer Lee. "Boiling heat transfer characteristics of steam generator U-tube fouling." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/17499.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1997.Includes bibliographical references (leaves 109-111).
The boiling heat transfer characteristics of steam generator u-tube fouling deposits were identified by developing a boiling heat transfer model and determining its accuracy through the comparison of calculated and experimental results. Magnetite deposits were fabricated in the laboratory and were characterized using a variety of techniques. Heat transfer measurements were then taken, so that the effect of deposit parameters, including pore size distribution, porosity, permeability and thickness, as well as the effect of mass flux, heat flux and steam quality were investigated. The model predictions were consistent with the experimental results, differing by an average of ±17.5%. Over the range of parameters studied, pore size distribution dominated the deposit heat transfer. It was found that some fabricated deposits improved the heat transfer of the u-tubes, whereas others hindered it. The data were consistent with that of fouled u-tubes pulled from CANDU steam generators. The conditions of the heat transfer measurements and the fabricated deposits were similar to those of US and Canadian steam generators. Therefore, the conclusions drawn in this study are presumed to apply to the steam generators used in the Canadian and US industries.
by Jennifer L. Uhle.
Ph.D.
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Melnyk, Glenn J. "Mechanisms for automated toolhead changing in nuclear steam generator robotics." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06302009-040338/.
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Aranda, Ocampo Brandon Ariel. "Assessment of a compact steam generator aided by computational fluid dynamics." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127310.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 63-65).
Steam generators are an essential component in nuclear power plants which serve to transfer thermal power from a liquid coolant to steam by boiling water. Even with many advancements in the designs of steam generators, they still require extremely large sizes and have high costs which are major hurdles for the implementation of new reactor designs such as Small Modular Reactors. Using a Printed Circuit Heat Exchanger (PCHE) such as those from the company HeatricTM as a steam generator to boil the liquid in the secondary side has potential to overcome the disadvantages of conventional steam generators. Computational Fluid Dynamics was used to aid the assessment of such compact steam generator. The models used were bench marked against a 1-D MATLAB code which simulated a compact steam generator with straight, semi-circular channels. The same conditions were used to simulate a zig-zag, semi-circular PCHE. The zig-zag configuration resulted in a 22 °C increase in superheat over the straight channel configuration at the cost of pressure drops that are over 4 times higher but yet easily accommodated. The PCHE was also simulated in different orientations with respect to gravity and determined there is little advantage in using a vertical layout regarding pressure drop for the zig-zag configuration. Plugging of a single channel was also simulated to determine the effect on surrounding channels and potential hot spots.
by Brandon Ariel Aranda Ocampo.
S.B.
S.B. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
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Clark, Andrew Jordan. "Effectiveness of Surveillance Sampling Strategies for Detecting Steam Generator Tube Degradation." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1435841758.
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Smith, Alan John. "The microstructure and precipitation effects in Inconel alloy 690." Thesis, Sheffield Hallam University, 1990. http://shura.shu.ac.uk/20371/.
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Failure of Alloy 600 steam generator tubing in Pressurised Water Reactors (PWRs) has prompted the investigation of alloy 690 as an alternative material. Six commercially produced tubes and ten experimentally produced alloys have been examined with varying amounts of carbon, aluminium and titanium. Alloy compositions have been selected to investigate the individual and combined effects of these elements on the microstructure and corrosion behaviour in the environments of corrosion tests and simulated PWR conditions. Alloys were subjected to simulated mill annealing treatments at varied temperatures. Microstructural characterisation using optical and electron microscopy has demonstrated the effects of composition and thermal treatment in controlling grain size and carbide precipitation together with the interdependence between these structural details. Stress corrosion resistance of selected alloy 690 tubes has been examined with samples in an autoclave at fixed temperatures with environments based on pure water, sodium hydroxide and sodium hydroxide + sodium sulphate solutions. Susceptibility to intergranular attack has been related to aluminium contents of the alloy and to thermal treatments given. Results suggest a decreased resistance to IGA when aluminium is increased. Thermal treatments given to the samples appear not to be very significant to the amounts of IGA. The compositions and heat treatments used in the corrosion study were further examined on a dedicated scanning transmission electron microscope in order to correlate the effects of, chromium depletion, nickel enrichment and impurity segregation at grain boundaries, with corrosion characteristics. These results have shown the effect of varying the special thermal treatment temperature and time on the degree of enrichment / depletion / segregation and the corrosion resistance of the alloy. The mechanism of protection afforded by the special thermal treatment can thus be elucidated.
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Simpson, Leonie Ruth. "Divide and conquer attacks on shift register based stream ciphers." Thesis, Queensland University of Technology, 2000.
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Horkeby, Kristofer. "Simulation of Heat Recovery Steam Generator in a Combined Cycle Power Plant." Thesis, Linköpings universitet, Institutionen för systemteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75836.
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This thesis covers the modelling of a Heat Recovery Steam Generator (HRSG) in a Combined Cycle Power Plant(CCPP). This kind of power plant has become more and more utilized because of its high efficiency and low emissions. The HRSG plays a central role in the generation of steam using the exhaust heat from the gas turbine. The purpose of the thesis was to develop efficient dynamic models for the physical components in the HRSG using the modelling and simulation software Dymola. The models are then to be used for simulations of a complete CCPP.The main application is to use the complete model to introduce various disturbances and study their consequences inthe different components in the CCPP by analyzing the simulation results. The thesis is a part of an ongoingdevelopment process for the dynamic simulation capabilities offered by the Solution department at SIT AB. First, there is a theoretical explanation of the CCPP components and control system included in the scope of this thesis. Then the development method is described and the top-down approach that was used is explained. The structure and equations used are reported for each of the developed models and a functional description is given. Inorder to ensure that the HRSG model would function in a complete CCPP model, adaptations were made and tuning was performed on the existing surrounding component models in the CCPP. Static verifications of the models are performed by comparison to Siemens in-house software for static calculations. Dynamic verification was partially done, but work remains to guarantee the validity in a wide operating range. As a result of this thesis efficient models for the drum boiler and its control system have been developed. An operational model of a complete CCPP has been built. This was done integrating the developed models during the work with this thesis together with adaptations of already developed models. Steady state for the CCPP model is achieved during simulation and various disturbances can then be introduced and studied. Simulation time for a typical test case is longer than the time limit that has been set, mainly because of the gas turbine model. When using linear functions to approximate the gas turbine start-up curves instead, the simulation finishes within the set simulation time limit of 5 minutes for a typical test case.
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Vytla, Veera Venkata Sunil Kumar. "CFD Modeling of Heat Recovery Steam Generator and its Components Using Fluent." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/336.
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Combined Cycle power plants have recently become a serious alternative for standard coal- and oil-fired power plants because of their high thermal efficiency, environmentally friendly operation, and short time to construct. The combined cycle plant is an integration of the gas turbine and the steam turbine, combining many of the advantages of both thermodynamic cycles using a single fuel. By recovering the heat energy in the gas turbine exhaust and using it to generate steam, the combined cycle leverages the conversion of the fuel energy at a very high efficiency. The heat recovery steam generator forms the backbone of combined cycle plants, providing the link between the gas turbine and the steam turbine. The design of HRSG has historically largely been completed using thermodynamic principles related to the steam path, without much regard to the gas-side of the system. An effort has been made using resources at both UK and Vogt Power International to use computational fluid dynamics (CFD) analysis of the gas-side flow path of the HRSG as an integral tool in the design process. This thesis focuses on how CFD analysis can be used to assess the impact of the gas-side flow on the HRSG performance and identify design modifications to improve the performance. An effort is also made to explore the software capabilities to make the simulation an efficient and accurate.
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PINTO, RAPHAEL GUIMARAES DUARTE. "SIMULATION OF HEAT RECOVERY STEAM GENERATOR OPERATING IN A COMBINED CYCLE PLANT." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=20769@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA evolução das turbinas a gás industriais resultou em um processo de combustão mais eficiente que permitiu a elevação da temperatura dos gases na exaustão dessa máquina. Assim, caldeiras de recuperação de calor cada vez mais complexas foram desenvolvidas com o intuito de aproveitar ao máximo o potencial energético na exaustão das turbinas. Dessa forma, modelos computacionais capazes de prever as condições de operação do equipamento se mostraram necessários de maneira a analisar o comportamento da máquina em diferentes situações, visando à máxima eficiência do processo. Esta dissertação descreve um modelo computacional capaz de simular o funcionamento fora do ponto de projeto, em regime permanente, de uma caldeira de recuperação de calor operando em uma usina de ciclo combinado, enfatizando sua utilização em sistemas de diagnóstico. As rotinas foram desenvolvidas em FORTRAN e os trocadores de calor presentes na HRSG foram modelados individualmente e calibrados através de um sistema de otimização utilizando algoritmos genéticos, responsável por minimizar o desvio do modelo. O programa desenvolvido foi validado contra dados de operação de uma usina real e mostrou resultados satisfatórios, que confirmam a robustez e fidelidade do modelo de simulação.
The heavy duty gas turbines evolution and, consequently, a more efficient combustion process, allowed the temperature rising of the machines’ exhaust gases. Thus, more complex heat recovery steam generators were developed in order to maximize the use of that energy potential. Therefore, computational models capable to predict the operational conditions of the equipment may be needed in order to analyze the machine’s behavior for different situations, in a way to maximize the process efficiency. This thesis describes a computational model able to simulate the off-design behavior of a heat recovery steam generator operation in a combined cycle plant, emphasizing its utilization in diagnostics systems. The routines were developed using FORTRAN, each heat exchanger inside the Heat Recovery Steam Generator (HRSG) was designed individually and the calibration was done by a genetic algorithm responsible for minimizing the model’s deviations. The developed program was validated against operational data from a real plant and showed satisfactory results, confirming the robustness and fidelity of this simulation model.
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Girardon, Hugo. "Shape reconstruction of deposits inside a steam generator using eddy current measurements." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX086.
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Le contrôle non destructif est un outil essentiel pour évaluer la sûreté des infrastructures dans les centrales nucléaires. En particulier, la présence de dépôts conducteurs dans les tubes en U des générateurs de vapeur constitue un enjeu de la sûreté en bloquant le circuit d'eau secondaire. Pour détecter ces dépôts, des sondes à courants de Foucault sont insérées dans les tubes en U pour générer des courants et mesurer en retour un signal d'impédance. Pour inverser ces mesures et reconstruire la forme du dépôt, nous développons une méthode d'optimisation de forme avec descente de gradient régularisée. Du fait du caractère inconnu et possiblement complexe de la géométrie et de la topologie du dépôt, nous nous proposons de le modéliser par le biais d'une fonction level-set. La méthodologie est validée dans un premier temps sur des configurations axisymétriques artificielles et une rapide convergence est assurée par un choix réfléchi des paramètres de régularisation ainsi qu'une adaptation fine des pas de descente. En nous appuyant sur la configuration réelle dans laquelle sont réalisées les mesures expérimentales, nous considérons ensuite une modélisation plus réaliste incorporant la plaque entretoise ainsi que la présence d'imperfections sur la paroi intérieure du tube. Plus précisément, nous utilisons un modèle asymptotique pour prendre en compte ces imperfections et nous les traitons comme de nouvelles inconnues dans notre problème inverse. Une stratégie d'optimisation multi-critères se basant sur l'utilisation de différentes fréquences est ensuite développée pour résoudre le problème. Nous présentons différents résultats numériques sur des tests artificiels ou réels pour montrer la validité de note approche. Nous nous focalisons ensuite sur la transposition du modèle 2D-axisymétrique à des configurations 3D plus génériques. La résolution des équations de Maxwell en présence de courants de Foucault en 3D pose plusieurs problèmes de modélisation de part le choix de la formulation du problème ainsi que des coûts de calculs conséquents à réduire avant de pouvoir élaborer l'algorithme de reconstruction. Avec l'expérience acquise dans la reconstruction en 2D-axisymétrique, nous proposons ensuite une stratégie d'inversion efficace que nous mettons en œuvre sur des données artificielles 3D. La validation des exemples numériques prouve ainsi la faisabilité de l'inversion pour des problèmes de taille conséquente pour des coûts modérés et avec une bonne précision et robustesse par rapport au bruit et aux erreurs de modélisationNon-destructive testing is an essential tool to assess the safety of the facilities within nuclear power plants. In particular, conductive deposits on U-tubes in steam generators constitute a safety issue as they may block the cooling loop. To detect these deposits, eddy-current probes are introduced inside the U-tubes to generate currents and measuring back an impedance signal. We develop a shape optimization technique with regularized gradient descent to invert these measurements and recover the deposit shape. To deal with the unknown geometry, and its possibly complex topological nature, we propose to model it using a level set function.The methodology is first validated on synthetic axisymmetric configurations and fast convergence is ensured by careful adaptation of the gradient steps and regularization parameters. Using the actual domain, from which the acquisitions are made, we then consider a more realistic modeling that incorporates the support plate and the presence of imperfections on the tube interior section. We employ in particular an asymptotic model to take into account these imperfections and treat them as additional unknowns in our inverse problem. A multi-objective optimization strategy, based on the use of different operating frequencies, is then developed to solve this problem. We present various numerical examples with synthetic and experimental data showing the viability of our approach.The focus is then placed on the transposition of the 2D-axisymmetric work to more generic 3D configurations. Solving Maxwell eddy-current equations in 3D raises modeling issues related to the choice of the problem formulation as well as high computational costs that need to be reduced before discussing the reconstruction algorithm. Using the knowledge acquired with 2D-axisymmetric reconstruction, an efficient inversion strategy is then proposed and implemented on 3D synthetic data. Validating numerical examples demonstrate the feasibility of the inversion even for large data at a relatively moderate cost and with good accuracy and robustness with respect to noise and modeling errors
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Beighton, Matthew. "Security analysis of shift-register based keystream generators for stream ciphers." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/236239/1/Matthew%2BBeighton%2BThesis%282%29.pdf.
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Society's thirst for smaller, faster and more complex technology requires highly secure cryptosystems. These systems are under constant pressure to evolve higher levels of security integrated within ever-shrinking, highly complex hardware, with minimal runtime costs. These demands have focused attention on the design of lightweight cryptographic algorithms because of their speed. The research presented in this thesis focuses on the design and security analysis of lightweight stream ciphers capable of authenticated encryption with associated data (AEAD), proposed as part of the National Institute of Standards and Technology's (NIST) lightweight cryptography competition.
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Roupec, Petr. "Analýza přestupu tepla v parogenerátorech bloků VVER 440." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229288.
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The aim of this thesis is to analyze the heat transfer in steam generator of blocks in the nuclear power plant VVER 440. The steam generator represents the border between the primary and the secondary circuit. The heat is carried from a warm water from reactor to a cold water. The steam arises after the heat transfer and drives the steam turbine. An important quantity which represents the heat transfer is a heat transfer factor. This thesis is divided into theoretical and a practical part. In the theoretical part is mentioned a principle of the steam generator and the theoretical calculation of the heat transfer factor, which comes first of all from the character of the streaming in the steam generator. The practical part brings a comparison of the heat transfer factor calculated from data measured after the start of the third block of EDU in 1986, with the heat transfer factor which comes from the measurement after the power-increase for 105 % of nominal power of the same block in 2009. Further is shown the prediction of the heat transfer factor for next power-increase and the following service is shown too.
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Kadáková, Nina. "Návrh paroplynového zdroje elektřiny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417426.
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A combined cycle is one of the thermal cycles used in thermal power plants. It consists of a combination of a gas and a steam turbine, where the waste heat from the gas turbine is used for steam generation in the heat recovery steam generator. The aim of the diploma thesis was the conceptual design of a combined cycle electricity source and the balance calculation of the cycle. The calculation is based on the thermodynamic properties of the substances and the basic knowledge of the Brayton and Rankin-Clausius cycle. The result is the amount and parameters of air, flue gases, and steam/water in individual places and the technological scheme of the source, in which these parameters are listed.
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Collins, Kimberlee C. (Kimberlee Chiyoko). "Computational fluid dynamic (CFD) optimization of microfluidic mixing in a MEMS steam generator." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45770.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 23-24).
The challenge of achieving rapid mixing in microchannels is addressed through a computational fluid dynamics (CFD) study using the ADINA-F finite element program. The study is motivated by the need to design an adequate mixing chamber for aqueous chemical reactants in a micro steam generator. The study focuses on the geometric optimization of a static micromixer channel by considering the trade-off between mixing quality and pressure drop. Both zigzag and straight channels are evaluated, in addition to channels with differing amounts of added obstruction features. Due to computational limits, the numerical analysis is conducted in two dimensions. The results indicate that hydrodynamic focusing of the reactant at the inlet, in addition to the amount and density of added obstruction features, has the most significant impact on mixing efficiency and increased pressure drop. The study presents mixing quality and pressure drop trends that provide useful information for the micro steam generator mixing chamber design.
by Kimberlee C. Collons.
S.B.
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Clark, Randy Raymond. "Modeling Two-Phase Flow in the Downcomer of a Once-Through Steam Generator using RELAP5/MOD2." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76861.
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The purpose of this study is to develop an accurate model of the downcomer of the once-through steam generator (OTSG) developed by Babcock & Wilcox, using RELAP5/MOD2. While the physical model can be easily developed, several parameters are left to be adjusted to optimally model the downcomer and match data that was retrieved in a first-of-a-kind (FOAK) study conducted at Oconee Unit I in Oconee, South Carolina. Once the best-fit set of parameters has been determined, then the model must be tested for power levels exceeding that for which the steam generator was originally designed, so as to determine the power level at which a phenomenon known as flood-back becomes a concern.
All known previous studies that have been conducted using RELAP5/MOD2 have shown that RELAP over-predicts interphase friction. However, all of those studies focused on heated two-phase upflow, whereas the downcomer is modeled as adiabatic two-phase downflow. In this study, it is found that the original slug drag model for RELAP5/MOD2 developed by Idaho National Engineering Laboratory (INEL) under-predicts the interphase friction between the liquid and vapor phase within the downcomer. Using a modified version of the original slug drag model created by Babcock & Wilcox (B&W), an optimum multiplier is found for each power level. An increase of 1181% in interphase friction over the INEL slug drag model, which equals an increase of 4347% for the default B&W model provides the most accurate results for all power levels studied.
Emphasis is also placed on modeling the orifice plate of the OTSG downcomer which has been added to stabilize pressure fluctuations between the downcomer and tube bundle of the OTSG. While several different schemes are explored for modeling the orifice plate, a branch connection with an inlet area 14.22% of that of the downcomer is used to model the orifice plate along with the volume that transitions the two-phase downflow to horizontal flow into the tube nest of the OTSG.
Power levels exceeding that for which the steam generator was designed are tested in RELAP using the slug drag multiplier to determine at which power level a liquid level would occur and would flood-back become a concern. In this study, it is determined that a liquid level would form at 135% power and that at any higher power level, flood-back would be of concern for any user of the steam generator.Master of Science
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Roule, Jaroslav. "Využití biomasy pro získávání elektřiny v ostrovních provozech." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-219913.
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The thesis discusses the use of biomass for electricity island operation. The first chapter explains the concept of biomass and its distribution. It also shows the potential and availability of biomass. The second chapter describes the transformation of biomass into a suitable fuel form. The third to fifth chapter describes the conversion of biomass as a fuel into electrical energy through combustion, Stirling and steam engine. In these chapters there are brought the following parameters and prices of these motors and single-phase and three-phase alternators that can be connected to these engines. Other chapters describe the production of electricity in line with consumption, where the cost per hour to run engines for the various types of fuel and price of the electricity produced in kilowatt hours is calculated. In the last chapter of the thesis there is described the possibility of accumulation of electrical energy.
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Longmire, Pamela. "Computational fluid dynamics (CFD) simulations of aerosol in a u-shaped steam generator tube." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1333.
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Kamboj, Brij Kumar. "Modeling of once-through steam generator thermal-hydraulics during a loss of coolant accident." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16660.
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Sui, Gaoyi. "Some aspects of stress corrosion cracking of Type 316 stainless steel steam generator tubes." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481644.
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Kim, Dohyoung 1970. "Bayesian Belief Network (BBN)-based advisory system development for steam generator replacement project management." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/30011.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2002.Includes bibliographical references (leaves 192-194).
The growing need for improved project management technique points to the usefulness of a knowledge-base advisory system to help project managers understand current and future project status and optimize decisions based upon the project performances. The work here demonstrates the framework of an advisory system with improved ability in project management. Based upon the literature survey and discussion with relevant experts, the Bayesian Belief Network (BBN) approach was selected to model the steam generator replacement proj ect management problem, where the situation holds inherently large uncertainty and complexities, since it has a superior ability to treat complexities, uncertainty management, systematic decision making, inference mechanism, knowledge representation and model modification for newly acquired knowledge. Two modes of advisory system have been constructed. As the first mode, the predictive mode has been developed, which can predict future project performance state probability distributions, assuming no intervening management action. The second mode is the advisory mode, which can identify the optimal action among alternatives based upon the expected net benefit values that are incorporating two important components: 1) expected immediate net benefits at post-action time, and 2) the expected long term benefit (or penalty) at scheduled project completion time. During the work, new indices for important variables have been newly developed for effective and efficient project status monitoring. With application of developed indices to the advisory system, the long term benefit (or penalty) found to be the most important factor in determining the optimal action by the project management during the decision
(cont.) making process and was confirmed by the domain experts. As a result, the effort has been focused on incorporating the long term benefit (or penalty) concept in order to provide more reliable and accurate advice to the project managers. In addition, in order to facilitate the communication between the BBN models and the users, an interface program has been developed using the Visual Basic language.
by Dohyoung Kim.
Sc.D.
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Bujarbarua, Vikram. "Production Optimization Using an In-Situ Steam Generator in a Rejuvenated Heavy Oil Field." Thesis, University of Louisiana at Lafayette, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10003753.
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Steam stimulation is by far the most widely used tertiary oil recovery method. Heavy oil finds its most effective way of production in thermal recovery method. Also with technical effectiveness, steam stimulation brings in cost effectiveness. In-situ steam generation and injection is the most important enhancement to the conventional thermal steam injection technique. Blackbird™ Energy LLC, has developed and a new generation in-situ steam generator with a view to make an almost unproductive heavy oil reservoir in North East Texas to start producing.
In this research, a reservoir simulation study has been performed to history match of pure depletion as well as three months of thermal stimulation done on the reservoir. To mimic the reservoir conditions, Schlumberger Eclipse 300 compositional Simulator has been used. Overall this research performs an evaluation of the newly developed in-situ steam generator capabilities.
The various predictive runs have been made with changing key performance parameters such as location of steam generator and time of application of thermal energy. There has been reported a considerable increase in production of the heavy oil. As a result, in-situ steam injection has been proved to be an effective and environment friendly recovery technique and should be widely considered for replacing conventional steam generators.
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Sethapati, Vivek Venkata. "Computational Fluid Flow Analysis of the Enhanced-Once through Steam generator Auxiliary feedwater system." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/77020.
Full textAbstract:
The once through steam generator (OTSG) is a single pass counter flow heat exchanger in which primary pressurized water from the core is circulated. Main Feedwater is injected in an annular gap on the outer periphery of the steam generator shroud such that it aspirates steam to preheat the feedwater to saturation temperature. An important component of the OTSG and enhanced once through steam generator (EOTSG) is the auxiliary feedwater system (AFW), which is used during accident/transient scenarios to remove residual heat by injecting water through jets along the outer periphery of the heat exchanger core directly on to the tubes at the top of the OTSG. The intention is for the injected water, which is subcooled, to spread into the tube nest and wet as many tubes as possible. In this project, the main objectives were to use first principles Computational Fluid Dynamics to predict the number of wetted tubes versus flow rate in the EOTSG at the AFW injection location above the top tube support plate. To perform the fluid analysis, the losses in the bypass leakage flow and broached hole leakage flow were first quantified and then used to model a 1/8th sector of the EOTSG. Using user defined functions (UDF), the loss coefficients of the leakage flows were implemented on the 1/8th sector of the EOTSG computational model to provide boundary conditions at the bypass flow and leakage flow locations With this method, the number of tubes wetted in the sector of EOTSG for various AFW flow rates was found. Results showed that the number of wetted tubes was in very close agreement to that predicted by experimental-analytical methods by the sponsor, AREVA. With the maximum flow rate of 65 l/s a total of 318 tubes were wetted and the percentage of tubes wetted with broached holes was 8.7%.
The analysis on the bypass leakage flow showed that the loss coefficients was a function of the mass flow rate or the flow Reynolds number through the gap and it increased as the Reynolds number increased from 300 to 1600. The experimental and computational loss coefficients agree to within 15% of each other. In contrast, the constant loss coefficient of 1.3 used by AREVA was much higher than that obtained in this study, particularly in the low Reynolds number range. As the Reynolds number approached 3000, the loss coefficients from this study approached the value of 1.3. This value of the loss coefficient was implemented for the bypass flow leakage in the 1/8th sector of the EOTSG model.
The analysis on the broached hole leakage flow was performed using a single hole, five holes, and one, two, four and eight rows of broached holes in order to characterize the loss coefficients. The one hole and five hole computational models were validated with experiments. The computational models showed the presence of voids in the leakage flow through the tube support plate (TSP), which were not observed (visually) in the experiments. The characterization of the broached hole leakage in the one, two and four rows showed that the loss coefficient of the control broached hole increased as the number of rows increased. These results indicated that for the same height of water on the TSP, the resistance to leakage flow increased as the number of tubes increased. They also indicated that leakage flow through the broached holes was not solely a function of the height of water above the TSP but also the surrounding geometrical topology and the flow characteristics. However, the analysis done for eight rows showed that the loss coefficient became constant after a certain number of rows as the loss coefficient differed by only 5% from the results of the four rows. From these results it was determined that the loss coefficient asymptotes to an estimated value of 4.0 which was implemented in the broached hole leakage flow in the 1/8th sector of the EOTSG.
Computational models of the 1/8th sector of the EOTSG were implemented with the respective loss coefficients for the bypass and leakage flows. Results showed that as the AFW flow rate increased, the percentage wetted tubes increased. The data matched closely with AREVA's experimental-analytical model for flow rates of 14.5 l/s and higher. It was also deduced that complete wetting of the tubes is not possible at the maximum AFW flow rate of 65 l/s.Master of Science