Made available in DSpace on 2014-10-09T12:25:58Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:24Z (GMT). No. of bitstreams: 1 00988.pdf: 3339929 bytes, checksum: 27ead5c2fe041a5b93b6fa5c9a4df73f (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:46:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:44Z (GMT). No. of bitstreams: 1 09057.pdf: 12808764 bytes, checksum: 970b3a8c12068b9ea0e88948bbcda318 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Jorge Isaias Llagostera Beltran / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-13T22:38:51Z (GMT). No. of bitstreams: 1 Gomes_RicardoAntoniodoEspiritoSanto_M.pdf: 2280030 bytes, checksum: 73620817c817b18437fa8219d3244138 (MD5) Previous issue date: 2005 / 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

Around the world, countries are increasingly considering carbon-free energy generation options as the threat of climate change grows. Small modular reactor designs, promising such carbon-free energy generation, are thriving worldwide with novel and innovative technologies that improve safety as well as economic performance. Canada is also considering small modular reactors (SMRs) as a means of achieving net zero carbon emissions by 2050. Some of these reactor designs utilize pressurized water for cooling and moderator. Reactors with pressurized water have been subjected to steam generator tube ruptures in the past, and a detailed investigation into the possible consequences of such incidents in SMRs should be conducted. In this research, a model for one of the newer designs, the NuScale Integrated Small Modular Reactor, was developed with the RELAP5-3D code for assessing safety related transients. The NuScale Small Modular Reactor incorporates helical coil steam generators within its reactor pressure vessel, which are more efficient in terms of heat transfer than the U-tube steam generators that are widely used in nuclear reactors. In the first part of the research, a detailed model is created and used to obtain steady state conditions with parameters collected from NuScale’s Final Safety Analysis Report (FSAR). The Steam Generator Tube Rupture event is analyzed in the second part of the work. Slight differences in the broken and intact steam generator pressures as well as decay heat removal system flow rates are seen in the comparison of reference values and calculated results. Among the reasons for those differences could be that the correlations used by the RELAP5-3D code for heat transfer coefficient and pressure drop in the helical coil steam generators are different than those of the NuScale proprietary code NRELAP5, with which the analyses have been performed in the FSAR. Also, post-dryout heat transfer at the exit of helical coil steam generators and evaporator sections could cause differences in the outlet conditions of the steam, resulting in different mass flow rates as well. The final section of the research simulates a comparable but more severe tube rupture incident without the availability of decay heat removal systems in order to assess the reactor’s emergency core cooling system reaction. Passive decay heat removal systems are crucial components for removing heat after reactor shutdown through heat exchangers that are submerged in the reactor pool and connected to steam generators by a closed loop. The containment pressures, the containment wall temperatures, and the peak fuel clad temperatures are considered to be the key design constraints that must be observed. Future work on this subject could include modifying the source code, adding specific correlations for helical coil steam generators, and comparing the results, as well as quantifying uncertainties in the SGTR event. Main parameters in the quantification of uncertainties would be reactor power, single phase and two-phase discharge coefficients from the break, trip signals and delays as well as break size and location. / Thesis / Master of Applied Science (MASc)

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.

Made available in DSpace on 2014-10-09T12:35:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:55Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:47:15Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:43Z (GMT). No. of bitstreams: 1 07971.pdf: 6425112 bytes, checksum: 2adaba2434371c9ca93a67fa4d783fb9 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by CESAR AUGUSTO AREZO E SILVA JUNIOR null (cesar.arezo@hotmail.com) on 2017-01-10T11:03:30Z No. of bitstreams: 1 Dissertacao_Cesar_Arezo.pdf: 2040140 bytes, checksum: 22ed1c12204c5338583f606a5353e418 (MD5) / Rejected by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido está sem a ficha catalográfica. A versão submetida por você é considerada a versão final da dissertação/tese, portanto não poderá ocorrer qualquer alteração em seu conteúdo após a aprovação. Corrija esta informação e realize uma nova submissão com o arquivo correto. Agradecemos a compreensão. on 2017-01-13T12:08:52Z (GMT) / Submitted by CESAR AUGUSTO AREZO E SILVA JUNIOR null (cesar.arezo@hotmail.com) on 2017-01-16T17:14:48Z No. of bitstreams: 1 Dissertacao_Cesar_Arezo.pdf: 2053752 bytes, checksum: ac3a36225bdb9c284f25c5d8699786ae (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-01-17T15:32:25Z (GMT) No. of bitstreams: 1 silvajunior_caa_me_guara.pdf: 2053752 bytes, checksum: ac3a36225bdb9c284f25c5d8699786ae (MD5) / Made available in DSpace on 2017-01-17T15:32:25Z (GMT). No. of bitstreams: 1 silvajunior_caa_me_guara.pdf: 2053752 bytes, checksum: ac3a36225bdb9c284f25c5d8699786ae (MD5) Previous issue date: 2016-12-16 / 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.

Made available in DSpace on 2014-10-09T12:35:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:55Z (GMT). No. of bitstreams: 0 / Os tubos de Geradores de Vapor em Reatores Nucleares do tipo PWR são submetidos a diferentes níveis de tensões e carregamento em altas temperaturas, reduzindo sua vida útil devido o surgimento de defeitos e corrosão. A inspeção por Correntes Parasitas é um ensaio não destrutivo usado para diagnosticar defeitos de corrosão e descontinuidades na superfície externa e interna em tubos de trocadores de calor. Esses tubos estão sujeitos a danos por diferentes mecanismos de degradação mecânica e química, tais como trincas por fadiga e corrosão sob tensão. Os sinais de inspeção por Correntes Parasitas são afetados por diferentes ruídos dificultando sua análise pelo inspetor. Esse trabalho apresenta os resultados da análise dos sinais de Correntes Parasitas usando a Transformada de Hilbert-Huang (THH) funcionando como filtro de ruídos (De-noising), como uma técnica alternativa de processamento e análise de sinais. A Transformada de Hilbert-Huang teve esse nome atribuído pela agência espacial norte-americana (NASA) para o resultado da reunião de dois processos, um método de decomposição empiricamente modal (Empirical Mode Decomposition EMD), seguido da análise espectral de Hilbert (Hilbert Spectral Analysis HSA). Os sinais de inspeção por correntes parasitas possuem características de transiente, não estacionário e não linear. A transformada de Hilbert-Huang aplicada neste trabalho forneceu dois recursos alternativos em processamento de sinais; o pré-processamento que funcionou como filtro de ruídos, e outro de análise de sinais, responsável pela identificação das características tempo-frequência-energia do sinal. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:47:15Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:43Z (GMT). No. of bitstreams: 1 07971.pdf: 6425112 bytes, checksum: 2adaba2434371c9ca93a67fa4d783fb9 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP