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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Essays in macroeconomics /

Trabandt, Mathias. January 2007 (has links) (PDF)
Humboldt-Univ., Diss (Nicht für den Austausch)--Berlin, 2007.
62

Estimativas do impacto ao Brasil do acordo de facilitação do comércio de Bali

Marinho, Raoni Rugai 11 February 2015 (has links)
Submitted by Raoni Rugai Marinho (raonirmarinho@gmail.com) on 2015-03-11T14:52:13Z No. of bitstreams: 1 Dissertação - RRM_20150311.pdf: 998586 bytes, checksum: 81f50db5cdf96110f5bba72b66357ea4 (MD5) / Approved for entry into archive by Renata de Souza Nascimento (renata.souza@fgv.br) on 2015-03-11T16:25:42Z (GMT) No. of bitstreams: 1 Dissertação - RRM_20150311.pdf: 998586 bytes, checksum: 81f50db5cdf96110f5bba72b66357ea4 (MD5) / Made available in DSpace on 2015-03-11T16:31:51Z (GMT). No. of bitstreams: 1 Dissertação - RRM_20150311.pdf: 998586 bytes, checksum: 81f50db5cdf96110f5bba72b66357ea4 (MD5) Previous issue date: 2015-02-11 / Motivado pelas diversas discussões em torno do futuro das negociações multilaterais do comércio mundial, utilizando o embasamento de trabalhos anteriores realizados a partir de dados de exportação e importação nos Estados Unidos da América, o presente trabalho busca estimar impactos econômicos ao Brasil das diretivas do Acordo de Facilitação de Comércio de Bali, utilizando-se para isso de Modelo de Equilíbrio Geral já consolidado no tratamento de comércio internacional, bem como sua base de dados. Os principais resultados indicam uma reindustrialização das exportações brasileiras, e permitem concluir que a adesão ao Acordo gera ganhos ao Brasil, e que o país segue na direção correta nesse aspecto. Tais resultados se mostram úteis na formulação de futuras diretrizes para a abertura comercial. / Motivated by the various discussions on the future of the multilateral negotiations of world trade, using previous works, which used data on export and import in the United States of America as basis, this paper seeks to estimate the economic impacts of the policies of Bali Trade Facilitation Agreement to Brazil, making use of a consolidated Computable General Equilibrium model in the treatment of international trade, as well as its database. The main results indicate a reindustrialization of Brazilian exports, and show that the adherence to the Agreement generates gains in Brazil, and that the country goes in the right direction in this regard. Such results could be useful in elaborating future guidelines for trade liberalization.
63

Impactos do acordo de preferência comercial transpacífico no agronegócio brasileiro / Impacts of the transpacific trade preference in brazilian agribusiness

Silva, Rodrigo Abbade da 08 February 2017 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work aims to evaluate the impact on Brazilian agribusiness form realization of agreement, Transpacific Trade Preference (TPP). As well as exploring the issue of comparative advantages and complementarity of Brazil's producers markets with the markets of other regions and how it would affect the Brazilian agribusiness. In this sense, we not only analyse the changes in the economy when the elimination of all tariff barriers, what characterizes the formation of a free trade area, but also the elimination of barriers tariff in conjunction with the elimination of the subsidies agreement. To this end, we use the general equilibrium model of Global Trade Analysis Project (GTAP). The Elimination of import tariffs between the economies of the TPP, it was possible to identify the economic impacts on Brazilian agribusiness, mostly, were negative, hurting mainly the sectors of meat, corn, wool, processed food and rice. The fields of wheat, oilseeds and vegetables suffer positive impacts. On the other hand in the scenario of complete liberalisation of trade between the intrablocos regions, such as the Elimination of import tariffs and export subsidies and production. The impacts generated in Brazilian agribusiness were more significant, in the fields of wheat, vegetables, oil seeds and fruits, with the Brazilian agricultural sector producer and exporter being positively influenced. However, wool, milk, processed foods and meats were the hardest hit. In addition, the complete liberalization of trade would promote economic welfare gains and losses higher, when compared to the scenario of tariff elimination, because the tariff structure between members of the TPP is already reasonably reduced. Therefore, the possible intensification in trade intrabloco of TPP, without the reduction of subsidies on production, could weaken the Brazilian agribusiness, therefore suggests loss of competitiveness in the sector. / Este trabalho objetivou avaliar os impactos no agronegócio brasileiro na formação do Acordo de Preferência Comercial Transpacífico (TPP). Nesse sentido, foram analisadas não apenas as mudanças na economia quando ocorre a eliminação de todas as barreiras tarifárias, o que caracteriza a formação de uma área de livre comércio, mas também a eliminação de barreiras tarifárias em conjunto com a eliminação de subsídios entre as regiões do acordo. Para tal, utilizou-se o modelo de Equilíbrio Geral Global Trade Analysis Project (GTAP). Os resultados indicaram, no cenário de eliminação de tarifas de importação entre as economias do TPP, que impactos econômicos no agronegócio brasileiro, na sua maioria, seriam negativos, prejudicando principalmente os setores de carnes, milho, lã, alimentos processados e arroz. Os setores de trigo, sementes oleaginosas e os vegetais sofreriam impactos positivos. Por outro lado, no cenário de liberalização total de comércio entre as regiões intrablocos, como eliminação de tarifas de importação e de subsídios à exportação e produção, os impactos gerados no agronegócio brasileiro seriam mais significativos nos setores de trigo, vegetais, sementes oleaginosas e frutas, com o setor agrícola brasileiro produtor e exportador sendo positivamente influenciado. Porém, os setores lã, leite, alimentos processados e carnes seriam os mais prejudicados. Além disso, a liberalização completa do comércio promoveria perdas econômicas e ganhos de bem-estar maiores, quando comparados ao cenário de eliminação tarifária, pois a estrutura tarifária entre membros do TPP já é razoavelmente reduzida.
64

Impactos dos investimentos no setor energético brasileiro sobre as emissões de CO2: uma abordagem de equilíbrio geral computável

Viana, Jorge Henrique Norões 01 March 2011 (has links)
Made available in DSpace on 2015-05-08T14:44:41Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1758104 bytes, checksum: 44e8e7ad979e645b86ada3465c9bf745 (MD5) Previous issue date: 2011-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study analyses the effects of an increase in investments to energy production, over the emissions of CO2 and the main macroeconomic variables. The data required for their preparation were obtained from the Ministry of Mines and Energy, the IBGE and the Intergovernmental Panel on Climate Change. To meet these goals, the energy inputs were divided into two groups: energy "clean" and "dirty"; based on their coefficients of CO2 emissions in 2006. Then, were simulated scenarios with: increases in investment equivalent to 1% of GDP in 2006, for each energy group, as well as scenarios involving an environmental tax of R$ 100.00 per ton of CO2; for a time horizon of ten years, using a sequential Computable General Equilibrium Model. The results of these simulations showed that there was a direct relationship between increased investments in energy and: the process of capital accumulation, the real GDP growth, the evolution of welfare, the evolution of CO2 emissions and changes in the intensity of CO2 pollution. Meanwhile, the results for simulations involving the environmental tax shown that it implied, in general, in: slowdown in capital accumulation, GDP growth below the steady state, a strong reduction of welfare and increasing reductions of emissions and intensity of pollution. Especially, the combination of an increase in investments for clean energy production, with the adoption of the environmental tax, was able to generate, simultaneously: accelerated accumulation of capital (2,70%) and real GDP growth (1,08%), increase of the welfare (R$ 33 billion) and reduction of the emissions (-1,21%) and intensity of pollution (-2,26%). / Este estudo trata dos efeitos de um aumento dos investimentos destinados a produção de energia, sobre as emissões de CO2 e as principais variáveis macroeconômicas. Os dados necessários à sua elaboração foram obtidos junto ao Ministério de Minas e Energia, ao IBGE e o Intergovernmental Panel on Climate Change. Para cumprir com esses objetivos, os insumos energéticos foram divididos em dois grupos: energéticos limpos e sujos ; com base nos seus coeficientes de emissões de CO2 em 2006. Em seguida, foram simulados cenários com: aumentos nos investimentos equivalentes a 1% do PIB em 2006, para cada grupo de energético; bem como cenários envolvendo um imposto ambiental de R$ 100,00 por tonelada de CO2; para um horizonte de tempo de dez anos, utilizando um Modelo de Equilíbrio Geral Computável sequencial. Os resultados dessas simulações mostraram que existiu uma relação direta entre o aumento dos investimentos em energia e: o processo de acumulação de capital, o crescimento do PIB real, a evolução do bem-estar, a evolução das emissões de CO2 e a evolução da intensidade de poluição por CO2. Enquanto isso, os resultados para as simulações envolvendo o imposto ambiental mostraram que o mesmo implicou, de maneira geral, em: desaceleração do processo de acumulação de capital, crescimento do PIB abaixo do estado estacionário, forte redução do bem-estar e redução crescente das emissões e da intensidade da poluição. Especialmente, a combinação de um aumento dos investimentos destinados a produção de energia limpa, com a adoção do imposto ambiental, foi capaz de gerar, simultaneamente: aceleração da acumulação de capital (2,70%) e crescimento do PIB real (1,08%); aumento do bem-estar (R$ 33 bilhões); e redução das emissões (-1,21%) e da intensidade da poluição (-2,26%).
65

Convergence des impératifs économiques et sociaux des politiques de lutte contre la pauvreté en Afrique le cas de la santé et du secteur agricole en Ouganda / Convergence of economic and social imperatives of policies to fight against poverty in Africa the case of health and agriculture in Uganda

Tankari, Mahamadou Roufahi 27 June 2014 (has links)
Depuis quelques années, investir dans le secteur agricole est devenu un des objectifs prioritaires des politiques économiques de lutte contre la pauvreté en Afrique Subsaharienne. Or, dans la perspective des Objectifs du Millénaire pour le Développement, les pays doivent également faire face à la nécessité croissante d’orienter leurs ressources budgétaires limitées vers le financement de leurs dépenses sociales. Dans ce contexte, en prenant appui sur le cas spécifique de l’Ouganda, l’objectif de cette thèse est de savoir dans quelle mesure il est possible de concilier simultanément ces impératifs sociaux et économiques en exploitant les effets de croissance de certaines dépenses sociales dans la sphère agricole. La santé des ménages agricoles joue alors le rôle de variable stratégique de l’analyse parce qu’elle est à la fois une dimension du bien être dont sont privés les plus pauvres et parce qu’elle détermine également leur niveau de productivité. Dans un premier temps, les facteurs socioéconomiques qui influencent la dépense en santé des Ougandais ont été identifiés. Ils révèlent la complexité de ce processus de dépense, ses relations avec la morbidité et le choix du type de fournisseurs de soins ou les interdépendances entre les différentes catégories de dépenses en soins. Dans un deuxième temps, l’analyse porte une seconde composante essentielle de la santé : la diversité alimentaire. Elle révèle une hétérogénéité inobservée a priori entre les ménages ougandais ainsi que les principaux déterminants socio-économiques de leur demande de diversité alimentaire. Dans un troisième temps, l’accent est mis sur la nature et l’intensité du lien entre les différentes catégories de dépense en santé et la productivité des agriculteurs ougandais. Enfin, une partie de ces résultats micro-économétriques est replacée dans un cadre d’Equilibre Général pour simuler les impacts macroéconomiques et microéconomiques d’une subvention publique du prix des produits de santé non marchands en Ouganda. Les résultats obtenus montrent alors qu’il semble possible de mener dans ce pays des politiques répondant simultanément aux besoins sociaux de court terme de la population et aux impératifs économiques de plus long terme de croissance pro-pauvres, et d’en maximiser les effets à moindre coût en ciblant certains types de ménages et/ou certains types de services de santé. / In recent years, investment in agriculture has become one of the priority objectives of economic policies to fight against poverty in Sub-Saharan Africa. However, from the perspective of Millennium Development Goals, African countries must also deal with the increasing need to focus their scarce budgetary resources towards social spending. In this context, taking the specific case of Uganda, the objective of this thesis is to understand how it is possible to simultaneously achieve these social and economic goals by exploiting the growth effects of some social spending in the agricultural sector. Farmers ‘health plays a critical role of the analysis because it is both a dimension of well-being which are denied to the poor and a determinant of their productivity. At first, socio-economic factors that influence health spending of Ugandans have been identified. They reveal the complexity of this expenditure process, its relationship with morbidity and the choice of healthcare providers, or the interdependencies between the different types of healthcare expenditures. Next, the analysis focuses on a second essential component of health: food diversity. It reveals an a priori unobserved heterogeneity between Ugandan households and the main socio-economic determinants of their demand for food diversity. In a third step, emphasis is placed on the nature and intensity of the link between the different categories of health expenditure and the productivity of Ugandan farmers. Lastly, some of these previous micro-econometric results are replaced in a general equilibrium framework to simulate the macroeconomic and microeconomic impacts of government subsidies on health in Uganda. Results show that it seems possible to design policy in this country which meets simultaneously the short-term social needs of population and the longer-term economic imperatives of pro-poor growth. They also show that it is possible to maximize the effects of these policies at lower cost by targeting certain types of households and / or certain types of health services.
66

Are there alternatives to greenbelts? : evidence from a new land-use transport interaction model for Greater Beijing

Ma, Mingfei January 2017 (has links)
Urban greenbelts are considered a key instrument for shaping sustainable urban growth and protecting the environment in a large number of cities in the world. In most cities, there is a widely shared belief that urban greenbelts are beneficial to the natural environment. By contrast, there is little understanding of the underlying economic impacts of greenbelts and other green space configurations in fast growing cities. The unprecedented rate and scale of urbanisation in the emerging economies has brought the role of greenbelts into an even sharper focus. In cities within these fast growing economies, the urban population is expected to double in the coming decades, which means that greenbelts are under great pressures to adapt to the large forthcoming growth. Few existing urban models are capable of addressing the dynamic nature of the urban transformations and predicting the impacts of urban greenbelts in the developing world. This prompts us to develop a new modelling method that is capable of assessing the impacts of different configurations, scales and locations of green spaces. We then use it to examine alternative futures to the greenbelt through a case study of Greater Beijing. The method we developed is a new variant in the land use-transport interaction (LUTI) model family. This model is capable of addressing the non-equilibrium nature of urban land use and transport development and the equilibrium nature of the day-to-day adaptations made by businesses and citizens. This LUTI model aims to answer the following questions: what are the short-term and long-term economic impacts of a greenbelt on a fast growing city? Which alternative green space configuration performs better in terms of economic well-being and travel costs? Where and how much should the greenbelt land be progressively reshaped or released as the city grows? The new LUTI model is calibrated and validated using data collected for 1990, 2000 and 2010 for Greater Beijing, The model is first tested retrospectively through revisiting the past greenbelt policies in Beijing from 1990 to 2010. Then the impacts of different future green space configurations from 2010 to 2030 are predicted and assessed through quantifying economic costs/benefits and travel costs for socio-economic groups. The model results suggest that under rapid transformative urban change, the configuration, scale and location of a greenbelt have a significant impact on a city’s economic efficiency. Such impacts will transcend the greenbelt boundary, and even the boundary of Beijing Municipality, onto the entire city region. A narrow greenbelt launched in the early age of urban expansion could lead to spatial mismatch of residents and jobs. A wide and strictly controlled ring-shaped greenbelt is not the highest performing intervention either, in terms of economic well-being. The green-wedges configuration is a remedial policy that balances the economic efficiency and environmental benefits. Intensive development around metro/rail stations in the designated greenbelt could reduce spatial costs and promote sustainable travel modes. This implies that a careful siting of new development within existing designations of the greenbelt can be beneficial in terms of economic well-being and sustainable transport.
67

Est-ce que le vieillissement peut être une opportunité pour l’économie française ? / Can ageing be an opportunity for the French economy?

Badji, Ikpidi 13 December 2016 (has links)
Le vieillissement démographique en France constitue un sujet de préoccupation majeure et fait l'objet de plusieurs recherches du point de vue économique. La plupart des études mettent en évidence les effets négatifs du vieillissement sur l'économie française notamment sur les comptes de la protection sociale et le marché du travail. Récemment une nouvelle littérature relative au vieillissement émerge. Celle-ci cherche à savoir et à montrer en quoi le vieillissement peut être une opportunité pour l'économie. Cette thèse s'inscrit dans cette littérature. Elle cherche à répondre à la question suivante : Est-ce que le vieillissement peut être une opportunité pour l'économie française ? Pour répondre à cette question, la thèse explore les pistes de l'épargne et de la consommation en insistant sur la partie de la consommation. La thèse est articulée en cinq chapitres. Le chapitre 1 décrit les causes du vieillissement démographique en France et dresse un état des lieux des études qui portent sur l'effet de ce phénomène sur l'économie française. Le chapitre 2 analyse l'évolution du revenu, du niveau de consommation et du taux d'épargne au cours du cycle de vie et selon les générations afin d'appréhender l'évolution la consommation et du taux d'épargne agrégés dans une société vieillissante et avec le renouvellement des générations. Ces résultats permettent également de comparer le niveau de vie des classes d'âge et des différentes générations. Le chapitre 3 se focalise sur l'évolution de la structure de consommation selon l'âge, les générations et suite à une modification du revenu du ménage. Le chapitre 4 part du constat de la modification de la structure de consommation au cours du temps, la différence de la structure de consommation entre les ménages d'âge actif et les seniors pour estimer les échelles d'équivalence de 1979 à 2010, des seniors et des ménages d'âge actif. Ces échelles permettent de comparer le niveau de vie des seniors et des ménages d'âge actif en tenant compte des économies d'échelles réalisées au sein des différents ménages. Enfin le chapitre 5 utilise un modèle d'équilibre général pour quantifier l'effet du vieillissement sur la structure de consommation, productive et de l'emploi. / The ageing population in France is a subject of major concern and has been the subject of several studies from the economical perspectives. Most of studies highlight the negative effects of aging on the French economy, particularly on social protection accounts, the labor market. Recently a new literature on ageing emerges. It seeks to know and show how ageing can be an opportunity for the economy. This thesis is part of this literature. It seeks to answer the following question: Is Ageing can be an opportunity for the French economy? To answer to this question, the thesis explores the tracks of savings and consumption insisting on the consumption. The thesis is organized in five chapters. Chapter 1 describes the causes of ageing in France and provides an overview of studies covers the effect of this phenomenon on the French economy. Chapter 2 analyzes the evolution of income, consumption levels, and savings rates over the life cycle and according to the generations, to understand the evolution of aggregate consumption and aggregate savings rate in a society that's facing ageing and the renewal generations. These results also allow us to compare standards of living of age groups and different generations. Chapter 3 focuses on the evolution of consumption structure by age, generations. It provides also information about evolution of consumption structure when the household income changes. Chapter 4 began from the observation of the change in structure consumption over time, the difference in consumption structure between working-age households and seniors to estimate equivalence scales from 1979 to 2010, seniors and working-age households. These scales are used to compare the standards of living of seniors and working-age households, taking into account economies of scale achieved within different households. Finally Chapter 5 uses a general equilibrium model to quantify the effect of aging on the structure of consumption, productive and employment.
68

Modélisation de la cavitation par une approche à interface diffuse avec prise en compte de la tension de surface / A Diffuse Interface model for cavitation taking into account surface tension force

Ait-Ali, Takfarines 29 September 2015 (has links)
La cavitation est la transformation d'un liquide en vapeur qui est causée par une chute de pression en dessous de la pression de saturation vapeur. Ce phénomène se manifeste le plus souvent dans les turbomachines qui sont en interaction avec des liquides. On peut citer les pompes hydrauliques, les injecteurs, les inducteurs ou encore les hélices de bateaux. Vue les effets néfastes qu'elle engendre : bruit, vibrations, détérioration du métal et baisse des performances (chute des rendements et pertes de charges), sa prise en compte est indispensable dans le design des turbomachines. Cette thèse a pour objectif de modéliser ce phénomène de manière à reproduire la nucléation, la convection et l'implosion des bulles de cavitation. Nous nous basons sur un modèle à interface diffuse (le modèle d'équilibre homogène) sur lequel nous greffons un modèle de tension de surface basé sur les équations de Navier Stokes & Korteweg compressibles. Nous réalisons en somme une étude sur l'influence de la tension de surface sur le phénomène de collapse. Nous utilisons un code de volumes finis dont la discrétisation spatiale est assurée par méthode des moindres carrés mobiles. Combinée à un solveur de Riemann de type SLAU, le modèle numérique permet d'outre passer les difficultés liés à la nature du phénomène de cavitation qui sont principalement les forts gradients qui subsistent à travers l'interface liquide-vapeur. L'autre point traité dans la thèse est la détermination d'un coefficient capillaire numérique qui correspond à une tension de surface réelle en fonction de l'épaisseur de l'interface artificiellement élargie pour un maillage donné. / Cavitation is the transformation of a liquid into vapor which is caused by a pressure drop below the vapor saturation pressure. This phenomenon usually occurs in turbine engines that interact with liquids like: hydraulic pumps, injectors, inductors or boat propellers. View its negative effects: noise, vibrations, damage to the metal and decreased performance, it should be included in the design of turbomachinery The main objective of this thesis is to model this phenomenon so as to reproduce the nucleation, convection and the implosion of cavitation bubbles. We rely on a diffuse interface model (the homogeneous equilibrium model) on which we graft a surface tension model based on compressible Navier Stokes & Korteweg equations. We study the influence of surface tension on the bubble collapse. We used a finite volume approach whose spatial discretization is made by moving least squared method. Coupled with a Riemann solver called SLAU, the numerical model can go further difficulties related to the nature of the cavitation phenomenon which is mainly the strong gradients that remain through the liquid-vapor interface. Another issue addressed in this thesis is the determination of a numerical capillary coefficient which corresponds to a real surface tension in function of the thickness of the artificially extended interface for a given mesh.
69

Exposition aux composés organiques semi-volatils reprotoxiques et neurotoxiques dans l'habitat / Exposure to semi-volatile organic compounds in French dwellings

Blanchard, Olivier 18 December 2014 (has links)
Les composés organiques semi-volatils (COSVs) regroupent un grand nombre de composés chimiques utilisés notamment comme substances actives ou additifs dans les matériaux de construction, de décoration et dans de nombreux produits de consommation. Les COSVs sont omniprésents dans les environnements intérieurs et fréquemment détectés dans les poussières sédimentées et dans le compartiment aérien. Cette thèse a permis de documenter les concentrations de 57 composés dans 30 logements français et d'utiliser ces mesures pour tester un modèle d'équilibre visant à prédire leur répartition dans les différents compartiments de l'environnement intérieur. De ce travail, il ressort une forte ubiquité des COSVs dans les logements étudiés. Les concentrations les plus élevées ont été observées pour les phtalates et dans une moindre mesure pour le bisphénol A, les muscs synthétiques et certains pesticides et HAPs. Ces résultats confirment l'intérêt de mieux caractériser l'exposition de la population générale aux COSVs dans l'habitat français. Les travaux portant sur le modèle d'équilibre ont montré que le coefficient de partage entre l'air et l'octanol (Koa) peut être un bon prédicteur pour estimer la concentration d'un composé donné dans un ensemble de logements. Cependant, certaines limites ont été identifiées et une meilleure caractérisation des paramètres utilisés est recommandée. / Semivolatile organic compounds (SVOCs) include a large number of chemicals compounds used as active substances or additives in building materials and in many consumer products. SVOCs are ubiquitous in indoor environments and frequently detected in settled dust and indoor air. This work has investigated indoor concentrations of 57 target compounds in 30 French dwellings and measurements were used to test an equilibrium model to predict their partitioning in indoor compartments. The results showed a strong ubiquity of SVOCs in French dwellings. The highest concentrations were measured for phthalates and to a lesser extent for bisphenol A, synthetic musks, some pesticides and PAHs. These results confirm the interest to assess human exposure to SVOCs in the French dwellings. The work on the predictive model showed that octanol/air partitioning coefficient (Koa) is a good predictor to estimate SVOC concentrations in a large number of buildings. However, some limits were identified and a better estimation of the parameters used in these models is required.
70

[en] NUMERICAL SIMULATION OF TWO-PHASE GAS PIPELINE BLOWDOWN WITH HOMOGENEOUS MODEL / [pt] SIMULAÇÃO NUMÉRICA DE ESCOAMENTOS BIFÁSICOS EM EVENTOS DE DESPRESSURIZAÇÃO DE GASODUTOS UTILIZANDO O MODELO HOMOGÊNEO

FERNANDO MARTINS CAMPOS COELHO 12 August 2016 (has links)
[pt] O Brasil possui uma já extensa malha offshore de gasodutos e, no desenvolvimento da produção do Pré-Sal, esta deve continuar se expandindo em razão das necessidades de aumento da capacidade de escoamento de gás e também da sua reinjeção nos próprios reservatórios (seja apenas como descarte ou como um método de recuperação avançado). Uma vez instalada, esta malha deve ser periodicamente passar por manutenção, o que implica em eventos esporádicos de esvaziamento destes dutos, normalmente operando a altas pressões. Devido ao custo elevado de tais operações, deve-se estimar com boa precisão o tempo total necessário para despressurização, que pode levar várias horas ou até dias. Além disso, também é importante a previsão do inventário de líquido remanescente nos dutos após a despressurização. No presente trabalho, foi desenvolvido um modelo numérico para prever a despressurização de gasodutos considerando escoamento bifásico homogêneo e unidimensional. A formação e o consumo de condensado é obtida a partir de um inventário inicial de fluido supercrítico, com premissa de equilíbrio entre as fases. As propriedades termodinâmicas dos fluidos são determinadas utilizando-se pacotes comerciais e pré-tabuladas em função de pressão e temperatura. As equações de conservação foram discretizadas pelo método das diferenças finitas, utilizando o método de Euler implícito para o termo temporal e aproximação upwind nas derivadas espaciais. O sistema algébrico resultante foi resolvido diretamente de forma acoplada. Os resultados obtidos mostram boa concordância ao compará-los a dados reais de campo e resultados de simuladores comerciais de referência. / [en] Although Brazilian gas pipeline grid is already quite extensive, it continues to expand due to the Pre Salt development, since there is a growing need to increase the flowing capacity towards onshore facilities and injection wells (gas to be discarded or used for advanced oil recovery). Once pipelines are installed, maintenance operation must be performed quite often to guarantee process efficiency. Usually these operations demand depressurization from very high pressures. Considering the costs involved in such operations it is mandatory to accurately predict the total time for a complete blowdown, which may take several hours or even a couple of days. Furthermore, it is also important to evaluate the condensate content in the pipeline after the depressurization event. In the present work, a numerical model was developed to simulate gas pipeline depressurization considering unidimensional two-phase homogeneous flow. The formation and consumption of condensate from an initial supercritical state is obtained assuming phase equilibrium. Fluid properties are taken from tables generated by PVT packages. Conservation equations are discretized through the finite difference method employing Euler implicit approximation for the time derivatives and upwind scheme for spatial terms. A coupled direct algorithm was adopted to solve the resulting algebraic system. The results are compared to real field data and commercial software showing good agreement.

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