971 resultados para Adsorção Métodos de simulação
Resumo:
A avaliao da solicitao produzida por exploses, assim como da resposta de estruturas, so temas de muito interesse na engenharia atualmente, tanto pela quantidade crescente de acidentes relacionados com exploses quanto pelas aes terroristas muitas vezes vinculadas a estes tipos de aes. Neste contexto, o presente trabalho tem por objetivo explorar tcnicas de anlise tanto na modelagem da excitao quanto na resposta de estruturas consideradas como alvos. Para isto, so utilizadas metodologias de diferentes tipos: implementaes baseadas em sistema de elementos finitos comerciais como Ansys [2000] e LS-Dyna [2003] e tcnicas simplificativas que permitem realizar uma avaliao preliminar. As aplicaes consideradas so indicadas a seguir: Anlise da Resposta de Estruturas Laminares Submetidas Ao de Cargas Explosivas: determina-se a presso produzida por explosivos slidos a certa distncia do epicentro, atravs de métodos simplificados, determinando a resposta esperada em placas retangulares; Efeito da Presso Interna em Vasos de Presso (Extintores de Incndio): comparando resultados numricos e experimentais verifica-se a influncia da presso interna nas propriedades dinmicas do sistema; Estudo de Um Vaso Esfrico de GLP Sob Ao de Uma Carga Explosiva: aplica-se a ao de uma onda explosiva produzida por um gs inflamvel pesado sobre uma estrutura de vaso de presso esfrico com fluido e gs em seu interior, determinando sua resposta, avaliando tambm a influncia de diferentes quantidades de lquido e presso interna na resposta da estrutura; Modelamento de uma Camada de Solo / Propagao das Ondas: verifica-se o comportamento da propagao de ondas em um meio elstico, comparando valores encontrados em testes experimentais. Analisa-se numericamente o efeito da insero de uma valeta na atenuao de tais ondas; Simulação Numrica Completa de uma Exploso: modela-se um semi-espao submetido ao de um explosivo slido sobre sua superfcie, avaliando os campos de presso gerados. Ao final de cada aplicao so apresentadas concluses parciais obtidas e as possibilidades de trabalhos futuros vislumbrados. Finalmente, conclui-se que as tcnicas empregadas para as simulaes so extremamente eficientes, considerando conhecidos todos os parmetros envolvidos em cada modelo. Neste ponto fundamental o trabalho do engenheiro, utilizando-se de seus conhecimentos tcnicos para transformao do evento real em um modelo numrico, considerando e selecionando as simplificaes necessrias.
Resumo:
Outliers so observaes que parecem ser inconsistentes com as demais. Tambm chamadas de valores atpicos, extremos ou aberrantes, estas inconsistncias podem ser causadas por mudanas de poltica ou crises econmicas, ondas inesperadas de frio ou calor, erros de medida ou digitao, entre outras. Outliers no so necessariamente valores incorretos, mas, quando provenientes de erros de medida ou digitao, podem distorcer os resultados de uma anlise e levar o pesquisador concluses equivocadas. O objetivo deste trabalho estudar e comparar diferentes métodos para deteco de anormalidades em sries de preos do ndice de Preos ao Consumidor (IPC), calculado pelo Instituto Brasileiro de Economia (IBRE) da Fundao Getulio Vargas (FGV). O IPC mede a variao dos preos de um conjunto xo de bens e servios componentes de despesas habituais das famlias com nvel de renda situado entre 1 e 33 salrios mnimos mensais e usado principalmente como um ndice de referncia para avaliao do poder de compra do consumidor. Alm do mtodo utilizado atualmente no IBRE pelos analistas de preos, os métodos considerados neste estudo so: variaes do Mtodo do IBRE, Mtodo do Boxplot, Mtodo do Boxplot SIQR, Mtodo do Boxplot Ajustado, Mtodo de Cercas Resistentes, Mtodo do Quartil, do Quartil Modicado, Mtodo do Desvio Mediano Absoluto e Algoritmo de Tukey. Tais métodos foram aplicados em dados pertencentes aos municpios Rio de Janeiro e So Paulo. Para que se possa analisar o desempenho de cada mtodo, necessrio conhecer os verdadeiros valores extremos antecipadamente. Portanto, neste trabalho, tal anlise foi feita assumindo que os preos descartados ou alterados pelos analistas no processo de crtica so os verdadeiros outliers. O Mtodo do IBRE bastante correlacionado com os preos alterados ou descartados pelos analistas. Sendo assim, a suposio de que os preos alterados ou descartados pelos analistas so os verdadeiros valores extremos pode inuenciar os resultados, fazendo com que o mesmo seja favorecido em comparao com os demais métodos. No entanto, desta forma, possvel computar duas medidas atravs das quais os métodos so avaliados. A primeira a porcentagem de acerto do mtodo, que informa a proporo de verdadeiros outliers detectados. A segunda o nmero de falsos positivos produzidos pelo mtodo, que informa quantos valores precisaram ser sinalizados para um verdadeiro outlier ser detectado. Quanto maior for a proporo de acerto gerada pelo mtodo e menor for a quantidade de falsos positivos produzidos pelo mesmo, melhor o desempenho do mtodo. Sendo assim, foi possvel construir um ranking referente ao desempenho dos métodos, identicando o melhor dentre os analisados. Para o municpio do Rio de Janeiro, algumas das variaes do Mtodo do IBRE apresentaram desempenhos iguais ou superiores ao do mtodo original. J para o municpio de So Paulo, o Mtodo do IBRE apresentou o melhor desempenho. Em trabalhos futuros, espera-se testar os métodos em dados obtidos por simulação ou que constituam bases largamente utilizadas na literatura, de forma que a suposio de que os preos descartados ou alterados pelos analistas no processo de crtica so os verdadeiros outliers no interra nos resultados.
Resumo:
Os escoamentos no interior de zonas urbanas, apresentam grande heterogeneidade, pelo que a sua caracterizao, requer uma formulao que incorpore explicitamente essa variabilidade espacial. A caracterizao, simulação ( escala) e modelao do escoamento em canais artificiais e a aplicao a um caso de estudo, no Laboratrio de Hidrulica da UMa, representa o cerne desta dissertao. Os objetivos principais desta dissertao so: a caracterizao e desenvolvimento de ferramentas de simulação do comportamento do escoamento em canais artificiais, no caso de uma variao sbita dos caudais afluentes, mecanismos de preveno de cheia; o desenvolvimento de um modelo de simulação hidrodinmico, considerando os escoamentos variveis em superfcie livre no caso de situaes de cheia, na simulação entre as condies variveis das afluncias, das condies hidromorfolgicas do canal e da instalao e operao dos sistemas e regulao dos escoamentos; e ainda a anlise da viabilidade da simulação (modelo) na gesto e preveno de cheias em canais artificiais. Numa primeira instncia, procede-se recolha de toda a informao bibliogrfica disponvel. Com recurso aos modelos digitais do terreno e ao programa ArcGis, efetuada toda uma exaustiva caracterizao da bacia hidrogrfica, relativa ao caso de estudo (canal artificial), a partir da qual foi possvel obter os dados inerentes s caractersticas geomtricas, caractersticas de relevo e caractersticas de drenagem. Segue-se a anlise da precipitao com recurso a folhas de clculo e dados fornecidos pelas instituies pertinentes, de forma a obter valores de precipitao mdia diria e anual para aplicao de frmulas, tanto para calcular valores de tempo de concentrao, bem como caudais. O prximo passo selecionar os troos relevantes do canal em estudo e com recurso ao equipamento disponvel no Laboratrio de Hidrulica da UMa, folha de clculo programada e ao programa HEC-RAS procede-se simulação/modelao/anlise desses troos, comparando o resultado/comportamento simulado, com o expectvel e entre os vrios métodos. Por fim, so expostas as concluses, bem como algumas consideraes finais e uma listagem de objetivos a manter ou alcanar nos prximos anos, onde se incluem, aes prioritrias e recomendaes visando, no s melhorar o processo de caracterizao do escoamento em canais artificiais, bem como simplificar a preveno e gesto de cheias.
Resumo:
Natural ventilation is an efficient bioclimatic strategy, one that provides thermal comfort, healthful and cooling to the edification. However, the disregard for quality environment, the uncertainties involved in the phenomenon and the popularization of artificial climate systems are held as an excuse for those who neglect the benefits of passive cooling. The unfamiliarity with the concept may be lessened if ventilation is observed in every step of the project, especially in the initial phase in which decisions bear a great impact in the construction process. The tools available in order to quantify the impact of projected decisions consist basically of the renovation rate calculations or computer simulations of fluids, commonly dubbed CFD, which stands for Computational Fluid Dynamics , both somewhat apart from the project s execution and unable to adapt for use in parametric studies. Thus, we chose to verify, through computer simulation, the representativeness of the results with a method of simplified air reconditioning rate calculation, as well as making it more compatible with the questions relevant to the first phases of the project s process. The case object consists of a model resulting from the recommendations of the Cdigo de Obras de Natal/ RN, customized according to the NBR 15220. The study has shown the complexity in aggregating a CFD tool to the process and the need for a method capable of generating data at the compatible rate to the flow of ideas and are discarded during the project s development. At the end of our study, we discuss the necessary concessions for the realization of simulations, the applicability and the limitations of both the tools used and the method adopted, as well as the representativeness of the results obtained
Resumo:
The assessment of building thermal performance is often carried out using HVAC energy consumption data, when available, or thermal comfort variables measurements, for free-running buildings. Both types of data can be determined by monitoring or computer simulation. The assessment based on thermal comfort variables is the most complex because it depends on the determination of the thermal comfort zone. For these reasons, this master thesis explores methods of building thermal performance assessment using variables of thermal comfort simulated by DesignBuilder software. The main objective is to contribute to the development of methods to support architectural decisions during the design process, and energy and sustainable rating systems. The research method consists on selecting thermal comfort methods, modeling them in electronic sheets with output charts developed to optimize the analyses, which are used to assess the simulation results of low cost house configurations. The house models consist in a base case, which are already built, and changes in thermal transmittance, absorptance, and shading. The simulation results are assessed using each thermal comfort method, to identify the sensitivity of them. The final results show the limitations of the methods, the importance of a method that considers thermal radiance and wind speed, and the contribution of the chart proposed
Resumo:
In Brazil and around the world, oil companies are looking for, and expected development of new technologies and processes that can increase the oil recovery factor in mature reservoirs, in a simple and inexpensive way. So, the latest research has developed a new process called Gas Assisted Gravity Drainage (GAGD) which was classified as a gas injection IOR. The process, which is undergoing pilot testing in the field, is being extensively studied through physical scale models and core-floods laboratory, due to high oil recoveries in relation to other gas injection IOR. This process consists of injecting gas at the top of a reservoir through horizontal or vertical injector wells and displacing the oil, taking advantage of natural gravity segregation of fluids, to a horizontal producer well placed at the bottom of the reservoir. To study this process it was modeled a homogeneous reservoir and a model of multi-component fluid with characteristics similar to light oil Brazilian fields through a compositional simulator, to optimize the operational parameters. The model of the process was simulated in GEM (CMG, 2009.10). The operational parameters studied were the gas injection rate, the type of gas injection, the location of the injector and production well. We also studied the presence of water drive in the process. The results showed that the maximum vertical spacing between the two wells, caused the maximum recovery of oil in GAGD. Also, it was found that the largest flow injection, it obtained the largest recovery factors. This parameter controls the speed of the front of the gas injected and determined if the gravitational force dominates or not the process in the recovery of oil. Natural gas had better performance than CO2 and that the presence of aquifer in the reservoir was less influential in the process. In economic analysis found that by injecting natural gas is obtained more economically beneficial than CO2
Resumo:
Currently, the oil industry is the biggest cause of environmental pollution. The objective was to reduce the concentration of copper and chromium in the water produced by the oil industry. It was used as adsorbent natural sisal fiber Agave sp treated with nitric acid and sodium hydroxide. All vegetable fibers have physical and morphological properties that enablies the adsorption of pollutants. The basic composition of sisal is cellulose, hemicellulose and lignin. The features are typically found in the characterization of vegetable fibers, except the surface area that was practically zero. In the first stage of adsorption, it was evaluated the effect of temperature and time skeeking to optimize the execution of the factorial design. The results showed that the most feasible fiber was the one treated with acid in five hours (30C). The second phase was a factorial design, using acid and five hours, this time was it determined in the first phase. The tests were conducted following the experimental design and the results were analyzed by statistical methods in order to optimize the main parameters that influence the process: pH, concentration (mol / L) and fiber mass/ metal solution volume. The volume / mass ratio factor showed significant interference in the adsorption process of chromium and copper. The results obtained after optimization showed that the highest percentages of extraction (98%) were obtained on the following operating conditions: pH: 5-6, Concentration: 100 ppm and mass/ volume: 1 gram of fiber/50mL solution. The results showed that the adsorption process was efficient to remove chromium and copper using sisal fibers, however, requiring further studies to optimize the process.
Resumo:
Oil production and exploration techniques have evolved in the last decades in order to increase fluid flows and optimize how the required equipment are used. The base functioning of Electric Submersible Pumping (ESP) lift method is the use of an electric downhole motor to move a centrifugal pump and transport the fluids to the surface. The Electric Submersible Pumping is an option that has been gaining ground among the methods of Artificial Lift due to the ability to handle a large flow of liquid in onshore and offshore environments. The performance of a well equipped with ESP systems is intrinsically related to the centrifugal pump operation. It is the pump that has the function to turn the motor power into Head. In this present work, a computer model to analyze the three-dimensional flow in a centrifugal pump used in Electric Submersible Pumping has been developed. Through the commercial program, ANSYS CFX, initially using water as fluid flow, the geometry and simulation parameters have been defined in order to obtain an approximation of what occurs inside the channels of the impeller and diffuser pump in terms of flow. Three different geometry conditions were initially tested to determine which is most suitable to solving the problem. After choosing the most appropriate geometry, three mesh conditions were analyzed and the obtained values were compared to the experimental characteristic curve of Head provided by the manufacturer. The results have approached the experimental curve, the simulation time and the model convergence were satisfactory if it is considered that the studied problem involves numerical analysis. After the tests with water, oil was used in the simulations. The results were compared to a methodology used in the petroleum industry to correct viscosity. In general, for models with water and oil, the results with single-phase fluids were coherent with the experimental curves and, through three-dimensional computer models, they are a preliminary evaluation for the analysis of the two-phase flow inside the channels of centrifugal pump used in ESP systems
Resumo:
The Electrical Submersible Pump (ESP) has been one of the most appropriate solutions for lifting method in onshore and offshore applications. The typical features for this application are adverse temperature, viscosity fluids and gas environments. The difficulties in equipments maintenance and setup contributing to increasing costs of oil production in deep water, therefore, the optimization through automation can be a excellent approach for decrease costs and failures in subsurface equipment. This work describe a computer simulation related with the artificial lifting method ESP. This tool support the dynamic behavior of ESP approach, considering the source and electric energy transmission model for the motor, the electric motor model (including the thermal calculation), flow tubbing simulation, centrifugal pump behavior simulation with liquid nature effects and reservoir requirements. In addition, there are tri-dimensional animation for each ESP subsytem (transformer, motor, pump, seal, gas separator, command unit). This computer simulation propose a improvement for monitoring oil wells for maximization of well production. Currenty, the proprietaries simulators are based on specific equipments manufactures. Therefore, it is not possible simulation equipments of another manufactures. In the propose approach there are support for diverse kinds of manufactures equipments
Resumo:
The investigation of viability to use containers for Natural Gas Vehicle (NGV) storage, with different geometries of commercial standards, come from necessity to join the ambient, financial and technological benefits offered by the gas combustion, to the convenience of not modify the original proposal of the automobile. The use of these current cylindrical models for storage in the converted vehicles is justified by the excellent behavior that this geometry presents about the imposed tensions for the high pressure that the related reservoirs are submitted. However, recent research directed toward application of adsorbent materials in the natural gas reservoirs had proven a substantial redusction of pressure and, consequently, a relief of the tensions in the reservoirs. However, this study considers alternative geometries for NGV reservoirs, searching the minimization of dimensions and weight, remaining capacity to resist the tensions imposed by the new pressure situation. The proposed reservoirs parameters are calculated through a mathematical study of the internal pressure according to Brazilian standards (NBR) for pressure vessels. Finally simulations of the new geometries behavior are carried through using a commercially avaible Finite Element Method (FEM) software package ALGOR to verify of the reservoirs efficincy under the gas pressure load
Resumo:
Currently there is still a high demand for quality control in manufacturing processes of mechanical parts. This keeps alive the need for the inspection activity of final products ranging from dimensional analysis to chemical composition of products. Usually this task may be done through various nondestructive and destructive methods that ensure the integrity of the parts. The result generated by these modern inspection tools ends up not being able to geometrically define the real damage and, therefore, cannot be properly displayed on a computing environment screen. Virtual 3D visualization may help identify damage that would hardly be detected by any other methods. One may find some commercial softwares that seek to address the stages of a design and simulation of mechanical parts in order to predict possible damages trying to diminish potential undesirable events. However, the challenge of developing softwares capable of integrating the various design activities, product inspection, results of non-destructive testing as well as the simulation of damage still needs the attention of researchers. This was the motivation to conduct a methodological study for implementation of a versatile CAD/CAE computer kernel capable of helping programmers in developing softwares applied to the activities of design and simulation of mechanics parts under stress. In this research it is presented interesting results obtained from the use of the developed kernel showing that it was successfully applied to case studies of design including parts presenting specific geometries, namely: mechanical prostheses, heat exchangers and piping of oil and gas. Finally, the conclusions regarding the experience of merging CAD and CAE theories to develop the kernel, so as to result in a tool adaptable to various applications of the metalworking industry are presented
Resumo:
The progressing cavity pumping (PCP) is one of the most applied oil lift methods nowadays in oil extraction due to its ability to pump heavy and high gas fraction flows. The computational modeling of PCPs appears as a tool to help experiments with the pump and therefore, obtain precisely the pump operational variables, contributing to pump s project and field operation otimization in the respectively situation. A computational model for multiphase flow inside a metallic stator PCP which consider the relative motion between rotor and stator was developed in the present work. In such model, the gas-liquid bubbly flow pattern was considered, which is a very common situation in practice. The Eulerian-Eulerian approach, considering the homogeneous and inhomogeneous models, was employed and gas was treated taking into account an ideal gas state. The effects of the different gas volume fractions in pump volumetric eficiency, pressure distribution, power, slippage flow rate and volumetric flow rate were analyzed. The results shown that the developed model is capable of reproducing pump dynamic behaviour under the multiphase flow conditions early performed in experimental works
Resumo:
In this work it was synthesized and characterized the cobalt ferrite (CoFe2O4) by two methods: complexation combining EDTA/Citrate and hydrothermal investigating the influence of the synthesis conditions on phase formation and on the crystallite size. The powders were mainly characterized by x-ray diffraction. In specific cases, it was also used scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray fluorescence (XRF) and isotherms of adsorption and desorption of nitrogen (BET method). The study of the crystallite size was based on the interpretation of x-ray diffractograms obtained and estimated by the method of Halder-Wagner-Scherrer and Langford. An experimental design was made in order to assist in quantifying the influence of synthesis conditions on the response variables. The synthesis parameters evaluated in this study were: pH of the reaction medium (8, 9 and 10), the calcination temperature (combined complexation method EDTA/Citrate 600C, 800C and 1000C), synthesis temperature (hydrothermal method 120C, 140C and 160C), calcination time (combined complexation method EDTA/Citrate - 2, 4 and 6 hours) and time of synthesis (hydrothermal method 6, 15 and 24 hours). By the hydrothermal method was possible to produce mesoporous powders with high purity, with an average crystallite size up to 7 nm, with a surface area of 113.44 m/g in the form of pellets with irregular morphology. By using the method of combined complexation EDTA/Citrate, mesoporous powders were produced with greater purity, crystallite size up to 22nm and 27.95 m/g of surface area in the form of pellets with a regular morphology of plaques. In the experimental design was found that the hydrothermal method to all the studied parameters (pH, temperature and time) have significant effect on the crystallite size, while to the combined complexation method EDTA/Citrate, only temperature and time were significant
Resumo:
In this thesis we study some problems related to petroleum reservoirs using methods and concepts of Statistical Physics. The thesis could be divided percolation problem in random multifractal support motivated by its potential application in modelling oil reservoirs. We develped an heterogeneous and anisotropic grid that followin two parts. The first one introduce a study of the percolations a random multifractal distribution of its sites. After, we determine the percolation threshold for this grid, the fractal dimension of the percolating cluster and the critical exponents and v. In the second part, we propose an alternative systematic of modelling and simulating oil reservoirs. We introduce a statistical model based in a stochastic formulation do Darcy Law. In this model, the distribution of permeabilities is localy equivalent to the basic model of bond percolation
Resumo:
Conselho Nacional de Desenvolvimento Cientfico e Tecnolgico
