Seminários e Teses

Próximos- Anteriores-
Próxima semana (de 23/01 a 29/01)
Tese de Doutorado
25/01
Interfacial rheology and properties of island-type asphaltenes
Isabela Fernandes Soares, PUC-Rio

Data: 25/01/2022 às 15h e 0min
Local: por acesso remoto


Orientador: Mônica Naccache
Área de Concentração: Termociências

Resumo

Adsorption of asphaltene molecules at the oil-water interface induces the formation of a complex microstructure, which stabilizes emulsions and impairs the efficiency of crude oil refining. In this work, we design a set of new shear rheology protocols to assess the effect of polar and non-polar solvents on indigenous Brazilian (BR) asphaltene adsorption. Moreover, the asphaltene morphology upon addition of solvents with distinct aromaticities is investigated by SEM microscopy. Our findings indicate that asphaltenes are a polycondensate aromatic island-type structure that forms reversible films when polar solvents are placed on top of the adsorbed film. The interfacial study also reveals that non-polar solvents induce precipitation/adsorption of asphaltenes at the oil-water interface. The asphaltene aggregates, upon the presence of weakly polar solvents, can consolidate into a more close-packed pattern, suggesting that network growth and asphaltene self-arrangement are directly related to the aromatic content. We explore the differences in asphaltene structuring and how it affects the extent of spontaneous emulsification. We find that the rate of emulsification is directly related to the chemical configuration of asphaltenes. Finally, we study the addition of stearic acid (SA) to asphaltene solutions in deionized water (DW) and synthetic water (SW) to better understand how surface and rheological properties are affected by competitive adsorption. We find that single SA are more prone to form liquid-like rather than solid-like films at the air-water interface. Furthermore, we show that the interfacial activity of our asphaltenes is enhanced in the presence of electrolytes and is dependent of the solvent aromaticity.

Link da defesa:

https://puc-rio.zoom.us/j/91264826112?pwd=UFdqQk0wQXBwcGNHUFNJbGZlVEdZZz09

Meeting ID: 912 6482 6112

Passcode: 175095


Dissertação de Mestrado
26/01
Reservoir characterization based on pressure and temperature transient data, using an ensemble-based method
Vinicius Mattoso Reis da Silva, PUC-Rio

Data: 26/01/2022 às 13h e 30min
Local: por acesso remoto


Orientador: Márcio Carvalho
Área de Concentração: Petróleo e Energia

Resumo

Reservoir characterization is an important tool for production/reservoir management. Well tests are commonly used in reservoir characterization and are the only source of dynamic data during the exploitation period. These tests typically measure the pressure and temperature responses at a well during controlled production, injection, or static conditions. Generally, only pressure data is post-processed in reservoir characterization. However, considering only pressure data can lead to misinterpretation associated with the neglected thermal effects, causing errors in reservoir properties estimation and consequently inefficient reservoir management. Besides that, pressure data have several noise sources that may compromise the accuracy of test results. Recent results have shown that temperature data can be used to improve reservoir parameter estimation. In this work, the ensemble smoother with multiple data assimilation method (ES-MDA) was applied in synthetic cases created by an in-house non-isothermal reservoir-well flow simulator that considers the Joule-Thomson heating and cooling, adiabatic fluid expansion/compression, conduction, and convection effects in the thermal energy balance equation. The synthetic measured data was obtained by adding gaussian and harmonics noises to the numerical predictions to simulate equipment and tidal effects, respectively. A sensitivity analysis of the effect of the CD matrix used for updating parameters of the ES-MDA method on the parameters estimations was carried out. The results show that adding temperature data to the observed data in the history matching improves the estimates of the reservoir parameters, especially for the skin region and reservoir porosity. For the analyses in which the pressure data had the addition of harmonic noise, the inclusion of temperature data also proved to be of great importance for an accurate characterization of the reservoir.

Link da defesa:

https://puc-rio.zoom.us/j/94290757371?pwd=UHh6WVB0dzUvL0pmM0RjT0xPQTU5dz09

Meeting ID: 942 9075 7371
Passcode: 000906
 


Semana de 30/01 a 05/02
Tese de Doutorado
31/01
Coupling Machine Learning and Mesoscale Modeling to Study the flow of semi-dense and dense suspensions
Erika Imada Barcelos, PUC-Rio

Data: 31/01/2022 às 16h e 0min
Local: por acesso remoto


Orientador: Monica Naccache e João Maia
Área de Concentração: Termociências

Resumo

Suspensions correspond to a class of materials vastly used in a large set of applications and industries. Due to its extreme versatility, they have been the focus of numerous studies over the past decades. Suspensions are also very flexible and can display different rheological properties and macroscopic responses depending on the choice of parameters used as input in the system. More specifically, the rheological response of suspensions is intimately associated to the microstructural arrangement of the particles composing the medium and external factors, such as how strongly they are confined and particle rigidity. In the present study, the effect of particle rigidity, confinement, and flow rate on the microstructure of highly concentrated suspensions is studied using Core-Modified Dissipative Particle Dynamics. Preceding this main study, two other steps were necessary to guarantee a reliable and realistic simulation system, which consisted, essentially, on performing parametric studies to understand and estimate the appropriate values for wall-particle interaction parameters.
Chapter 2 and Chapter 3 of the present work address parametric studies performed to assist the input parameters choice to prevent particle penetration in a wall-bounded system. In Chapter 2 a simpler system, composed of solvent and walls, is built and the interaction parameters and wall densities are adjusted. In Chapter 3 the interactions are set for suspensions. In the latter case multiple parameters play a role in penetration and the traditional way to investigate these effects would be exhaustive and time consuming. Hence, we choose to use a Machine Learning approach to perform this study. Once the parameters were adjusted, the study of confinement could be carried out, in Chapter 4. The main goal of this Chapter was to understand how the microstructure of concentrated suspensions is affected by flow rate, particle rigidity and confinement. It was found that very soft particles always form a giant cluster regardless the confinement ratio; the difference being on how packed the particles are. In the rigid case, a stronger confinement leads the formation of larger clusters. Chapter 5 addresses a machine learning study carried out to predict the rheology of unconfined suspensions. The main contribution of this work is that it was possible to understand and adjust simulation parameters that affect unrealistic the physics of the system and develop a computational domain that enables to systematically study confinement effects on suspensions.

Link da defesa:

https://cwru.zoom.us/j/98796685273?pwd=ajBPa3N3dS9KOHdBOWJoeXlWRlVZQT09

 


Dissertação de Mestrado
02/02
Desenvolvimento de um Modelo Numérico para Análise Energética e Exergética de Caldeiras Flamo-Tubulares Operando em Regime Permanente com Gás Natural
Vanessa Bautista Paganelli, PUC-Rio

Data: 02/02/2022 às 15h e 0min
Local: por acesso remoto


Orientador: José A. Parise e Florian Pradelle
Área de Concentração: Termociências

Resumo

Desde os primórdios da Revolução Industrial, caldeiras têm percorrido um longo caminho de desenvolvimento visando melhor segurança e maior eficiência. Em particular, o mercado de caldeiras flamotubulares tem exigido cada vez mais projetos personalizados dos fabricantes, abrindo caminho para o uso de modelos de caldeiras como eficientes ferramentas de projeto. Neste trabalho, foi desenvolvido um modelo termodinâmico para uma caldeira flamotubular, de três passes, operando em regime permanente com gás natural boliviano. Foi testada a sensibilidade no perfil de temperatura de várias correlações de troca de calor encontradas na literatura. Um planejamento composto central permitiu avaliar simultaneamente o impacto da variação de seis parâmetros (diâmetro dos tubos no primeiro, segundo e terceiro passes, comprimento da caldeira, número de tubos nos passes 2 e 3 e porcentagem de excesso de ar na combustão) e obter um modelo polinomial empírico a fim de otimizar as eficiências energética e exergética de caldeira. Um teste de malha foi realizado com temperaturas no final da chama, câmara de combustão, segundo e terceiro passes e apontou para uma divisão suficiente de 200 volumes de controle em cada passe. O modelo foi também validado com dados obtidos experimentalmente, observando-se que a diferença entre os valores experimentais e teóricos das temperaturas do primeiro e segundo passes é inferior a 22,9ºC e menor que 43,9ºC no terceiro passe. Com os modelos polinomiais robustos obtidos com o planejamento de experimentos, foi possível observar os parâmetros mais significativos, tanto para as eficiências energética e exergética, assim como para a destruição de exergia. São eles, por ordem decrescente de importância: o excesso de ar; as duas contribuições associadas ao comprimento da caldeira; o número de tubos nos segundo e terceiro passes e; o diâmetro dos tubos no segundo e terceiro passe e o diâmetro do tubo no primeiro passe. Além disso, foi possível quantificar o trade-off entre o aumento da superfície de troca de calor e a manutenção do nível de turbulência do escoamento.

Link da defesa:

https://puc-rio.zoom.us/j/93257958274?pwd=UmN3dnRFV2NFenJDTUZCSXlXR2dHUT09

Meeting ID: 932 5795 8274

Passcode: 976191


Semana de 06/02 a 12/02
Tese de Doutorado
07/02
An excursion in the dynamics of flexible beams: from modal analysis to nonlinear modes
Gustavo Brattstroem Wagner, PUC-Rio

Data: 07/02/2022 às 15h e 0min
Local: por acesso remoto


Orientador: Rubens Sampaio e Roberta Lima
Área de Concentração: Mecânica Aplicada

Resumo

Flexible beams are becoming ubiquitous in several industrial applications, as new projects often aim for lighter and longer structures. This fact is directly related to the new challenging demands on structural performances, or it is a simple consequence of the engagement of industries in cost reduction programs (usage of less material). Flexible beams are usually modeled under the assumption of large displacements, finite rotations, but with small strains. Such hypotheses allow the equation of motion to be built using co-rotational finite elements. The co-rotational formulation decomposes the total motion of a flexible structure into two parts: a rigid body displacement and an elastic (small) deformation. This way, the geometric nonlinearity caused by the large displacements and rotations of the beam's cross sections can be efficiently computed. One of the novelties of this thesis is the direct usage of the equation of motion generated by a co-rotational finite element formulation in the computation of nonlinear normal modes (NNM). So far, most of the dynamic analyses with co-rotation finite element models were restricted to numerical integrations of the equation of motion. The knowledge of NNMs can be beneficial in the analysis of any nonlinear structure since it allows a thoroughly understanding of the vibratory response in the nonlinear regime. They can be used, for example, to predict a hardening/softening behavior, a localization of the responses, the interactions between modes, the existence of isolas, etc. The Rosenberg’s definition of NNM as periodic solutions (non-necessarily synchronous motion) is adopted here. The Harmonic Balance method and the Shooting methods are presented and used to compute periodic solutions of nonlinear systems. A numerical path continuation scheme is implemented to efficiently compute NNMs at different energy levels. Numerical examples show the capability of the proposed method when applied to co-rotational beam elements.

Link da defesa:
https://puc-rio.zoom.us/j/97235967592?pwd=Q205cUpEeU1xUDhpcTZ0ZVJ2Y09lUT09