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Design of the Modelica Library VehProLib with Non-ideal Gas Models in Engines / Designval av Modelica Biblioteket VehProLib med Icke-Ideal Gasmodell i FörbränningsmotorerAndersson, Conny January 2015 (has links)
This thesis covers the reconstruction and the redesign of the modeling library VehProLib,which is constructed in the modeling language Modelica with help of the modeling toolWolfram SystemModeler. The design choices are discussed and implemented. This thesisalso includes the implementation of a turbocharger package and an initial study of the justificationof the ideal gas law in vehicle modeling. The study is made with help of Van derWaals equation of states as a reference of non-ideal gas model. It will be shown that for themean-value-engine-model, the usage of ideal gas law is justified.
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Molecular Simulation towards Efficient and Representative Subsurface Reservoirs ModelingKadoura, Ahmad Salim 09 1900 (has links)
This dissertation focuses on the application of Monte Carlo (MC) molecular simulation and Molecular Dynamics (MD) in modeling thermodynamics and flow of subsurface reservoir fluids. At first, MC molecular simulation is proposed as a promising method to replace correlations and equations of state in subsurface flow simulators. In order to accelerate MC simulations, a set of early rejection schemes (conservative, hybrid, and non-conservative) in addition to extrapolation methods through reweighting and reconstruction of pre-generated MC Markov chains were developed.
Furthermore, an extensive study was conducted to investigate sorption and transport processes of methane, carbon dioxide, water, and their mixtures in the inorganic part of shale using both MC and MD simulations. These simulations covered a wide range of thermodynamic conditions, pore sizes, and fluid compositions shedding light on several interesting findings. For example, the possibility to have more carbon dioxide adsorbed with more preadsorbed water concentrations at relatively large basal spaces. The dissertation is divided into four chapters. The first chapter corresponds to the introductory part where a brief background about molecular simulation and motivations are given. The second chapter is devoted to discuss the theoretical aspects and methodology of the proposed MC speeding up techniques in addition to the corresponding results leading to the successful multi-scale simulation of the compressible single-phase flow scenario. In chapter 3, the results regarding our extensive study on shale gas at laboratory conditions are reported. At the fourth and last chapter, we end the dissertation with few concluding remarks highlighting the key findings and summarizing the future directions.
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Simulating Gas Blowout In Tropical Shallow WatersLEITE, Fabiana Soares 26 September 2012 (has links)
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Previous issue date: 2012-09-26 / FACEPE / A exploração de óleo e gás vem apresentando um rápido crescimento em
regiões de baixa latitude, mesmo assim pouquíssimos experimentos e
modelagens envolvendo vazamento de gás têm sido publicados pela
comunidade científica. Este estudo foi desenvolvido de modo a aumentar o
conhecimento a respeito do comportamento da pluma de gás durante um
vazamento acidental em águas rasas. Os métodos usados e os resultados
obtidos são apresentados neste estudo, assim como um modelo para
simular o transporte e a dispersão de uma pluma de gás liberada em
águas rasas. Primeiramente, experimentos de campo foram realizados
através da simulação de um vazamento de gás natural a
aproximadamente 30 m de profundidade na costa nordeste do Brasil.
Quatro cenários distintos, com variadas condições de forçantes geofísicas,
foram associados a diferentes fluxos de gás (de 3000 a 9000 L.h-1) e
períodos sazonais (verão e inverno). Num segundo estágio, a análise de
dispersão da pluma de gás foi realizada com os dados obtidos in situ. O
modelo usou um volume de controle lagrangiano para discretização e
simulou a evolução da pluma de gás associando a termodinâmica e o
impacto desta na hidrodinâmica da pluma de gás. De acordo com os
dados coletados, o transporte predominante da corrente ocorreu para sulsudoeste
(nordeste) durante o verão (inverno). A diferença no diâmetro da
pluma ocorreu principalmente na camada mais próxima à superfície. A
pluma de gás deslocou-se para sul-sudoeste no verão e para nordestenorte
durante o inverno. Os fluxos de gás liberados no assoalho oceânico
pareceram não afetar a hidrodinâmica local. O movimento da pluma foi
sempre influenciado pelas forçantes de maré e meteorológica, nesta
ordem. Os resultados de modelagem indicaram que, à medida que a
pluma sobe na coluna de água, a mesma é deslocada horizontalmente na
direção da corrente predominante. A situação extrema estabeleceu um
raio crítico (máximo deslocamento horizontal) da fonte de gás de 35,2 m. A
comparação entre os dados medidos e os calculados mostrou que o
modelo representou satisfatoriamente as principais características da
liberação de gás, tais como o deslocamento, o diâmetro e o tempo de
ascensão da pluma. Apesar das plumas apresentarem a largura média da
mesma ordem de magnitude entre as medições e os cálculos, melhorias
podem aumentar o desempenho do modelo durante o desenvolvimento
inicial das plumas. Dados importantes e únicos foram coletados durante
os vazamentos de gás, os quais contribuíram para a caracterização do
comportamento de diferentes fluxos em diferentes períodos. Os
experimentos forneceram uma base de dados para um modelo
computacional que foi capaz de reproduzir o transporte e a dispersão de
uma pluma de gás no ambiente marinho. O modelo foi capaz de prever o
transporte e destino do gás liberado no ambiente. O mesmo pode,
portanto, ser usado como uma ferramenta para planos de contingência de
vazamentos acidentais de gás no oceano. / Underwater oil and gas exploration has been growing fast in low latitude
regions, even though very few experimental data acquisition and modeling
involving gas release in tropical and shallow waters have been published
by the scientific community. This study was developed to increase the
knowledge concerning the gas behavior during a subsurface blowout in
shallow waters. The methods used and the results obtained from this
study are presented, as well as a model to simulate the transport and
dispersion of a subsurface gas plume released from shallow waters. At
first, field experiments were carried out by simulating a subsurface
blowout with natural gas at approximately 30 m depth in the Northeast
Brazilian coast. Four distinct scenarios with varied conditions of
geophysical forcing were associated with different fluxes (from 3000 to
9000 L.h-1) and seasonal periods (summer and winter). As a second stage,
the analysis of the gas plume dispersion was accomplished with the data
obtained from the above campaigns. The model used a Lagrangian control
volume for discretization and simulated the gas plume evolution,
associating thermodynamics and the impact of the thermodynamics on
the hydrodynamics of the gas plume. The predominant transport occurred
toward the south-southwest (northeast) during the summer (winter)
period. The difference in the plume width occurred mainly in the upper
surface layer. The gas plume displaced toward the south-southwest
(northeast-north) during the summer (winter) period. The gas flow releases
seemed not to affect the local hydrodynamics. The plume movement was
always influenced by the tidal and meteorological forcings, in that order.
The simulation results indicated that, as the gas plume rose in the water
column, the same plume was horizontally displaced toward current
predominant direction. The extreme situation provided a critical radius
(maximum horizontal displacement) from the gas release source of 35.2 m.
The comparison between the measured and the calculated data showed
that the model satisfactorily represented the main features of the gas
release, such as the displacement, diameter and ascending time of the
plume. Although the mean plume widths have the same order of
magnitude between the measurements and the calculations,
improvements may enhance the model’s performance during the earlier
plume development. Important and unique data were collected during
these subsurface releases, which contributed to the characterization of the
behavior of different blowouts in different seasons. The experiments
provided a baseline for a computational model capable of reproducing gas
plume transport and dispersion in the marine environment. The model
was able to predict the gas release transport and fate in the environment.
Thus it can be used as a tool for contingency planning of an accidental
underwater gas release.
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