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Calculation of Interfacial Tension in Water-Methane System at High Pressures Using Molecular Simulation
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Cyrus (Supervisor) ; Taghikhani, Vahid (Supervisor) ; Robert, Marc (Supervisor)
Abstract
Interfacial tension has wide application in surface engineering and specially oil and gas industry. One has to do work to transfer a molecule from bulk to the surface of a fluid. The amount of this work is proportional to Interfacial tension.Molecular simulation is a fundumental approach for calculating the thermophisycal properties of matter such asInterfacial tension.In this thesis we have investigated the effect of pressure and temperature on surface tension of pure water and interfacial tension of Water-Methane system. The TIP4P potential model was used for Water molecules and OPLS for Methane molecules. In the first part, Water heat capacity and Methane density were calculated for...
Investigation the Optimum Condition for Gas Injection into the Oil Reservoirs by Measuring the Interfacial Tension
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Cyrus (Supervisor) ; Robert, Marc (Supervisor) ; Taghikhani, Vahid (Supervisor)
Abstract
Interfacial Tension (IFT) as a main parameter for gas flooding efficiency in oil reservoirs depends highly on pressure, temperature, and composition of the reservoir fluids. Therefore, it is important to measure this parameter at real reservoir condition for successful field development plan. In this study, an axisymmetric drop shape analysis (ADSA) has been utilized to measure the equilibrium IFTs in crude oil-flue gas systems at different temperatures and pressures. Moreover, minimum miscibility pressures (MMP) of crude oil/flue gas and crude oil/N2 systems at different temperature levels are determined by applying vanishing interfacial tension (VIT) technique. Then, the effect of oil...
Search for Missing Baryons Through Scintillation
, Ph.D. Dissertation Sharif University of Technology ; Moniez, Marc (Supervisor) ; Rahvar, Sohrab (Supervisor)
Abstract
Aims: Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected at a longer time scale when the light of remote stars crosses an interstellar molecular cloud, but it has never been observed at optical wavelength. In a favorable case, the light of a background star can be subject to stochastic fluctuations on the order of a few percent at a characteristic time scale of a few minutes. Our ultimate aim is to discover or exclude these scintillation effects to estimate the contribution of molecular hydrogen to the Galactic baryonic hidden mass. This feasibility study is a pathfinder toward an observational strategy to search for scintillation, probing...
A comprehensive study on CO2 solubility in brine: Thermodynamic-based and neural network modeling
,
Article
Fluid Phase Equilibria
;
Volume 403
,
October
,
2015
,
Pages 153-159
;
03783812 (ISSN)
; Salami, H
; Taghikhani, V
; Robert, M. A
;
Sharif University of Technology
Elsevier
2015
Abstract
Phase equilibrium data are required to estimate the capacity of a geological formation to sequester CO2 . In this paper, a comprehensive study, including both thermodynamic and neural network modeling, is performed on CO2 solubility in brine. Brine is approximated by a NaCl solution. The Redlich-Kwong equation of state and Pitzer expansion are used to develop the thermodynamic model. The equation of state constants are adjusted by genetic algorithm optimization. A novel approach based on a neural network model is utilized as well. The temperature range in which the presented model is valid is 283-383K, and for pressure is 0-600bar, covering the temperature and pressure...
Stabilities of some 2-(para-substituted-phenyl)-4,4,5,5-tetramethyl-1,3-dioxolanes relative to their conjugate dioxolenium ions, radicals and carbanions as determined by thermodynamics for hydride and electron transfer in solution [electronic resource]
, Article Journal of Physical Organic Chemistry ; Volume 7, Issue 12, pages 663–671, December 1994 ; Flowers, Robert A ; Meekhof, Alison E ; Pourjavadi, Ali ; Walek, Stuart A ; Sharif University of Technology
Abstract
A calorimetric method is described for the determination of the hydride affinities, ΔHmath image(R+) of seven dioxolenium ions from the title compounds and also tropylium, trityl and 9-phenyl xanthylium cations by hydride transfer to the carbocations from BH3CN−. Cyclic voltammetric methods yield free energies for reduction of the cations to the conjugate radicals and to the carbanions. The ΔHmath image(R+) values correlate well with the first reduction potentials of the cations
Solvation free energy and solubility of acetaminophen and ibuprofen in supercritical carbon dioxide: Impact of the solvent model
, Article Journal of Supercritical Fluids ; Volume 109 , 2016 , Pages 166-176 ; 08968446 (ISSN) ; Ghotbi, C ; Jahanbin Sardroodi, J ; Karimi Sabet, J ; Robert, M. A ; Sharif University of Technology
Elsevier
2016
Abstract
Classical molecular dynamics simulations are used to compute the solvation free energy of two pharmaceutical solids, namely ibuprofen and acetaminophen in carbon dioxide (CO2), over the density range of interest in supercritical processes. In order to examine the influence of the solvent model on the resulting free energies, three popular CO2 models (Zhang, EPM2, and TraPPE) are studied. Relatively large discrepancies for the solvation free energy exist between these CO2 models, suggesting that the former is sensitive to the different balances between dispersive and electrostatic forces used in these models. In particular, for the solvation of the highly polar (dipole moment of ∼5.2 Debye)...