The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Joachim Gross - One of the best experts on this subject based on the ideXlab platform.
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grand canonical monte carlo simulations guided by an analytic equation of state transferable anisotropic mie potentials for ethers
Journal of Physical Chemistry B, 2015Co-Authors: Andrea Hemmen, Athanassios Z Panagiotopoulos, Joachim GrossAbstract:In this study, we propose using an analytical equation of state for guiding molecular simulations in the grand canonical ensemble. Molecular simulations in the grand canonical ensemble deliver Phase equilibrium properties with low statistical uncertainty. The entire Phase Envelope can be obtained when histograms of several simulations along the Phase Envelope are combined. In this study, we explore the use of an analytical equation of state for defining chemical potentials, temperatures, and intervals of molecule numbers for simulations in the grand canonical ensemble, such that the Phase Envelope is traced. We limit particle numbers to intervals and ensure even sampling of molecule numbers in each interval by applying a bias potential determined from transition-matrix sampling. The methodology is described for pure components and binary mixtures. We apply the simulation method to develop parameters of the transferable anisotropic Mie (TAMie) force field for ethers. We find that the partial charges optimi...
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Grand Canonical Monte Carlo Simulations Guided by an Analytic Equation of State—Transferable Anisotropic Mie Potentials for Ethers
The journal of physical chemistry. B, 2015Co-Authors: Andrea Hemmen, Athanassios Z Panagiotopoulos, Joachim GrossAbstract:In this study, we propose using an analytical equation of state for guiding molecular simulations in the grand canonical ensemble. Molecular simulations in the grand canonical ensemble deliver Phase equilibrium properties with low statistical uncertainty. The entire Phase Envelope can be obtained when histograms of several simulations along the Phase Envelope are combined. In this study, we explore the use of an analytical equation of state for defining chemical potentials, temperatures, and intervals of molecule numbers for simulations in the grand canonical ensemble, such that the Phase Envelope is traced. We limit particle numbers to intervals and ensure even sampling of molecule numbers in each interval by applying a bias potential determined from transition-matrix sampling. The methodology is described for pure components and binary mixtures. We apply the simulation method to develop parameters of the transferable anisotropic Mie (TAMie) force field for ethers. We find that the partial charges optimi...
Athanassios Z Panagiotopoulos - One of the best experts on this subject based on the ideXlab platform.
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grand canonical monte carlo simulations guided by an analytic equation of state transferable anisotropic mie potentials for ethers
Journal of Physical Chemistry B, 2015Co-Authors: Andrea Hemmen, Athanassios Z Panagiotopoulos, Joachim GrossAbstract:In this study, we propose using an analytical equation of state for guiding molecular simulations in the grand canonical ensemble. Molecular simulations in the grand canonical ensemble deliver Phase equilibrium properties with low statistical uncertainty. The entire Phase Envelope can be obtained when histograms of several simulations along the Phase Envelope are combined. In this study, we explore the use of an analytical equation of state for defining chemical potentials, temperatures, and intervals of molecule numbers for simulations in the grand canonical ensemble, such that the Phase Envelope is traced. We limit particle numbers to intervals and ensure even sampling of molecule numbers in each interval by applying a bias potential determined from transition-matrix sampling. The methodology is described for pure components and binary mixtures. We apply the simulation method to develop parameters of the transferable anisotropic Mie (TAMie) force field for ethers. We find that the partial charges optimi...
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Grand Canonical Monte Carlo Simulations Guided by an Analytic Equation of State—Transferable Anisotropic Mie Potentials for Ethers
The journal of physical chemistry. B, 2015Co-Authors: Andrea Hemmen, Athanassios Z Panagiotopoulos, Joachim GrossAbstract:In this study, we propose using an analytical equation of state for guiding molecular simulations in the grand canonical ensemble. Molecular simulations in the grand canonical ensemble deliver Phase equilibrium properties with low statistical uncertainty. The entire Phase Envelope can be obtained when histograms of several simulations along the Phase Envelope are combined. In this study, we explore the use of an analytical equation of state for defining chemical potentials, temperatures, and intervals of molecule numbers for simulations in the grand canonical ensemble, such that the Phase Envelope is traced. We limit particle numbers to intervals and ensure even sampling of molecule numbers in each interval by applying a bias potential determined from transition-matrix sampling. The methodology is described for pure components and binary mixtures. We apply the simulation method to develop parameters of the transferable anisotropic Mie (TAMie) force field for ethers. We find that the partial charges optimi...
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Phase behavior of the Lattice Restricted Primitive Model with nearest-neighbor exclusion
The Journal of chemical physics, 2006Co-Authors: Alexandre Diehl, Athanassios Z PanagiotopoulosAbstract:The global Phase behavior of the lattice restricted primitive model with nearest neighbor exclusion has been studied by grand canonical Monte Carlo simulations. The Phase diagram is dominated by a fluid (or charge-disordered solid) to charge-ordered solid transition that terminates at the maximum density, $\rho^*_{max}=\sqrt2$ and reduced temperature $T^*\approx0.29$. At that point, there is a first-order Phase transition between two Phases of the same density, one charge-ordered and the other charge-disordered. The liquid-vapor transition for the model is metastable, lying entirely within the fluid-solid Phase Envelope.
Andrea Hemmen - One of the best experts on this subject based on the ideXlab platform.
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grand canonical monte carlo simulations guided by an analytic equation of state transferable anisotropic mie potentials for ethers
Journal of Physical Chemistry B, 2015Co-Authors: Andrea Hemmen, Athanassios Z Panagiotopoulos, Joachim GrossAbstract:In this study, we propose using an analytical equation of state for guiding molecular simulations in the grand canonical ensemble. Molecular simulations in the grand canonical ensemble deliver Phase equilibrium properties with low statistical uncertainty. The entire Phase Envelope can be obtained when histograms of several simulations along the Phase Envelope are combined. In this study, we explore the use of an analytical equation of state for defining chemical potentials, temperatures, and intervals of molecule numbers for simulations in the grand canonical ensemble, such that the Phase Envelope is traced. We limit particle numbers to intervals and ensure even sampling of molecule numbers in each interval by applying a bias potential determined from transition-matrix sampling. The methodology is described for pure components and binary mixtures. We apply the simulation method to develop parameters of the transferable anisotropic Mie (TAMie) force field for ethers. We find that the partial charges optimi...
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Grand Canonical Monte Carlo Simulations Guided by an Analytic Equation of State—Transferable Anisotropic Mie Potentials for Ethers
The journal of physical chemistry. B, 2015Co-Authors: Andrea Hemmen, Athanassios Z Panagiotopoulos, Joachim GrossAbstract:In this study, we propose using an analytical equation of state for guiding molecular simulations in the grand canonical ensemble. Molecular simulations in the grand canonical ensemble deliver Phase equilibrium properties with low statistical uncertainty. The entire Phase Envelope can be obtained when histograms of several simulations along the Phase Envelope are combined. In this study, we explore the use of an analytical equation of state for defining chemical potentials, temperatures, and intervals of molecule numbers for simulations in the grand canonical ensemble, such that the Phase Envelope is traced. We limit particle numbers to intervals and ensure even sampling of molecule numbers in each interval by applying a bias potential determined from transition-matrix sampling. The methodology is described for pure components and binary mixtures. We apply the simulation method to develop parameters of the transferable anisotropic Mie (TAMie) force field for ethers. We find that the partial charges optimi...
Dan Vladimir Nichita - One of the best experts on this subject based on the ideXlab platform.
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A simple approximate density-based Phase Envelope construction method
Fluid Phase Equilibria, 2019Co-Authors: Dan Vladimir NichitaAbstract:Abstract A new simple density-based method is proposed for approximate Phase Envelope construction of constant composition multicomponent mixtures. The Phase Envelope is traced in the molar density-temperature plane (with a unique saturation temperature at given mixture molar density) and the pressure is calculated explicitly from the equation of state (EoS). The computational procedure is very easy to implement and a reduced system of only three equations must be solved for three variables (molar densities of feed and incipient Phases and temperature), irrespective of the number of components in the mixture. The EoS must not be solved for volume and the elements of the Jacobian matrix have simple forms; the partial derivatives of fugacity coefficients with respect to compositions are not required. A simple and computationally inexpensive correction procedure highly improves results by updating the reference conditions at each point on the Phase Envelope. Simple equations for calculation of maximum temperature and pressure points are presented. The proposed method was tested for a variety of mixtures, ranging from natural gases to heavy oils, using a general form of two-parameter cubic EoS. For usual (closed) Phase Envelopes, the entire Phase boundary is remarkably well reproduced. Certain unusual (open-shaped, with a bubble point branch extending to infinity) Phase Envelopes are also entirely traced up to very high pressures, while in certain cases the method fails at low temperatures (where the approximation of equilibrium constants becomes inadequate), but provides an excellent approximation for a wide temperature range. The proposed method is not dependent of the thermodynamic model (any pressure-explicit EoS can be used), it is recommended for mixtures with many components and it may be particularly attractive for complex EoS.
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Density-based Phase Envelope construction including capillary pressure
Fluid Phase Equilibria, 2019Co-Authors: Dan Vladimir NichitaAbstract:Abstract A recently proposed density-based Phase Envelope construction method (Nichita, Fluid Phase Equilib. 478, 100–113, 2018) is adapted to account for capillary effects. The set of saturation point equations is selected such as both the zero tangent plane distance (TPD) function (in terms of component molar densities and temperature) and the Young-Laplace equation are honored. The set of variables and potential specifications includes mixture molar density, temperature and the modified equilibrium constants (defined as the ratios of reference to incipient Phase component molar density). The number of equations and the variables are the same as in the bulk fluid case. The density-based method including capillary pressure is not dependent on the thermodynamic model; any pressure-explicit equation of state and volume-explicit interfacial tension model can be used. The equation of state (EoS) must not be solved for volume and the elements of the Jacobian matrix have simpler expressions than those in conventional (pressure-based) methods. A code for Phase Envelope construction of bulk fluids can be easily modified by adding the capillary terms to the residual functions and Jacobian matrix. The additional partial derivatives of capillary terms have very simple expressions due to the explicit in volume form of the interfacial tension model. Unlike in conventional formulations, negative pressures in the reference Phase can be handled. The proposed method is tested for several hydrocarbon mixtures, ranging from natural gases to heavy oils. As compared to a bulk fluid, under capillary pressure influence the bubble point pressures are suppressed and the dew point locus is expanded, with a shift of cricondentherm points towards higher temperatures. For the mixtures investigated, the computational results are practically identical to those reported in the literature. The computational procedure is robust, there are no problems neither in crossing the critical region (where interfacial tensions are very low) nor at important negative pressures and for very large capillary pressures (of the order of hundreds bar in some test examples).
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Density-based Phase Envelope construction
Fluid Phase Equilibria, 2018Co-Authors: Dan Vladimir NichitaAbstract:Abstract A new density-based Phase Envelope construction procedure is proposed. The equations for two-Phase saturation molar density and temperature computations are established by equating to zero the tangent plane distance (TPD) function in terms of component molar densities and temperature to find a non-trivial set of component molar densities at various specifications: mixture molar density, temperature and the modified equilibrium constants. The latter are defined as the ratios of feed to incipient Phase component molar density. The nonlinear system of equations is solved by the full Newton method. The sequence of calculations is started at some conditions where convergence is easily obtained and an extrapolation procedure provides high quality initial guesses for subsequent calculations. The Phase Envelope is traced in the molar density-temperature plane, where a unique saturation temperature exists at specified mixture molar density; the representation in the pressure-temperature plane is obtained by calculating explicitly the pressure from the equation of state at given temperature and component molar densities on the saturation curve. The equation of state (EoS) must not be solved for volume and the elements of the Jacobian matrix have simpler expressions than their conventional (pressure-based) counterparts. The proposed method is successfully tested for a variety of mixtures, ranging from binary and ternary mixtures to reservoir fluids, exhibiting usual (closed) and unusual Phase Envelopes, such as open-shaped Envelopes characterized by a bubble point branch extending to infinity, branches with negative pressures constructed in a single run (unlike in the conventional case), several branches, double retrograde behavior and swallowtail pattern corresponding to liquid demixing at low temperatures. The proposed method is not dependent of the thermodynamic model and any pressure-explicit equation of state can be used, provided the required partial derivatives of fugacity and pressure with respect to mole numbers, temperature and volume are available.
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Phase Envelope Construction for Mixtures with Many Components
Energy and Fuels, 2007Co-Authors: Dan Vladimir NichitaAbstract:A reduction method for constructing vapor-liquid equilibrium Phase Envelopes with cubic equations of state is presented. The paper describes the calculation procedures for saturation (dewpoint/bubblepoint) pressures and temperatures, quality lines (for given mole fraction or volume fraction of one of the equilibrium Phases), cricondentherm and cricondenbar points, the critical point, and the spinodal. The Phase Envelope construction is fully automatic. The saturation points are calculated throughout the critical region by stepping around the Phase Envelope in pressure or temperature increments. An extrapolation procedure taking advantage of the Jacobian matrix available from a previous step is used. Problem formulation in terms of reduced variables leads to simpler partial derivatives with respect to pressure and temperature. The proposed method is successfully tested for several representative hydrocarbon mixtures with various Phase Envelope shapes.
Paulo Rosa - One of the best experts on this subject based on the ideXlab platform.
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CO2 and temperature effects on the asphaltene Phase Envelope as determined by a quartz crystal resonator
Energy and Fuels, 2014Co-Authors: Felipe Cardoso, Hervé Carrier, Jean-luc Daridon, Jérôme Pauly, Paulo RosaAbstract:Knowledge of the asphaltene Phase Envelope (APE) is crucial for oil companies, especially when enhanced oil recovery is applied. An innovative quartz crystal resonator (QCR) technique was employed to assess the Phase behavior of asphaltene under reservoir conditions. The effect of CO2 injection coupled to temperature changes on the APE of a recombined oil with a very low asphaltene content (0.235% w/w of C7 asphaltene in dead oil) are reported. It has been shown that QCR is an appropriate and highly sensitive nondestructive experimental technique for detecting asphaltene flocculation. Pressure onsets were found to be dependent on the depressurization rate.