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Jeannoel Jaubert - One of the best experts on this subject based on the ideXlab platform.

  • on the imperative need to use a consistent α function for the prediction of pure compound supercritical properties with a Cubic Equation of state
    Fluid Phase Equilibria, 2017
    Co-Authors: Yohann Le Guennec, Romain Privat, Silvia Lasala, Jeannoel Jaubert
    Abstract:

    Abstract Since Van der Waals, the attractive term a ( T ) of any Cubic Equation of state is expressed as the product of its value at the critical temperature ( a c ) by the so-called alpha function. Our recent investigations made it however possible to conclude that to get accurate and physically meaningful behaviors in both the subcritical and supercritical domains, it was necessary to work with a consistent α-function, i.e., with an α-function which is positive, decreasing, convex and with a negative third derivative. This paper aims at quantifying the gain of accuracy resulting from the use of a consistent α-function when a Cubic Equation of state is used to calculate the properties of a pure compound in the supercritical region. As a key conclusion, embedding a consistent α-function in a Cubic Equation of state instead of an inconsistent one entails a division by a factor 9 of the deviations between calculated and experimental data.

  • predicting the phase equilibria critical phenomena and mixing enthalpies of binary aqueous systems containing alkanes cycloalkanes aromatics alkenes and gases n2 co2 h2s h2 with the ppr78 Equation of state
    Industrial & Engineering Chemistry Research, 2013
    Co-Authors: Junwei Qian, Romain Privat, Jeannoel Jaubert
    Abstract:

    The phase behavior of water/hydrocarbon mixtures in a wide range of concentrations, temperatures, and pressures is important in a variety of chemical engineering applications. For this reason, the physical understanding and mathematical modeling of these aqueous–organic mixtures constitute a challenging task, both for scientists and for applied engineers. In this work, mutual solubilities, critical loci, and mixing enthalpies of water + hydrocarbon, water + carbon dioxide, water + nitrogen, water + hydrogen sulfide, and water + hydrogen binary mixtures are predicted using the PPR78 Cubic Equation of state (EoS). The extremely nonideal behavior of these systems produces unusual and complex thermodynamic behavior. As an example, such mixtures often exhibit type III phase behavior in the classification scheme of Van Konynenburg and Scott and are characterized by a vapor–liquid critical line which first exhibits a temperature minimum and then extends to temperatures above the critical point of pure water. Suc...

  • enthalpy and heat capacity changes on mixing fundamental aspects and prediction by means of the ppr78 Cubic Equation of state
    Energy & Fuels, 2013
    Co-Authors: Junwei Qian, Romain Privat, Jeannoel Jaubert, Pierre Duchetsuchaux
    Abstract:

    The PPR78 model is a predictive Cubic Equation of state relying on the group-contribution concept. Our previous studies have highlightened its capacity to predict the phase behavior of mixtures containing a large variety of compounds: alkanes, alkenes, aromatic compounds, permanent gases, sulfur compounds, etc. In this paper, it is attempted for the first time to answer the question “can the PPR78 model be safely used in energy-rate balances?”. To do so, the largest possible number of enthalpy of mixing data and isobaric heat capacity of mixing data were collected in the open literature and predicted using the PPR78 model. It is shown that although certainly perfectible, this model generally provides from acceptable to accurate estimations of these properties depending on the nature of the mixtures and the conditions of temperature and pressure as well. Furthermore, this paper proposes some general reflections both on conceptual and practical issues: Is it always possible to claim that the excess enthalpy...

  • characterization of heavy oils 3 prediction of gas injection behavior swelling test multicontact test multiple contact minimum miscibility pressure and multiple contact minimum miscibility enrichment
    Industrial & Engineering Chemistry Research, 1995
    Co-Authors: Jeannoel Jaubert, Evelyne Neau, Laurent Avaullee, Georges Zaborowski
    Abstract:

    The modeling of miscible gas injection into reservoir crude oils was performed using a Cubic Equation of state coupled with a predictive procedure for characterizing the heavy fractions. It is shown that experimental data on the swelling test, multicontact test, slim tube minimum miscibility pressure (MMP), and minimum miscibility enrichment (MME) for 10 different crude oils from different fields are satisfactorily calculated using the predictive characterization. However, in the case of MMP and MME calculations, a significant deviation may appear between predicted and experimental values. Reasons for this discrepancy are discussed. The influence of tuning the Equation of state parameters in the estimation of results for the swelling test is also discussed.

Chorng H Twu - One of the best experts on this subject based on the ideXlab platform.

  • new solid Equation of state combining excess energy mixing rule for solid liquid equilibria
    Aiche Journal, 2003
    Co-Authors: Chorng H Twu, Vince Tassone, Wayne D Sim
    Abstract:

    Crude oil is a mixture of light and heavy hydrocarbon components. The light components in crude oil keep the heavy components soluble in solution. However, the cooling of crude oil below its solidification point leads to the formation of a solid-wax phase. A number of thermodynamically based models have been proposed in the literature for the prediction of wax formation in both crude oils and fuels. Some of these models assume ideal liquid solution behavior. Others are a modification of the regular solution theory or the Flory-Huggins model for activity coefficients, with varying degrees of success. The absence of a proper model in the petroleum industry to describe the liquid-phase non-ideality for mixtures of hydrocarbons with large differences in size is still one of the major problems in solid-liquid equilibrium calculations. A simple methodology is proposed to develop a Cubic Equation of state (CEOS) for the solid phase to allow the accurate calculation of solid-liquid equilibria. The methodology is successfully applied to the Twu-Sim-Tassone (TST) Cubic Equation of state. The solid TST Equation of state is then combined with the TST excess Helmholtz energy mixing rule to handle highly nonideal systems for the accurate prediction of solid-liquid phase equilibria.

  • a new generalized alpha function for a Cubic Equation of state part 1 peng robinson Equation
    Fluid Phase Equilibria, 1995
    Co-Authors: Chorng H Twu, John E Coon, John R Cunningham
    Abstract:

    Abstract A generalized temperature and acentric factor dependent function of the attractive term, called the alpha function, of the Peng-Robinson Cubic Equation of state (PR CEOS) is developed. The approach in this work allows the alpha function to become a linear function of the acentric factor at a constant reduced temperature, not a fourth or sixth order function as suggested by Soave and other researchers. The advantage of a linear function in the acentric factor is obvious in the extrapolation of the alpha function to heavy hydrocarbons, petroleum fractions, and gas condensates. The new generalized alpha function, when used with the PR CEOS, allows the accurate reproduction of the vapor pressure data from the triple point to the critical point for hydrocarbons. The new CEOS provides much more reliable and accurate vapor pressure predictions for light as well as heavy hydrocarbons than the original PR Equation.

  • a Cubic Equation of state with a new alpha function and a new mixing rule
    Fluid Phase Equilibria, 1991
    Co-Authors: Chorng H Twu, David Bluck, John R Cunningham, John E Coon
    Abstract:

    Abstract Twu C.H., Bluck D., Cunningham J.R. and Coon J.E., 1991. A Cubic Equation of state with a new alpha function and a new mixing rule. Fluid Phase Equilibria, 69: 33-50. A new temperature-dependent function (α) for a Cubic Equation of state is proposed. The new α function used in the Cubic Equation of state not only correlates the vapor pressures of pure components, but extrapolates correctly to the supercritical region. The new Cubic Equation of state has been used to accurately describe the vapor pressure and liquid heat capacity for over 1000 chemical components. The accuracy of reproducing the vapor pressure from the triple point to the critical point is generally within the experimental error. A new mixing rule has also been developed for correlating phase equilibrium data. The mixing rule can reproduce the activity coefficients in the infinite dilution region as well as model phase behavior throughout the finite range of concentration. This mixing rule allows the accurate representation of polar/non-polar systems and can be extended to multicomponent systems. The Cubic Equation of state with the proposed new α function and the new mixing rule is applicable to important systems encountered in industrial practice.

Dimitrios P. Tassios - One of the best experts on this subject based on the ideXlab platform.

  • prediction of phase equilibria in binary aqueous systems containing alkanes cycloalkanes and alkenes with the Cubic plus association Equation of state
    Industrial & Engineering Chemistry Research, 1998
    Co-Authors: Iakovos V Yakoumis, Georgios M. Kontogeorgis, Epaminondas Voutsas, Eric M Hendriks, Dimitrios P. Tassios
    Abstract:

    The Cubic-plus-association (CPA) Equation of state (EoS) is applied in this study to binary aqueous mixtures containing hydrocarbons. The CPA EoS combines the Soave−Redlich−Kwong (SRK) Cubic Equation of state for the physical part and perturbation theory for the chemical (association) part. Rigorous expressions for the contribution of the association term to the pressure and to the chemical potential, which do not include any derivatives of the mole fraction of molecules i not bonded at site A (XAi), are presented. Three different association models for water have been considered depending on the number of hydrogen bonding sites per water molecule:  the two-, three-, and four-site models. Successful correlation of both vapor pressures and saturated liquid volumes is obtained with all three models. However, satisfactory correlation results of the mutual solubilities of water/aliphatic hydrocarbon systems are obtained only with the four-site model using a single interaction parameter (kij) in the attractive...

  • an Equation of state for associating fluids
    Industrial & Engineering Chemistry Research, 1996
    Co-Authors: Georgios M. Kontogeorgis, Iakovos V Yakoumis, Epaminondas Voutsas, Dimitrios P. Tassios
    Abstract:

    An Equation of state (EoS) suitable for describing associating fluids is presented. The Equation combines the simplicity of a Cubic Equation of state (the Soave−Redlich−Kwong), which is used for the physical part and the theoretical background of the perturbation theory employed for the chemical (or association) part. The resulting EoS (Cubic Plus Association) is not Cubic with respect to volume and contains five pure compound parameters which are determined using vapor pressures and saturated liquid densities. Excellent correlations of both vapor pressures and saturated liquid volumes are obtained for primary-alcohols (from methanol up to 1-tridecanol), phenol, tert-butyl alcohol, triethylene glycol, and water. Moreover, excellent prediction of saturated liquid volumes may be obtained from parameters which have been estimated by regressing only vapor pressures. Finally, we suggest a method for reducing the number of adjustable parameters for alcohols to three while maintaining the good correlation of vap...

Thomas R Porter - One of the best experts on this subject based on the ideXlab platform.

  • left atrial volume determination by three dimensional echocardiography reconstruction validation and application of a simplified technique
    Journal of The American Society of Echocardiography, 2002
    Co-Authors: Banthit Khankirawatana, Suwanee Khankirawatana, John Lof, Thomas R Porter
    Abstract:

    Abstract Left atrial (LA) size assessment by anteroposterior dimension is limited in accuracy. Conventional 3-dimensional (3D) reconstruction has been validated, but the process is time-consuming and the 3D system is not widely available. We developed an algorithm to simplify 3D reconstruction of LA on the basis of 3 standard apical views, tested it in 44 hemodynamic stages of 8 open-chest dogs, and compared it with LA volumes assessed by conventional 3D reconstruction. Simplified 3D reconstruction provided an accurate LA volume measurement (y = 0.93x + 0.7, r = 0.95, standard error of the estimate [SEE] = 3.6) with more than 60% of time saved. Cubic Equation of anteroposterior dimension and biplane modified Simpson's method were less accurate (for biplane modified Simpson's method, y=0.8x + 2.6, r=0.88, SEE=5.0; for Cubic Equation of anteroposterior dimension, y=0.65x + 2.6, r=0.76, SEE=8.2). Without the need for a 3D-imaging acquisition tool, simplified 3D reconstruction can be applied in the clinical setting for LA size quantitation with significant time saved. (J Am Soc Echocardiogr 2002;15:1051-6.)

  • left atrial volume determination by three dimensional echocardiography reconstruction validation and application of a simplified technique
    Journal of The American Society of Echocardiography, 2002
    Co-Authors: Banthit Khankirawatana, Suwanee Khankirawatana, Thomas R Porter
    Abstract:

    Abstract Left atrial (LA) size assessment by anteroposterior dimension is limited in accuracy. Conventional 3-dimensional (3D) reconstruction has been validated, but the process is time-consuming and the 3D system is not widely available. We developed an algorithm to simplify 3D reconstruction of LA on the basis of 3 standard apical views, tested it in 44 hemodynamic stages of 8 open-chest dogs, and compared it with LA volumes assessed by conventional 3D reconstruction. Simplified 3D reconstruction provided an accurate LA volume measurement (y = 0.93x + 0.7, r = 0.95, standard error of the estimate [SEE] = 3.6) with more than 60% of time saved. Cubic Equation of anteroposterior dimension and biplane modified Simpson's method were less accurate (for biplane modified Simpson's method, y=0.8x + 2.6, r=0.88, SEE=5.0; for Cubic Equation of anteroposterior dimension, y=0.65x + 2.6, r=0.76, SEE=8.2). Without the need for a 3D-imaging acquisition tool, simplified 3D reconstruction can be applied in the clinical setting for LA size quantitation with significant time saved. (J Am Soc Echocardiogr 2002;15:1051-6.)

Celine Houriez - One of the best experts on this subject based on the ideXlab platform.

  • experimental measurements and modelling of vapour liquid equilibrium of 2 3 3 3 tetrafluoropropene r 1234yf 1 1 1 2 2 pentafluoropropane r 245cb system
    International Journal of Refrigeration-revue Internationale Du Froid, 2019
    Co-Authors: Alain Valtz, Jamal El Abbadi, Christophe Coquelet, Celine Houriez
    Abstract:

    Abstract Isothermal vapour-liquid equilibrium (VLE) of the R-1234yf+R-245cb binary system were measured using a “static-analytic” apparatus at temperatures from 283.39 to 343.27 K. The data measured were compared with literature data for conformity checking. Albeit both VLE measurement sets are in good accordance, an unexpected behaviour was observed for the relative volatility calculated on the basis of the literature data. The thermodynamic model used for the calculations reproduces very well R-1234yf+R-245cb VLE data, and is based on a 3-parameter Cubic Equation of state (denoted by NEoS). This Cubic Equation of state was associated with the Mathias–Copeman alpha function and van der Waals mixing rules. Comparisons were also done with Peng–Robinson EoS with similar alpha function and mixing rules.