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Zhaoyan Sun - One of the best experts on this subject based on the ideXlab platform.

  • structure Compressibility Factor and dynamics of highly size asymmetric binary hard disk liquids
    Journal of Chemical Physics, 2012
    Co-Authors: Zhaoyan Sun
    Abstract:

    By using event-driven molecular dynamics simulation, we investigate effects of varying the area fraction of the smaller component on structure, Compressibility Factor, and dynamics of the highly size-asymmetric binary hard-disk liquids. We find that the static pair correlations of the large disks are only weakly perturbed by adding small disks. The higher-order static correlations of the large disks, by contrast, can be strongly affected. Accordingly, the static correlation length deduced from the bond-orientation correlation functions first decreases significantly and then tends to reach a plateau as the area fraction of the small disks increases. The Compressibility Factor of the system first decreases and then increases upon increasing the area fraction of the small disks and separating different contributions to it allows to rationalize this non-monotonic phenomenon. Furthermore, adding small disks can influence dynamics of the system in quantitative and qualitative ways. For the large disks, the stru...

  • structure Compressibility Factor and dynamics of highly size asymmetric binary hard disk liquids
    arXiv: Soft Condensed Matter, 2012
    Co-Authors: Zhaoyan Sun
    Abstract:

    By using event-driven molecular dynamics simulation, we investigate effects of varying the area fraction of the smaller component on structure, Compressibility Factor and dynamics of the highly size-asymmetric binary hard-disk liquids. We find that the static pair correlations of the large disks are only weakly perturbed by adding small disks. The higher-order static correlations of the large disks, by contrast, can be strongly affected. The Compressibility Factor of the system first decreases and then increases upon increasing the area fraction of the small disks and separating different contributions to it allows to rationalize this non-monotonic phenomenon. Furthermore, adding small disks can influence dynamics of the system in quantitative and qualitative ways. For the large disks, the structural relaxation time increases monotonically with increasing the area fraction of the small disks at low and moderate area fractions of the large disks. In particular, "reentrant" behavior appears at sufficiently high area fractions of the large disks, strongly resembling the reentrant glass transition in short-ranged attractive colloids and the inverted glass transition in binary hard spheres with large size disparity. By tuning the area fraction of the small disks, relaxation process for the small disks shows concave-to-convex crossover and logarithmic decay behavior, as found in other binary mixtures with large size disparity. Moreover, diffusion of both species is suppressed by adding small disks. Long-time diffusion for the small disks shows power-law-like behavior at sufficiently high area fractions of the small disks, which implies precursors of a glass transition for the large disks and a localization transition for the small disks. Therefore, our results demonstrate the generic dynamic features in highly size-asymmetric binary mixtures.

Amir H Mohammadi - One of the best experts on this subject based on the ideXlab platform.

  • application of wilcoxon generalized radial basis function network for prediction of natural gas Compressibility Factor
    Journal of The Taiwan Institute of Chemical Engineers, 2015
    Co-Authors: Mohammadhadi Shateri, Abdolhossein Hemmatisarapardeh, Shohreh Ghorbani, Amir H Mohammadi
    Abstract:

    Gas Compressibility Factor is necessary in most of chemical and petroleum engineering calculations. Accurate and fast calculation of this property is of a vital importance in a large number of simulators used in petroleum and gas engineering. In this study, a large data bank (978 data points), covering a wide range of natural gases, was collected from open literature sources. Afterwards, one of the newest and most powerful modeling approach, namely Wilcoxon generalized radial basis function network (WGRBFN) was employed to predict the Compressibility Factor of natural gases. The results obtained from the proposed model were compared to those of nine empirical correlations and five equations of state. Statistical and graphical error analyses demonstrated that the developed model can satisFactorily predict the Compressibility Factor of natural gases with an average absolute percent relative error of 2.3%. Moreover, it was demonstrated that the proposed model outperforms all of the studied empirical correlations and equations of state. Finally, to identify the probable outliers the Leverage approach was performed. All of the experimental data seem to be reliable except 2%. Therefore, the developed model is reliable for the prediction of natural gas Compressibility Factor in its applicability domain.

  • efficient estimation of natural gas Compressibility Factor using a rigorous method
    Journal of Natural Gas Science and Engineering, 2014
    Co-Authors: Amir Fayazi, Milad Arabloo, Amir H Mohammadi
    Abstract:

    Abstract The Compressibility Factor (Z-Factor) of natural gases is necessary in many gas reservoir engineering calculations. Accurate determination of this parameter is of crucial need and challenges a large number of used simulators in petroleum engineering. Although numerous studies for prediction of gas Compressibility Factor have been reported in the literature, the accurate prediction of this parameter has been a topic of debate in the literature. For this purpose, a new soft computing approach namely, least square support vector machine (LSSVM) modeling optimized with coupled simulated annealing optimization technique is implemented. The model is developed and tested using a large database consisting of more than 2200 samples of sour and sweet gas compositions. The developed model can predict the natural gas Compressibility Factor as a function of the gas composition (mole percent of C1–C7+, H2S, CO2, and N2), molecular weight of the C7+, pressure and temperature. The calculated Z-Factor values by developed intelligent model are also compared with predictions of other well-known empirical correlations. Statistical error analysis shows that the developed LSSVM model outperforms all existing predictive models with average absolute relative error of 0.19% and correlation coefficient of 0.999. Results from present study show that implementation of LSSVM can lead to more accurate and reliable estimation of natural gas Compressibility Factor.

  • Prediction of sour gas Compressibility Factor using an intelligent approach
    Fuel Processing Technology, 2013
    Co-Authors: Arash Kamari, Abdolhossein Hemmati-sarapardeh, Seyed-morteza Mirabbasi, Mohammad Nikookar, Amir H Mohammadi
    Abstract:

    Abstract Compressibility Factor ( z -Factor) values of natural gasses are essential in most petroleum and chemical engineering calculations. The most common sources of z -Factor values are laboratory experiments, empirical correlations and equations of state methods. Necessity arises when there is no available experimental data for the required composition, pressure and temperature conditions. Introduced here is a technique to predict z -Factor values of natural gasses, sour reservoir gasses and pure substances. In this communication, a novel mathematical-based approach was proposed to develop reliable model for prediction of Compressibility Factor of sour and natural gas. A robust soft computing approach namely least square support vector machine (LSSVM) modeling optimized with coupled simulated annealing (CSA) optimization tool was proposed. To evaluate the performance and accuracy of this model, statistical and graphical error analyses have been used simultaneously. Moreover, comparative studies have been conducted between this model and nine empirical correlations and equations of state. The obtained results demonstrated that the proposed CSA-LSSVM model is more robust, reliable and efficient than the existing correlations and equations of state for prediction of z -Factor of sour and natural gasses.

G A Martynov - One of the best experts on this subject based on the ideXlab platform.

  • corridor of existence of thermodynamically consistent solution of the ornstein zernike equation
    Journal of Chemical Physics, 2007
    Co-Authors: V S Vorobev, G A Martynov
    Abstract:

    We obtain the exact equation for a correction to the Ornstein-Zernike (OZ) equation based on the assumption of the uniqueness of thermodynamical functions. We show that this equation is reduced to a differential equation with one arbitrary parameter for the hard sphere model. The Compressibility Factor within narrow limits of this parameter variation can either coincide with one of the formulas obtained on the basis of analytical solutions of the OZ equation or assume all intermediate values lying in a corridor between these solutions. In particular, we find the value of this parameter when the thermodynamically consistent Compressibility Factor corresponds to the Carnahan-Stirling formula.

  • the unit Compressibility Factor and critical parameters of mercury
    Chemical Physics Letters, 2005
    Co-Authors: E M Apfelbaum, V S Vorobev, G A Martynov
    Abstract:

    Abstract We demonstrate for the first time that the curve corresponding to a unit Compressibility Factor (Z = 1) for mercury constructed on the basis of experimental data in the density–temperature plane is the straight line, as it is the case for many non-metallic substances. Using different approaches, we estimate the mercury critical parameters and compare them with experimental data taking into account this fact.

  • virial expansion providing of the linearity for a unit Compressibility Factor
    Journal of Physical Chemistry A, 2004
    Co-Authors: E M Apfelbaum, V S Vorobev, G A Martynov
    Abstract:

    We show that the law of linearity for a unit Compressibility Factor testifying a lot of experimental data for many substances can be provided by appropriate procedure following from the rigorous consequences of statistical mechanics, namely, the virial expansion. An equation of state that includes the terms up to the fourth power of density is obtained by using second and third virial coefficients. The critical point parameters, phase densities, and pressure along the liquid-gas coexistence curve for the Lennard-Jones (6-12) (LJ) and Buckingham (exp6) potentials are defined. The results corresponding to the LJ potentials are in good agreement with the solution of integral equations and simulation results. For the Buckingham potentials, our predictions agree well with the experimental data for the group of real substances, satisfying the law of corresponding states.

V S Vorobev - One of the best experts on this subject based on the ideXlab platform.

  • the line of the unit Compressibility Factor zeno line for crystal states
    Journal of Physical Chemistry B, 2020
    Co-Authors: E M Apfelbaum, V S Vorobev
    Abstract:

    We study the behavior of the line of the unit Compressibility Factor (Zeno-line) in crystalline states. We used the Lennard-Jones system, experimental P–V–T data for a number of substances, and the...

  • corridor of existence of thermodynamically consistent solution of the ornstein zernike equation
    Journal of Chemical Physics, 2007
    Co-Authors: V S Vorobev, G A Martynov
    Abstract:

    We obtain the exact equation for a correction to the Ornstein-Zernike (OZ) equation based on the assumption of the uniqueness of thermodynamical functions. We show that this equation is reduced to a differential equation with one arbitrary parameter for the hard sphere model. The Compressibility Factor within narrow limits of this parameter variation can either coincide with one of the formulas obtained on the basis of analytical solutions of the OZ equation or assume all intermediate values lying in a corridor between these solutions. In particular, we find the value of this parameter when the thermodynamically consistent Compressibility Factor corresponds to the Carnahan-Stirling formula.

  • the unit Compressibility Factor and critical parameters of mercury
    Chemical Physics Letters, 2005
    Co-Authors: E M Apfelbaum, V S Vorobev, G A Martynov
    Abstract:

    Abstract We demonstrate for the first time that the curve corresponding to a unit Compressibility Factor (Z = 1) for mercury constructed on the basis of experimental data in the density–temperature plane is the straight line, as it is the case for many non-metallic substances. Using different approaches, we estimate the mercury critical parameters and compare them with experimental data taking into account this fact.

  • virial expansion providing of the linearity for a unit Compressibility Factor
    Journal of Physical Chemistry A, 2004
    Co-Authors: E M Apfelbaum, V S Vorobev, G A Martynov
    Abstract:

    We show that the law of linearity for a unit Compressibility Factor testifying a lot of experimental data for many substances can be provided by appropriate procedure following from the rigorous consequences of statistical mechanics, namely, the virial expansion. An equation of state that includes the terms up to the fourth power of density is obtained by using second and third virial coefficients. The critical point parameters, phase densities, and pressure along the liquid-gas coexistence curve for the Lennard-Jones (6-12) (LJ) and Buckingham (exp6) potentials are defined. The results corresponding to the LJ potentials are in good agreement with the solution of integral equations and simulation results. For the Buckingham potentials, our predictions agree well with the experimental data for the group of real substances, satisfying the law of corresponding states.

Alireza Bahadori - One of the best experts on this subject based on the ideXlab platform.

  • carbon dioxide Compressibility Factor determination using a robust intelligent method
    Journal of Supercritical Fluids, 2015
    Co-Authors: Erfan Mohagheghian, Alireza Bahadori, Lesley A James
    Abstract:

    Abstract Owing to the demanding applications and wide uses of supercritical carbon dioxide in oil, gas and chemical industries, fast and precise estimation of carbon dioxide Compressibility Factor is of a vital significance in order to be imported into the relevant industrial simulators. In this study, a data bank covering wide range of temperature and pressure was gathered from open literature. Afterwards, a rigorous novel approach, namely least square support vector machine (LSSVM) optimized with coupled simulated annealing (CSA) was proposed to develop a reliable and robust model for the prediction of Compressibility Factor of carbon dioxide. Reduced temperature and pressure are the inputs of the model. 80% of the dataset was used for training the model and the remaining 20% was used to evaluate its accuracy and reliability. Statistical and graphical error analyses have been conducted to investigate the performance of the model and the obtained results from the proposed model have been compared with those of six equations of state, REFPROP package and two correlations. It was demonstrated that the proposed CSA–LSSVM model is more efficient and reliable than all of the studied empirical correlations, equations of state and the software package, hence it can be utilized confidently for the prediction of carbon dioxide Compressibility Factor.

  • Rapidly Estimating Natural Gas Compressibility Factor
    Journal of Natural Gas Chemistry, 2007
    Co-Authors: Alireza Bahadori, Saeid Mokhatab, Brian F. Towler
    Abstract:

    Abstract Natural gases containing sour components exhibit different gas Compressibility Factor (Z) behavior than do sweet gases. Therefore, a new accurate method should be developed to account for these differences. Several methods are available today for calculating the Z-Factor from an equation of state. However, these equations are more complex than the foregoing correlations, involving a large number of parameters, which require more complicated and longer computations. The aim of this study is to develop a simplified calculation method for a rapid estimating Z-Factor for sour natural gases containing as much as 90% total acid gas. In this article, two new correlations are first presented for calculating the pseudocritical pressure and temperature of the gas mixture as a function of the gas specific gravity. Then, a simple correlation on the basis of the standard gas Compressibility Factor chart is introduced for a quick estimation of sweet gases' Compressibility Factor as a function of reduced pressure and temperature. Finally, a new corrective term related to the mole fractions of carbon dioxide and hydrogen sulfide is developed.