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Mohammad Almasi - One of the best experts on this subject based on the ideXlab platform.
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Experimental and modeling study of diisopropyl ether and 2-alkanol; PC-SAFT model and Free Volume Theory
The Journal of Chemical Thermodynamics, 2020Co-Authors: Simin Ahmadi, Mohammad AlmasiAbstract:Abstract In the present study, with the aim to discover the governing interactions in binary mixtures containing diisopropyl ether and short-range 2-alkanol (from 2-propanol to 2-hexanol), experimental values of density and viscosity at temperature range 293.15 K–323.15 K were reported. From these data, values of excess molar Volume, partial molar Volume, and viscosity deviation for mentioned systems were calculated. Findings show that strong interactions occur among unlike molecules while increasing in the carbon chain length of 2-alkanol, reinforces the interactions. Also, the perturbed-chain SAFT (PC-SAFT) equation of state was implemented to study the density and partial molar Volume of binary mixtures. Combination of this model with Free Volume Theory was applied for prediction of binary viscosities. Maximum deviation in AAD for density correlation regarding PC-SAFT model was 1.21%, and for viscosity calculation was 2.19%.
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correlation studies of cyclohexanone c5 c10 alkan 1 ol binary mixtures pc saft model and Free Volume Theory
Journal of Chemical & Engineering Data, 2018Co-Authors: Bahman Sarkoohaki, Mohammad Almasi, Mehrnoosh KarimkhaniAbstract:In this article the behavior of cyclohexanone + 1-alkanol, namely, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol, binary mixtures through the density and viscosity measurements has been studied as a function of composition and within the temperature range of 293.15–323.15 K. The excess molar Volume and viscosity deviations have been calculated and fitted by the Redlich–Kister polynomial equation. For binary mixtures of cyclohexanone + 1-pentanol, values of excess molar Volume are negative and for other mixtures are positive. For all binary systems viscosity deviations are negative and increase with the alkyl chain of alcohol. The results provide information on the interactions among the molecules in the pure state as well as the binary liquid mixtures. The measured densities and viscosities have been applied to test the applicability of the PC-SAFT and Free Volume models.
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Correlation Studies of Cyclohexanone/(C5–C10) Alkan-1-ol Binary Mixtures: PC-SAFT Model and Free Volume Theory
2018Co-Authors: Bahman Sarkoohaki, Mohammad Almasi, Mehrnoosh KarimkhaniAbstract:In this article the behavior of cyclohexanone + 1-alkanol, namely, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol, binary mixtures through the density and viscosity measurements has been studied as a function of composition and within the temperature range of 293.15–323.15 K. The excess molar Volume and viscosity deviations have been calculated and fitted by the Redlich–Kister polynomial equation. For binary mixtures of cyclohexanone + 1-pentanol, values of excess molar Volume are negative and for other mixtures are positive. For all binary systems viscosity deviations are negative and increase with the alkyl chain of alcohol. The results provide information on the interactions among the molecules in the pure state as well as the binary liquid mixtures. The measured densities and viscosities have been applied to test the applicability of the PC-SAFT and Free Volume models
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densities and viscosities of binary mixtures containing ethyl formate and 2 alkanols friction Theory and Free Volume Theory
Journal of Chemical & Engineering Data, 2015Co-Authors: Mohammad AlmasiAbstract:The present study reports the densities and viscosities of mixing at various temperatures [(293.15 to 323.15) K] for mixtures composed of ethyl formate and 2-alkanols (from 2-propanol to 2-pentanol). From these measurements, excess molar Volumes VmE and viscosity deviations Δη were calculated. These results were fitted to Redlich–Kister type polynomials. Positive excess molar Volumes and negative viscosity deviations for studied mixtures indicate that no strong specific interactions occur in the mixtures. The data of viscosities have been used to study the performance of two viscosity models. The evaluated models are friction Theory and Free Volume Theory. Overall two models can describe the fluid viscosity with good accuracy. Results show that the performance of friction Theory for correlating the viscosities is more satisfactory.
Lourdes F Vega - One of the best experts on this subject based on the ideXlab platform.
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Free Volume Theory coupled with soft saft for viscosity calculations comparison with molecular simulation and experimental data
Journal of Physical Chemistry B, 2013Co-Authors: Felix Llovell, R M Marcos, Lourdes F VegaAbstract:The evaluation of phase equilibria and solubility properties through theoretical approaches is a well-known field, where a significant amount of models are able to describe them with a good degree of accuracy. However, the simultaneous calculation of transport properties together with thermodynamic phase properties still remains a challenge, due to the difficulties in describing the behavior of properties like the viscosity of fluids with the same approach. In this work, the Free-Volume Theory (FVT) has been coupled with the soft-SAFT equation for the first time to extend the capabilities of the equation to the calculation of transport properties. The Theory has been first tested using simulation data of the viscosity of the Lennard-Jones (LJ) fluid and LJ chains over a wide range of temperature and pressure. Good agreement has been found at all chain lengths, except for some deviations at near-zero density values. Several trends of the viscosity parameters with the length of the chain are identified, all...
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transport properties of mixtures by the soft saft Free Volume Theory application to mixtures of n alkanes and hydrofluorocarbons
Journal of Physical Chemistry B, 2013Co-Authors: Felix Llovell, R M Marcos, Lourdes F VegaAbstract:In a previous paper (Llovell et al.J. Phys. Chem. B, submitted for publication), the Free-Volume Theory (FVT) was coupled with the soft-SAFT equation of state for the first time to extend the capabilities of the equation to the calculation of transport properties. The equation was tested with molecular simulations and applied to the family of n-alkanes. The capability of the soft-SAFT + FVT treatment is extended here to other chemical families and mixtures. The compositional rules of Wilke (Wilke, C. R.J. Chem. Phys. 1950, 18, 517−519) are used for the diluted term of the viscosity, while the dense term is evaluated using very simple mixing rules to calculate the viscosity parameters. The Theory is then used to predict the vapor–liquid equilibrium and the viscosity of mixtures of nonassociating and associating compounds. The approach is applied to determine the viscosity of a selected group of hydrofluorocarbons, in a similar manner as previously done for n-alkanes. The soft-SAFT molecular parameters are ...
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transport properties of mixtures by the soft saft Free Volume Theory application to mixtures of n alkanes and hydrofluorocarbons
Journal of Physical Chemistry B, 2013Co-Authors: Felix Llovell, R M Marcos, Lourdes F VegaAbstract:In a previous paper (Llovell et al. J. Phys. Chem. B, submitted for publication), the Free-Volume Theory (FVT) was coupled with the soft-SAFT equation of state for the first time to extend the capabilities of the equation to the calculation of transport properties. The equation was tested with molecular simulations and applied to the family of n-alkanes. The capability of the soft-SAFT + FVT treatment is extended here to other chemical families and mixtures. The compositional rules of Wilke (Wilke, C. R. J. Chem. Phys. 1950, 18, 517-519) are used for the diluted term of the viscosity, while the dense term is evaluated using very simple mixing rules to calculate the viscosity parameters. The Theory is then used to predict the vapor-liquid equilibrium and the viscosity of mixtures of nonassociating and associating compounds. The approach is applied to determine the viscosity of a selected group of hydrofluorocarbons, in a similar manner as previously done for n-alkanes. The soft-SAFT molecular parameters are taken from a previous work, fitted to vapor-liquid equilibria experimental data. The application of FVT requires three additional parameters related to the viscosity of the pure fluid. Using a transferable approach, the α parameter is taken from the equivalent n-alkane, while the remaining two parameters B and Lv are fitted to viscosity data of the pure fluid at several isobars. The effect of these parameters is then investigated and compared to those obtained for n-alkanes, in order to better understand their effect on the calculations. Once the pure fluids are well characterized, the vapor-liquid equilibrium and the viscosity of nonassociating and associating mixtures, including n-alkane + n-alkane, hydrofluorocarbon + hydrofluorocarbon, and n-alkane + hydrofluorocarbon mixtures, are calculated. One or two binary parameters are used to account for deviations in the vapor-liquid equilibrium diagram for nonideal mixtures; these parameters are used in a transferable manner to predict the viscosity of the mixtures. Very good agreement with available experimental data is found in all cases, with an average absolute deviation ranging between 1.0% and 5.5%, even when the system presents azeotropy, reinforcing the robustness of the approach.
Byung Chan Eu - One of the best experts on this subject based on the ideXlab platform.
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generic van der waals equation of state for polymers modified Free Volume Theory and the self diffusion coefficient of polymeric liquids
Physica A-statistical Mechanics and Its Applications, 2010Co-Authors: Haidar Sabbagh, Byung Chan EuAbstract:In this paper, a molecular Theory of self-diffusion coefficient is developed for polymeric liquids (melts) on the basis of the integral equation Theory for site–site pair correlation functions, the generic van der Waals equation of state, and the modified Free Volume Theory of diffusion. The integral equations supply the pair correlation functions necessary for the generic van der Waals equation of state, which in turn makes it possible to calculate the self-diffusion coefficient on the basis of the modified Free Volume Theory of diffusion. A random distribution is assumed for minimum Free Volumes for monomers along the chain in the melt. More specifically, a stretched exponential is taken for the distribution function. If the exponents of the distribution function for minimum Free Volumes for monomers are chosen suitably for linear polymer melts of N monomers, the N dependence of the self-diffusion coefficient is N−1 for the small values of N, an exponent predicted by the Rouse Theory, whereas in the range of 2.3≲lnN≲4.5 the N dependence smoothly crosses over to N−2, which is reminiscent of the exponent by the reptation Theory. However, for lnN≳4.5 the N dependence of the self-diffusion coefficient differs from N−2, but gives an N dependence, N−2−δ(0<δ<1), consistent with experiment on polymer melts in the range. For polyethylene δ≈0.48 for the parameters chosen for the stretched exponential. Because the stretched exponential function contains undetermined parameters, the N dependence of diffusion becomes semiempirical, but once the parameters are chosen such that the N dependence of D can be successfully given for a polymer melt, the temperature dependence of the self-diffusion coefficient can be well predicted in comparison with experiment. The Theory is satisfactorily tested against experimental and simulation data on the temperature dependence of D for polyethylene and polystyrene melts.
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voids generic van der waals equation of state and transport coefficients of liquids
Physical Chemistry Chemical Physics, 2007Co-Authors: Byung Chan EuAbstract:In this Perspective, we discuss the role of voids in transport processes in liquids and the manner in which the concept of voids enters the generic van der Waals equation of state and the modified Free Volume Theory. The density fluctuation Theory is then discussed and we show how the density fluctuation Theory can be made a molecular Theory with the help of the modified Free Volume Theory and the generic van der Waals equation of state. The confluence of the aforementioned three theories makes it possible to calculate the transport coefficients of liquids by using the information on the equilibrium pair correlation function, which can be calculated either by an integral equation Theory or Monte Carlo simulations. A number of relations between transport coefficients are also presented, which are derived on the basis of the density fluctuation Theory. Since they can be used to obtain one transport coefficient from another they can be very useful in handling experimental and theoretical data. An application of the modified Free Volume Theory to polymer melts is discussed as an example for a Theory of transport properties of complex liquids.
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excluded Volume in the generic van der waals equation of state and the self diffusion coefficient of the lennard jones fluid
Journal of Chemical Physics, 2006Co-Authors: Rozita Laghaei, Afshin Eskandari Nasrabad, Byung Chan EuAbstract:In the previous papers applying the generic van der Waals equation of state the mean excluded Volume was defined with the contact diameter of particles at which the potential energy is equal to zero—the size parameter in the case of the Lennard-Jones potential. This parameter appears as the upper limit of the integral for the generic van der Waals parameter B (mean excluded Volume divided by the density) in the generic van der Waals equation of state. Since the choice is not unique, in this paper we reexamine the manner of defining the upper limit and propose another choice for the upper limit. We also propose an interpretation of the Free Volume overlap factor α appearing in the Free Volume Theory of diffusion and a method of estimating it in terms of the intermolecular potential energy only. It is shown that with the so-estimated Free Volume overlap factor and the new choice of the upper limit of the integral for B the self-diffusion coefficient in the modified Free Volume Theory of diffusion not only a...
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generic van der waals equation of state modified Free Volume Theory of diffusion and viscosity of simple liquids
Journal of Physical Chemistry B, 2005Co-Authors: Rozita Laghaei, And Afshin Eskandari Nasrabad, Byung Chan EuAbstract:The shear viscosity formula derived by the density fluctuation Theory in previous papers is computed for argon, krypton, and methane by using the self-diffusion coefficients derived in the modified Free Volume Theory with the help of the generic van der Waals equation of state. In the temperature regime near or above the critical temperature, the density dependence of the shear viscosity can be accounted for by ab initio calculations with the self-diffusion coefficients provided by the modified Free Volume Theory if the minimum (critical) Free Volume is set equal to the molecular Volume and the Volume overlap parameter (α) is taken about unity in the expression for the self-diffusion coefficient. In the subcritical temperature regime, if the density fluctuation range parameter is chosen appropriately at a temperature, then the resulting expression for the shear viscosity can well account for its density and temperature dependence over the ranges of density and temperature experimentally studied. In the se...
Alireza Shariati - One of the best experts on this subject based on the ideXlab platform.
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a general viscosity model for deep eutectic solvents the Free Volume Theory coupled with association equations of state
Fluid Phase Equilibria, 2017Co-Authors: Reza Haghbakhsh, Khalil Parvaneh, Sona Raeissi, Alireza ShariatiAbstract:Abstract Deep eutectic solvents (DESs) make up a most-recent category of ‘green’ solvents with a potentially promising future. Insignificant vapor pressure, biodegradability, low cost, task-specific engineering, and high absorption for gases such as CO2 are the most important characteristics of most DESs. To apply DESs in various industries, knowledge of their physical properties is vital. Since the viscosity of a DES is a strong function of temperature, as well as the ratio of the hydrogen bond donating and accepting components, to estimate the viscosity behavior, a model based on sound Theory is proposed in this study, i.e., the Free Volume Theory. Since DESs are strongly associating components, this Theory is enriched by using associating equations of state, namely CPA and PC-SAFT. In this study, a large density and viscosity databank of 27 DESs of different nature, also with varying molar ratios of the hydrogen bond donor and acceptor, were used to propose the model. In this way, a global model is presented for the first time to estimate the viscosities of DESs. The pseudo-component approach, with a 2B association scheme, was considered for the DESs. Both the CPA and the PC-SAFT EoSs, coupled with the Free Volume Theory, showed reliable results, with average AARD% values in viscosity for all of the investigated DESs equal to 2.7% and 2.7%, respectively. Furthermore, both models reliably showed the trend of nearly logarithmic increase in DES viscosity with decreasing temperature. Also, both models accurately estimated the viscosity behavior of the DESs by not only changing the molecular nature of the hydrogen bond donor with a fixed hydrogen bond acceptor, but also at all of the various molar ratios investigated.
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viscosities of pure ionic liquids using combinations of Free Volume Theory or friction Theory with the cubic the cubic plus association and the perturbed chain statistical associating fluid Theory equations of state at high pressures
Industrial & Engineering Chemistry Research, 2017Co-Authors: Reza Haghbakhsh, Khalil Parvaneh, Alireza ShariatiAbstract:In this study, the behaviors of viscosities of nine ionic liquids (ILs) over wide ranges of pressures and temperatures were determined. The investigated ILs belonged to the three imidazolium-based families of tetrafluoroborate, hexafluorophosphate, and bis[(trifluoromethyl)sulfonyl]imide. The two well-known cubic equations of state (EoS’s) of Peng–Robinson (PR) and the Soave–Redlich–Kwong (SRK), as well as the two more-sophisticated EoS’s of cubic plus association (CPA), and perturbed-chain statistical associating fluid Theory (PC-SAFT), were each coupled with two well-known theoretical viscosity models, namely the friction Theory and the Free Volume Theory. Calculated results showed that the Free Volume model, coupled with PC-SAFT, has superior results in comparison to the Free Volume model with the CPA EoS. For the viscosity model of Free Volume, the studied cubic EoS’s did not give accurate results. When the friction model was used, the PC-SAFT EoS once more showed better accuracy than the CPA EoS; how...
Afshin Eskandari Nasrabad - One of the best experts on this subject based on the ideXlab platform.
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Self-diffusion coefficient of two-center Lennard-Jones fluids: Molecular simulations and Free Volume Theory
Journal of Chemical Physics, 2009Co-Authors: Afshin Eskandari NasrabadAbstract:A comprehensive investigation is conducted to study the thermodynamics, structure, and mean Free Volume of rigid two-center Lennard-Jones fluids through Monte Carlo simulations. For a large number of states, the self-diffusion coefficient is computed using the following two different approaches: the equilibrium molecular dynamics simulation method and the modified Cohen–Turnbull Theory. The effects of the bond elongation on different thermophysical properties are studied. The generic van der Waals Theory, which has recently been extended to rigid polyatomic fluids [A. Eskandari Nasrabad and R. Laghaei, J. Chem. Phys.125, 154505 (2006)], is used to compute the mean Free Volume needed in the modified Cohen–Turnbull Theory. The effective site diameter is computed using the virial minimization method and the results are applied within the generic van der Waals Theory. The Gibbs ensemble Monte Carlo simulation technique is applied to determine the location of the fluid phase envelope. The N V T Monte Carlo simulation method is then utilized to compute the equation of state and the correlation functions appearing in the generic van der Waals Theory. It appears that the logarithm of the mean Free Volume versus density is almost linear at ρ > ρ c independent of the bond length, which suggests a universal behavior. The self diffusion coefficient results of the modified Cohen–Turnbull Theory are analyzed in detail.
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transport properties of mie 14 7 fluids molecular dynamics simulation and Theory
Journal of Chemical Physics, 2008Co-Authors: Afshin Eskandari Nasrabad, Nader Mansoori Oghaz, Behzad HaghighiAbstract:An extensive computer simulation study is presented for the self-diffusion coefficient, the shear viscosity, and the thermal conductivity of Mie(14,7) fluids. The time-correlation function formalism of Green–Kubo is utilized in conjunction with molecular dynamics (MD) simulations. In addition to molecular simulations, the results of a recent study [A. Eskandari Nasrabad, J. Chem. Phys. 128, 154514 (2008)] for the mean Free Volume are applied to calculate the self-diffusion coefficients within a Free Volume Theory framework. A detailed comparison between the MD simulation and Free Volume Theory results for the diffusion coefficient is given. The density fluctuation Theory of shear viscosity is used to compute the shear viscosity and the results are compared to those from MD simulations. The density and temperature dependences of different time-correlation functions and transport coefficients are studied and discussed.
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excluded Volume in the generic van der waals equation of state and the self diffusion coefficient of the lennard jones fluid
Journal of Chemical Physics, 2006Co-Authors: Rozita Laghaei, Afshin Eskandari Nasrabad, Byung Chan EuAbstract:In the previous papers applying the generic van der Waals equation of state the mean excluded Volume was defined with the contact diameter of particles at which the potential energy is equal to zero—the size parameter in the case of the Lennard-Jones potential. This parameter appears as the upper limit of the integral for the generic van der Waals parameter B (mean excluded Volume divided by the density) in the generic van der Waals equation of state. Since the choice is not unique, in this paper we reexamine the manner of defining the upper limit and propose another choice for the upper limit. We also propose an interpretation of the Free Volume overlap factor α appearing in the Free Volume Theory of diffusion and a method of estimating it in terms of the intermolecular potential energy only. It is shown that with the so-estimated Free Volume overlap factor and the new choice of the upper limit of the integral for B the self-diffusion coefficient in the modified Free Volume Theory of diffusion not only a...
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modified Free Volume Theory of self diffusion and molecular Theory of shear viscosity of liquid carbon dioxide
Journal of Physical Chemistry B, 2005Co-Authors: Afshin Eskandari Nasrabad, Rozita LaghaeiAbstract:In previous work on the density fluctuation Theory of transport coefficients of liquids, it was necessary to use empirical self-diffusion coefficients to calculate the transport coefficients (e.g., shear viscosity of carbon dioxide). In this work, the necessity of empirical input of the self-diffusion coefficients in the calculation of shear viscosity is removed, and the Theory is thus made a self-contained molecular Theory of transport coefficients of liquids, albeit it contains an empirical parameter in the subcritical regime. The required self-diffusion coefficients of liquid carbon dioxide are calculated by using the modified Free Volume Theory for which the generic van der Waals equation of state and Monte Carlo simulations are combined to accurately compute the mean Free Volume by means of statistical mechanics. They have been computed as a function of density along four different isotherms and isobars. A Lennard-Jones site-site interaction potential was used to model the molecular carbon dioxide interaction. The density and temperature dependence of the theoretical self-diffusion coefficients are shown to be in excellent agreement with experimental data when the minimum critical Free Volume is identified with the molecular Volume. The self-diffusion coefficients thus computed are then used to compute the density and temperature dependence of the shear viscosity of liquid carbon dioxide by employing the density fluctuation Theory formula for shear viscosity as reported in an earlier paper (J. Chem. Phys. 2000, 112, 7118). The theoretical shear viscosity is shown to be robust and yields excellent density and temperature dependence for carbon dioxide. The pair correlation function appearing in the Theory has been computed by Monte Carlo simulations.
