Crossover EOS versus classical EOS for pure fluids

Kudelkova, Lucie; Lovland, Jorgen; Voňka, Petr

doi:10.1016/j.fluid.2003.08.006

Cited by 14 publications

(10 citation statements)

References 69 publications

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“…Equation of state (EOS) is of crucial importance to predict or correlate fluid thermodynamic properties [1,2,3]. Since van der Waals proposed the first version of his EOS [4], many modifications have been proposed, and today, there are numerous more accurate EOSs reported in the literature for describing the behavior of simple fluids and fluid mixtures.…”

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confidence: 99%

New criteria for the equation of state development: Simple model fluids

Duda¹,

Orea²

2008

Fluid Phase Equilibria

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Recently we have proposed (J. Chem. Phys. 128 (2008) 134508) a new rescaling of fluid density ρ by its critical value ρ 2/3 c to apply the corresponding states law for the attractive Yukawa fluids study. Analysis of precise simulation results allows us to generalize this concept to the case of simple fluids with different interparticle interactions, like Mie (n,m) and Sutherland pair potentials. It is shown, that there is a linear relationship between the critical pressure and critical temperature, as well as the critical density and inverse critical temperature for these frequently used pair potentials. As a consequence, the critical compressibility factor of these model fluids is close to its universal value measured experimentally for different real substances. PACS numbers:Equation of state (EOS) is of crucial importance to predict or correlate fluid thermodynamic properties [1,2,3]. Since van der Waals proposed the first version of his EOS [4], many modifications have been proposed, and today, there are numerous more accurate EOSs reported in the literature for describing the behavior of simple fluids and fluid mixtures. An improvement in the accuracy of analytical EOSs for the modeling of experimental data of real fluids is usually achieved, not by improving theoretical base, but by introducing empirical temperature functionalities in their parameters. Obviously, such empirical or semi-empirical approaches, beside to require a lot of experimental [1,2] or simulation data [5,6], forbidden molecular interpretation of results. On the other hand, theoretically based EOSs are very general and applicable for the entire family of systems obeying the given interparticle potential model [7,8,9,10,11,12,13,14,15,16].The most apparent progress toward EOS was made by applying principles of statistical mechanics. Integral equation [10,11], thermodynamic perturbation [9,12,13,14,15,16], and mean field theories [17] are the most common theoretical approaches to develop analytical EOS for simple fluids. The advantage of theoretically based EOS over their empirical counterparts is that they can be further improved by testing against computer simulations and later be used as a reference for perturbation theory calculations of bulk and interfacial properties of more complex fluids such as polymers and associating systems (i.e., hydrogen-bonding fluids) [18,19,20,21,22,23].Although last decades significant progress has been achieved in the development of theoretically based expressions for EOS, there is still a lack of equations that described PVT properties of simple fluids in wide range of thermodynamic parameters. Such precise analytical expression may be obtained if one has a set of universal criteria (as for example, corresponding states law [24,25,26]) or/and apply self-consistent integral equations [27].Recently, we have applied the corresponding states law for the hard core attractive Yukawa (HAY) fluid [26], and revealed that after a certain rescaling of fluid number density ρ the reduced surface tension and pressur...

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confidence: 99%

New criteria for the equation of state development: Simple model fluids

Duda¹,

Orea²

2008

Fluid Phase Equilibria

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“…There are also severe numerical complexities in the neighborhood of mixture critical points and critical end points. All of these are areas of active research [158][159][160][161][162][163][164][165][166][167][168][169][170].…”

Section: Fugacity Coefficientmentioning

confidence: 99%

Solubilities in supercritical fluids

Knox

2005

Pure and Applied Chemistry

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Solubilities in supercritical fluids are of great importance in a wide variety of applications. These applications include: production of controlled drug delivery systems, powder processing, pollution prevention and remediation, methods for spraying paints and coatings, precipitation/crystallization processes, bioseparations, and food processing. Examples of some of these applications will be given.Supercritical fluid processes make use of the significant variation of solubility with pressure when the solvent is a supercritical fluid. This permits the accomplishment of many processes that would be otherwise very difficult to achieve. To fully understand the benefits of such processes, one must understand the phase behavior of such systems. The types of phase behavior that can be observed will be discussed, along with the ways that this behavior can be used to modify solubilities in such fluids.There have been many methods proposed for the experimental determination of solubilities in supercritical fluids. These will be reviewed in general, and recommendations for preferred methods given.Solubilities in supercritical fluids can be correlated and predicted by making use of thermodynamic calculations involving equations of state, as well as by other methods. The various methods will be reviewed, and recommendations given for various applications.

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“…Another alternative is the use of specific coefficients for each fluid in a general cubic equation of state [11,12]. Also, some crossover equations of state have been proposed based on the simplest classical cases such as the wellknown van der Waals equation [13,14]. Due to the complexity of the required calculations, the use of accurate empirical correlations giving the saturated liquid density is frequently preferred [1,4,6,[15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…There are a few very simple EOSs such as the van der Waals, the Redlich-Kwong [20], and the Fox [21], which can be considered as predictive since they contain only two fixed parameters that are calculated by knowing only the critical properties. They are, in general, not accurate but have served as the basis for the development of more complex empirical equations [8,[11][12][13][14]19]. These empirical EOSs usually give a better description of the fluid properties, but they have the disadvantage of containing a certain number of adjustable parameters.…”

Section: Introductionmentioning

confidence: 99%

Liquid Saturation Density from Simple Equations of State

Mulero

Cachadiña

2007

Int J Thermophys

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Several simple equations of state, requiring only two input properties, have been studied in order to determine the liquid saturation density of 144 fluids of different kinds. This study includes old and new simple modifications of the van der Waals equation of state, and the Carnahan-Starling-YelashKraska and Carnahan-Starling-Dieterici equations. The new simple modifications of the van der Waals equation give better overall results than some other more complex proposed equations, especially near the critical point. The recent equation proposed by Eslami including the boiling temperature and density as input parameters was also checked, and was found not to reproduce the critical point, but to give excellent results at intermediate or low temperatures. As a reference, the behavior of the well-known SoaveRedlich-Kwong and Peng-Robinson equations, and the more recent expression proposed by Mohsen-Nia et al. that requires three input parameters were also checked. The latter does not improve the accuracy of the PengRobinson equation, and very simple van-der-Waals type equations give better overall results.

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Crossover EOS versus classical EOS for pure fluids

Cited by 14 publications

References 69 publications

New criteria for the equation of state development: Simple model fluids

New criteria for the equation of state development: Simple model fluids

Solubilities in supercritical fluids

Liquid Saturation Density from Simple Equations of State

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