Critical scaling laws and a classical equation of state

In this paper we present a method which modifies a classical equation of state by incorporating the nonclassical critical behavior. As an example we have applied our procedure to the Carnahan-Starling-DeSantis (CSD) equation of state. The resulting equation reproduces the universal scaling behavior near the critical point and reduces to the universal ideal-gas behavior at low densities. We show that the renormalized CSD equation yields an improved and consistent representation of both mechanical and caloric thermodynamic properties. In addition, the suppression of the critical temperature due to the critical fluctuations is clearly demonstrated.     

An equation for calculation of the thermal conductivity of gases and liquids

A unified equation is proposed for calculation of the thermal conductivity of gases and liquids. The procedure for formulation of the equation is illustrated in the example of nitrogen.Translated from Inzhenerno-Fizichesii Zhurnal, Vol.20, No. 1, pp. 119–124, January, 1971.     

A three parameter equation of state for gases

This paper presents an equation of state having the following features. It holds for many gases for temperatures from near critical to about five times critical, and for densities from zero to a little above critical, with the exception of the immediate vicinity of the critical point. It also holds for mixtures. Its accuracy is excellent, in most cases within experimental error. Exceptions are H₂O, CO₂, H₂ at high density. In the best cases the rms deviations in the compressibility factor are a few parts in ten thousand. In relatively poor cases the deviations are a few parts per thousand.The equation has a single reduced form for all gases, and requires only three characteristic parameters to identify each gas: a reducing parameter, T_B; a reducing density, d_o; and a dimensionless parameter, k_B. These three parameters are readily (though often not uniquely) evaluated from experimental data. Besides determining the PVT behaviour of a gas, including its virial coefficients, these three parameters are directly related to those in the common three-parameter intermolecular potentials.     

Prediction of transport properties of dense gases and liquids by the Peng-Robinson (PR) equation of state

An attempt is made in this work to combine the Enskog theory of transport properties with the simple cubic Peng-Robinson (PR) equation of state. The PR equation of state provides the density dependence of the equilibrium radial distribution function. A slight empirical modification of the Enskog equation is proposed to improve the accuracy of correlation of thermal conductivity and viscosity coefficient for dense gases and liquids. Extensive comparisons with experimental data of pure fluids are made for a wide range of fluid states with temperatures from 90 to 500 K and pressures from 1 to 740 atm. The total average absolute deviations are 2.67% and 2.02% for viscosity and thermal conductivity predictions, respectively. The proposed procedure for predicting viscosity and thermal conductivity is simple and straightforward. It requires only critical parameters and acentric factors for the fluids.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Generalization of the classical Rayleigh equation to several non-Newtonian liquids

Equations are derived that describe the change in the radius of a spherical gas inclusion in the Bingham, Ellis, Reiner-Rivlin, Shul'man, Kapur-Gupta,and Oswald de Vielle non-Newtonian liquids, as well as in a power-law liquid.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 4, pp. 677–680, October, 1978.     

Virial equation of state of nonpolar gases

An equation of state is studied in which the second and third virial coefficients are calculated theoretically and an empirical expression is used for the fourth virial coefficient. It is shown that this equation of state describes the experimental data on the compressibility of nonpolar gases for T 0.7T_B and 0.8p_cr.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 47, No. 1, pp. 108–111, July, 1984.     

Theory of equation of state for real gases 1.

An equation of state for real gases is derived by using correlation relations between the components of the thermal velocity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 3, pp. 519–528, March, 1978.     

Correlation between the equations of transfer coefficients and the equation of state for liquids

On the basis of test data on p, v, T, thermal conductivity, and dynamic viscosity of toluene and water, it is shown that the equations of transfer coefficients can be represented in a form analogous to the equation of state.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 3, pp. 492–497, September, 1972.     

Generalized form of the equation of state of real gases

A simple and reliable equation of state is proposed on the basis of an analysis of the geometric structure of the thermodynamic surface. A three-parameter procedure for generalizing the properties of a wide range of nonpolar gases is validated.Trnaslated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 4, pp. 699–704, October, 1979.     

Modification of the cell model and the equation of state of liquids

Using an effective intermolecular potential and a modification of the cell model, we obtain the equation of state for liquids. The parameters of the equation of state are calculated for 60 different materials.Translated from Inzherno-Fizicheskii Zhurnal, Vol. 54, No. 1, pp. 65–72, January, 1988.     

The covolume and equation of state of high-temperature real gases

It is shown that the equation of state of a real gas can be described under certain conditions in terms of the covolume.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 2, pp. 273–275, August, 1986.     

Compressibility charts for gases with different acentric factors and evaluation of the Redlich-Kwong-Soave equation of state

The Redlich-Kwong-Soave generalized equation of state is transformed into a dimensionless form, which permits plotting of one compressibility chart for each value of the acentric factor ω. Such charts are provided for various values of ω in the range ω=0–0.6. A systematic evaluation of the Redlich-Kwong-Soave equation is made by comparison with the latest version of the generalized compressibility chart given by Nelson and Obert. It is found that for ω=0, the Redlich-Kwong-Soave compressibility chart agrees well with the Nelson-Obert chart, apart from a small region near the critical point: For values of the reduced pressure p_r<1, the relative ercompressibility factor z is less than about 1%. For reduced pressures and temperatures in the ranges 1≤p_r≤8 and 1≤T_r≤3.5, respectively, it is found e≤1% at the higher values of T_r, e≤5% at the intermediate T_r and e≤10% at the lower T_r. The highest disagreement is observed near the critical point (p_r=T_r=1). Moreover, the exact compressibility chart of the real air is developed, based on its exact equation of state, and compared with the Redlich-Kwong-Soave compressibility chart for ω=0.     

The equation of state for a mixture of nonpolar gases at moderate densities

The virial equation of state for the (12-7, ) pair model potential is extended to mixtures of nonpolar gases. The applicability of the equation is examined, and it is shown that calculations agree with experiment within the error of the measurements.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 48, No. 1, pp. 114–118, January, 1985.     

On the theory of the equation of state of real gases. II

A comparison is made between the equation of state derived earlier and experiment.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 4, pp. 690–696, April, 1978.     

General equations for the caloric functions of gases and liquids

A generalized thermal equation of state is used in deriving equations for the major caloric functions of gases and liquids.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 3, pp. 520–530, September, 1978.