Ali Boushehri

Equilibrium and Transport Properties of Eleven Polyatomic Gases At Low Density

This study presents a computer programmable, thermodynamically consistent representation of the second virial coefficient B, viscosity η, self‐diffusion coefficient D, and isotopic thermal diffusion factor α0 of the eleven gases: N2, O2, NO, CO, N2O, CO2, CH4, CF4, SF6, C2H4, and C2H6, all at low density. Limited thermodynamic consistency is achieved by the use of four scaling parameters (σ, e, V*0, ρ*) in addition to the molecular weight. In terms of these parameters, the collision integrals for the transport properties obey a single law of corresponding states. Furthermore, Ω(2,2)* (T) is the same as that for the universal correlation of the monatomic gases [J. Chem. Phys. Ref. Data 13, 229 (1984)] whereas Ω(1,1)* (T) is only slightly modified. The same parameters nearly correlate the spherical part B0(T)=B(T)−Bns(T) of the second virial coefficient corrected for the most important nonspherical influences; its dimensionless form B*0(T) differs from that for the monatomic gases and also, somewhat, for ea...

Equation of state for compressed liquids and their mixtures from the cohesive energy density

A procedure is presented, based on statistical-mechanical theory, for predicting the equation of state of compressed normal liquids and their mixtures from two scaling constants that are available from measurements at ordinary pressures and temperatures. The theoretical equation of state is that of Ihm, Song, and Mason, and the two constants are the enthalpy of vaporization and the liquid density at the triple point, which are related to the cohesive energy density of regular solution theory. The procedure is tested on a number of substances ranging in complexity from Ar and CO2 to n-heptane and toluene. The results indicate that the liquid density at any pressure and temperature can be predicted within about 5%, over the range from Ttp to Tc and up to the freezing line. Possible methods of determining the scaling constants are discussed, as well as other possible choices for scaling constants.

Equation of state for compressed liquids from surface tension

A method for predicting an analytical equation of state for liquids from the surface tension and the liquid density at the freezing temperature (γ1,ϱ1) as scaling constants is presented. The reference temperature. Tref. is introduced and the product (TrefT11 2) is shown to be an advantageous corresponding temperature for the second virial coeflicienls. B2(T). of spherical and molecular fluids. Thus, B2(T) follows a promising corresponding states principle and then calculations forα(T) andb(T), the two other temperature-dependent constants of the equation of state, are made possible by scaling. As a result, (γ1,ϱ1) are sufficient for the determination of thermophysical properties of fluids from the freezing line up to the critical temperature. The present procedure has the advantage that it can also be used in cases whereTc andPc are not known or the vapor pressure is too small to allow accurate measurements. We applied the procedure to predict the density of Lennard-Jones liquids over an extensive range of temperatures and pressures. The results for liquids with a wide range of acentric factor values are within 5%.

Direct determination of interaction potentials from gas viscosity measurements alone

Abstract The direct inversion scheme of Smith and co-workers has been modified so as to remove the requirement that the well depth ϵ be known independently before the interaction potential can be determined from gas viscosity data. It is shown that the entire potential, including ϵ, can be determined within about 5% even when the viscosity measurements are uncertain by 1%.

On the extended principle of corresponding states and the pair interaction potential

Direct inversion methods are used to analyze the extended principle of corresponding states of Kestin and co-workers in terms of the pair interaction potential. It is shown how reference to the potential makes possible a number of extensions and improvements to the corresponding-states correlations. Specifically, the range of validity of the principle is made more precise, the consistency between gas viscosities and second virial coefficients is checked, and it is shown how to improve the available temperature range over which predictions can be made and the precision with which properties can be predicted.

An analytical equation of state for mercury

This paper presents a procedure for predicting the equation of state of mercury, by including mercury in the scope of a new statistical mechanical equation of state that is known for normal fluids. The scaling constants are the latent heat of vaporization and the density at the melting temperature, which are related to the cohesive energy density. Since experimental data for the second virial coefficient of mercury are scarce, a corresponding-states correlation of normal fluids is used to calculate theB(T) of mercury. The free parameter of the ISM equation, λ, compensates for the uncertainties inB(T). Also, we can predict the values of two temperature-dependent parameters, α(T) andb(T), with satisfactory accuracy from a knowledge of ΔHvap andpm, without knowing any details of the intermolecular potentials. While the values ofB(T) are scarce for mercury and the vapor pressure of this metal at low temperatures is very small, an equation of state for mercury from two scaling parameters (ΔHvap,pm) predicts the density of Hg from the melting point up to 100° above the boiling temperature to within 5%.

Equation of state for molten alkali metal alloys

Calculated results of the liquid density of binary molten alloys of Na–K and K–Cs over the whole range of concentrations and that of a ternary molten eutectic of Na–K–Cs from the freezing point up to several hundred degrees above the boiling point are presented. The calculations were performed with the analytical equation of state proposed by Ihm, Song, and Mason, which is based on statistical-mechanical perturbation theory. The second virial coefficients were calculated from the corresponding-states correlation of Mehdipour and Boushehri. Calculation of the other two temperature-dependent parameters was carried out by scaling. The calculated results cover a much wider range of temperatures and are more accurate than those presented in our previous work.

An analytical equation of state for molten alkali metals

This paper brings the molten alkali metals into the scope of a new statistical mechanical equation of state that is known to satisfy normal fluids over the whole range. As for normal fluids, the latent heat of vaporization and density at freezing temperature are the only inputs (scaling factors). The correspondingstates correlation of normal fluids is used to calculate the second virial coefficient,B2(T), of alkali metals, which is scarce experimentally and its calculation is complicated by dimer formation. Calculations of the other two temperature-dependent constants,α(T) andb(T), follow by scaling. The virial coefficients of alkali metals cannot be expected to obey a law of corresponding states for normal fluids. The fact that two potentials are involved may be the reason for this. Thus, alkali metals have the characteristics of interacting through singlet and triple potentials so that the treatment by a single potential here is fortuitous. The adjustable parameter of the equation of state,γ, compensates for the uncertainties inB2(T). The procedure used to calculate the density of liquids Li through Cs from the freezing line up to several hundred degrees above the boiling temperatures. The results are within 5 %.

On the Equation of State for Quantum Systems

An analytical equation of state (EOS) proposed by Song and Mason was applied to four quantum systems including 4 He, Ne, H 2 , and CH 4 . The best intermolecular pair potentials were taken to evaluate the second virial coefficients. For CH 4 and Ne, the first quantum correction, and for 4 He and H 2 , up to the second quantum correction were performed on the classical second virial coefficients. The calculated second virial coefficients were applied to predict the density of four systems in both subcritical and supercritical regions. Agreement with experiment was excellent for all systems.

Linear Isotherm for Compressed Molten Alkali Metals

Molten alkali metals are shown to be in the domain of the newly developed linear regularity that is valid for pure compressed liquids and liquid mixtures. It holds in the range of melting to boiling temperature and shows deviations as the critical temperature is approached. The agreement with experimental data is better than 1.4% when it is used to predict the density of molten Li, Na, K, Rb, and Cs metals. A reasonable conformity with the ISM statistical mechanical equation of state is manifested.