Thermodynamic properties ofHe−H2fluid mixtures over a wide range of temperatures and pressures

Abstract

The effect of pressure P and temperature T on the properties of mixing of helium-hydrogen (He-H2 ) fluid mixture is studied based on statistical mechanical perturbation theory. The constituent species are considered to be interacting via a pair potential consisting of short range repulsion and a long range attraction which has been included through a double Yukawa (DY) potential. He and H2 are the lightest elements; therefore, the quantum effect is included via first-order quantum correction in the framework of Wigner-Kirkwood expansion. The dimerization of the H2 molecule is treated as a hard convex body fluid for which the equation of state (EOS) can be derived from hard sphere system based on scaled particle theory. An advanced and most recent EOS has been used for our investigation. The use of the DY potential, which can readily be simulated to empirical potentials, has enabled us to obtain analytical expressions for attractive and quantum energy contributions in terms of Laplace transforms. With a view to ensure internal consistency of the various thermodynamic functions to extract information on segregation and order in the mixture, different functions, such as compressibility factor, Gibbs free energy of mixing, entropy of mixing, and concentration fluctuations in the long wavelength limit, have been calculated as functions of composition of the mixture over an extended region of P and T. The results suggest that segregation, heterocoordination, or both may occur in the He-H2 mixture depending upon its composition, pressure, and temperature.

Equation of State of He-H2 and He-D2 Dense Fluid Mixtures at High Pressures and Temperatures

“…But the rotational and vibrational temperatures for H 2 and D 2 molecules are different, T r = 85 K and T v = 6210 K for H 2 . Figure 3 shows a comparison of isotherms of fluid helium and hydrogen with the Monto-Carlo (MC) simulations [13], calculations of Ali et al [10], and the effective one-component model [12]. The present results are in agreement with the MC data and the effective onecomponent model.…”

“…Recently, Ali et al [10] have studied the effect of pressure and temperature on the properties of mixing of helium-hydrogen fluid mixtures based on statistical perturbation theory. The constituent species are considered to be interacting by a pair potential consisting of a short-range repulsion and a long-range attraction which is included through a double Yukawa (DY) potential.…”

Theoretical and analytical Radial Distribution Function for non-polar mixtures

“…Tables 1 and 2, the quantum corrections to pressure P and internal energy U were not included in MC simulation results [1]. As shown in Table 1, our method gives agreeable results with that of MC simulations [1] and Yukawa-type EOS [2] over a very wide range of conditions. Some results by this RDF overestimate for about 15%-25% when comparing the previous work [1,2], but are much better than that of Ref.…”

“…In order to examine the accuracy and reliability of this model, the Double Yukawa (DY) potential of H 2 -H e fluid mixture [2] was used and the quantum effect via a first-order quantum correction in the Wigner-Kirkwood expansion [19,20] was taken into account.…”

“…The mean total potential energy of N molecules U 2 The mean total pair-wise potential energy of the system u ij (r)…”