An improved parametric crossover model for the thermodynamic properties of fluids in the critical region

Crossover equation of state for the thermodynamic properties of mixtures of methane and ethane in the critical region

“…In Fig. 7 we have plotted Cp and Cv of methane as a function of temperature at p = Pc as calculated from the crossover equation presented in this paper, from the earlier crossover equation of Jin et al [26] and from the crossover equation of Kiselev and Sengers [35]. Our crossover equation and the earlier crossover equation of Jin et al [26] yield essentially identical results.…”

“…Below 175 K there are some systematic deviations for the vapor pressures and liquid densities. An alternative, more phenomenological crossover equation of state for methane and ethane has been proposed by Kiselev and Sengers [35 ]. This alternative crossover equation of state is discussed in Appendix B and its range of validity is comparable to the range of validity, Eq.…”

“…Specifically, we used experimental Cv data obtained by Younglove [32] as corrected by Roder [33], experimental Cv data obtained by Anisimov et al [34] with temperatures shifted by 0.114 K as discussed by Kiselev and Sengers [ 35 ], and experimental speed-of-sound data obtained by Gammon and Douslin [36], by Straty [37], and by Trusler and Zazari [38]. In addition we used Cv values calculated from the global equation [27] [29,30] and by Trappeniers and co-workers [31 ] for methane from values calculated with the crossover equation of state.…”

Thermodynamics of fluid mixtures near to and far from the critical region

“…An equation of state using this approach is typically referred to as a crossover equation of state as described for pure fluids (Chen et al, 1990: Kiselev. 1990; Kiselev et al, 1991;Kiselev and Sengers, 1993;Kiselev and Kostyukova, 1993). This approach has been extended to binary fluid mixtures of type I (Leung and Griffiths, 1973;Jin et al, 1993;Povodyrev et al, 1996;Kiselev, 19971, as well as other types of mixtures (Anisimov et al, 1995a(Anisimov et al, ,b, 1996Cheng et al, 1997).…”

Critical and Crossover Phenomena in Fluids and Fluid Mixtures

“…This approach starts from the asymptotic power-law expansion including the leading correction-to-scaling terms which is then multiplied by an empirical crossover functions so that the equation becomes analytic far away from the critical point. A comparison of this approach with the crossover theory based on a Landau expansion has been discussed in earlier publications [13,78]. One principal difference is that in the application of the results of the RG theory to the Landau expansion the leading correction to asymptotic scaling law is incorporated in the crossover function and recovered upon expanding the crossover function [18].…”