Development of the translated-consistent tc-PR and tc-RK cubic equations of state for a safe and accurate prediction of volumetric, energetic and saturation properties of pure compounds in the sub- and super-critical domains

- Translated and consistent versions of the PR and RK cubic EoS are developed.
- tc-PR is certainly the safest and the most accurate cubic EoS ever published.
- Average deviations on vapor pressures are lower than 1%.
- Average deviations on enthalpies and heat capacities are about 2%.
- Average deviations on saturated liquid volumes are about 2.3%.

In this paper, translated and consistent versions of the Peng-Robinson (tc-PR) and Redlich-Kwong (tc-RK) cubic equations of state (CEoS) are developed. The adjective consistent means that the α-function used in such models passes the consistency test we recently developed and which guarantees safe extrapolation in the supercritical region and safe VLE calculation in multi-component systems. The adjective translated means that a volume translation aimed at exactly reproducing the experimental saturated liquid volume at a reduced temperature of 0.8 was used. The key conclusion of this paper is that the tc-PR EoS is certainly the safest and the most accurate 3-parameter cubic EoS ever published. Indeed the average deviations over roughly 1000 compounds belonging to different chemical families are: ΔPsat<1 %, ΔvapH=ΔcP,Lsat=2% and ΔvLsat(Tr<0.9)=2.3%.In the case of a lack of experimental data to fit the 3 parameters of the α-function and to determine the value of the volume correction, the second part of this study aims at providing a generalized version of the tc-PR and tc-RK CEoS in which all parameters can be estimated from the mere knowledge of the acentric factor.

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