Peng–Robinson

Developed from the Redlich–Kwong–Soave EOS, this EOS [1] gives better vapour pressure and density results for many petrochemical compounds. For this class of compounds even caloric data are represented rather well.

For heavy alkanes an update of this EOS is available, referred to as PR78 on this website [2].

The critical compression factor of this EOS is fixed. It is not possible for this EOS to match all 3 critical conditions.

adjustable parameters: 3

For mixture calculations the following mixing theories are available:

- 1FS: the authors' original mixing theory, which is a Soave-style 1-fluid mixing theory [1]
- 1FSa: modified version using averaged acentric factors, often better than 1FS at high pressures
- 1F: van der Waals 1-fluid mixing theory
- m1Fns: modified 1-fluid theory for nonspherical molecules, a simplified version of D1/m1Fdns (without the density-dependent fractal exponent)
- PPR78: predictive PR78 (for the PR78 variant only), similar to 1FS, but with a group contributions-based method for the estimation of binary interaction parameters [3]. The original table of group contributions of that publication has been replaced with an extended version (“E-PPR78”) [4].

[1] D. Y. Peng and D. B. Robinson, *Ind. Eng. Chem. Fundam.* 15
(1976) 59–64.

[2] D. B. Robinson and D. Y. Peng, *GPA Research Report* RR-28
(1978), 1–36.

[3] J.-W. Qian, R. Privat, and J.-N. Jaubert, *Ind. Eng. Chem. Res.* 52
(2013) 16457–16490.

[3] J.-W. Qian, R. Privat, J.-N. Jaubert, C. Coquelet, Ramjugernath, D..
*Int. J. Refrig.* 73 (2017), 65–90.

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