Lennard-Jones equation of state

Johnson, Zollweg and Gubbins

Johnson, Zollweg and Gubbins ^[1] proposed an equation of state based on 33 parameters within a modified Benedict, Webb and Rubin equation of state, which accurately reproduces the vapour-liquid equilibrium curve.

The Kolafa and Nezbeda equation of state ^[2] provides us with the Helmholtz energy function: (Eq. 30):

A=A_{\mathrm {HS} }+\exp(-\gamma \rho ^{2})\rho T\Delta B_{2,{\mathrm {hBH} }}+\sum _{ij}C_{ij}T^{i/2}\rho ^{j}

z\equiv {\frac {P}{\rho T}}=z_{\mathrm {HS} }+\rho (1-2\gamma \rho ^{2})\exp(-\gamma \rho ^{2})\Delta B_{2,{\mathrm {hBH} }}+\sum _{ij}jC_{ij}T^{i/2-1}\rho ^{j}

and the internal energy (Eq. 32)

U={3(z_{\rm {HS}}-1) \over d_{\rm {hBH}}}\,{\partial d_{\rm {hBH}} \over \partial (1/T)}+\rho \exp(-\gamma \rho ^{2})\,{\partial \Delta B_{\rm {2,hBH}} \over \partial (1/T)}-\sum _{ij}\left({i \over 2}-1\right)C_{ij}\,T^{i/2}\rho ^{j}

The Ree equation of state ^[3] is an extension of the earlier work of Hansen ^[4] in the high temperature region.

Boltachev and Baidakov have paid particular attention to including data from the metastable region ^[5].

The Pieprzyk-Brańka-Maćkowiak and Heyes equation of state ^[6] consists of a parameterisation of the modified Benedict, Webb and Rubin equation of state.

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