Table 3 Semi-empirical models.

Chrastil⁴⁸

\(\mathrm{ln}{S}_{i}={a}_{0}\mathrm{ln}{\rho }_{{\mathrm{CO}}_{2}}+\frac{{a}_{1}}{T}+{a}_{2}\)

MST⁴⁷

\(T\mathrm{ln}\left({y}_{i}\mathrm{P}\right)={a}_{0}+{a}_{1}{\rho }_{{\mathrm{CO}}_{2}}+{a}_{2}T\)

K-J⁷³

\(\mathrm{ln}{y}_{i}={a}_{0}+{a}_{1}{\rho }_{{\mathrm{CO}}_{2}}+\frac{{a}_{2}}{T}\)

Bartle⁴⁹

\(\mathrm{ln}\left({y}_{i}P/{P}_{\mathrm{ref}}\right)={a}_{0}+{a}_{1}({\rho }_{{\mathrm{CO}}_{2}}-{\rho }_{\mathrm{ref}})+\frac{{a}_{2}}{T}\)

Bian⁷⁴

\(\mathrm{ln}{y}_{i}={a}_{0}+\frac{{a}_{1}}{T}+\frac{{a}_{2}\rho }{T}+({a}_{3}+{a}_{4}\rho )\mathrm{ln}\rho\)

Garlapati⁷⁵

\(\mathrm{ln}{y}_{i}={a}_{0}+({a}_{1}+{a}_{2}\rho )\mathrm{ln}\rho +\frac{{a}_{3}}{T}+{a}_{4}\mathrm{ln}(\rho T)\)

Keshmiri⁷⁶

\(\mathrm{ln}{y}_{i}={a}_{0}+\frac{{a}_{1}}{T}+{a}_{2}{P}^{2}+({a}_{3}+\frac{{a}_{4}}{T})\mathrm{ln}\rho\)

Khansary⁷⁷

\(\mathrm{ln}{y}_{i}=\frac{{a}_{0}}{T}+{a}_{1}P+\frac{{a}_{2}{P}^{2}}{T}+\left({a}_{3}+{a}_{4}P\right)\mathrm{ln}\rho\)

Sodeifian¹²

\(\mathrm{ln}{y}_{i}={a}_{0}+{a}_{1}\frac{{P}^{2}}{T}+{a}_{2}\mathrm{ln}\left(\rho T\right)+{a}_{3}\left(\rho \mathrm{ln}\rho \right)+{a}_{4}P\mathrm{ln}T+{a}_{5}\frac{\mathrm{ln}\rho }{T}\)

Belghait³¹

\(\mathrm{ln}{y}_{i}={a}_{0}+{a}_{1}\rho +{a}_{2}{\rho }^{2}+{a}_{3}\rho T+{a}_{4}T+{a}_{5}{T}^{2}+{a}_{6}\mathrm{ln}\rho +\frac{{a}_{7}}{T}\)