Comparison of different alpha functions, α(Tr), applied in the prediction of supercritical properties of different polar and nonpolar fluids at Boyle temperature

Abstract

The Boyle temperature is the temperature at which the second virial coefficient becomes zero. In this work, capability of different alpha functions, α(Tr), in prediction of supercritical properties of different polar and nonpolar fluids at Boyle temperature is investigated. In this direction, eight different alpha functions, α(Tr), including Peng – Robinson original form (1976), Coquelet et al. (2004), Haghtalab et al. (2011), Saffari – Zahedi (2013), Soave – Redlich – Kwong original form (1972), Ozokwelu – Erbar (1987), Soave (1993) and Nasrifar – Bolland (2004) are coupled with different cubic equations of states including Peng – Robinson (PR), Soave – Redlich – Kwong (SRK), volume – translated Peng – Robinson (VTPR), volume translated Soave Redlich-Kwong (VTSRK) and Patel ‒ Teja ‒ Valderrama (PTV). The obtained results have been compared with the most popular relations, such as Tsonopoulos and Meng – Duan correlations. To understand better, the second virial coefficient and Zeno line have been also depicted and compared with the available experimental data. In addition, the residual properties (HR, SR, UR, and GR) and the second order thermodynamic derivatives (Cp, Cv, us, μJT) at the Boyle condition have been also investigated. Furthermore, the trend of the inversion temperature (Tinv) versus the Boyle temperature is studied for n-alkanes, n-alkenes, amines and noble gases.