Prediction of critical points of real fluids using imperfect boson gas model: Perturbed virial expansion

Critical point is one of the most important thermophysical properties of fluids, which has important applications in industry. Perturbed virial expansion (PVE) is a useful tool used to predict the critical points of real fluids. In this paper, the imperfect boson gas model is first considered to study three real fluids such as [Formula: see text]Rb, [Formula: see text]Na and [Formula: see text]Ce. By using this model, the virial coefficients are analytically calculated up to the fourth order. Then, the critical temperature, pressure and density are determined by using the PVE. In this regard, two different reference fluids are employed such as Percus–Yevick (PY) and Carnahan–Starling (CS). The critical points are computed by the PVE up to the second, third and fourth order taking into account two reference fluids. The obtained critical points are also compared with the available data. The results of this model show that the accuracy of the obtained critical points depends on two factors, the used reference fluid and order of virial coefficient. The critical points obtained using the virial expansion up to the fourth order in addition to the second reference fluid (CS) are in good agreement with the available results. Our data indicate that the best predicted critical temperature corresponds to [Formula: see text]Rb and [Formula: see text]Na with a 1% error. Also, the best critical pressure relates to [Formula: see text]Ce with a 1% error. The best critical density corresponds to [Formula: see text]Na with a 1.4% error.