Zahra Sharafi - Department of Chemistry, Islamic Azad University, Marvdasht Branch, Marvdasht, Iran Abstract A

A three-parameter cubic equation of state has been proposed for predicting PVT of pure refrigerantssuch as R۲۳۶ea, R۲۳۶fa, R۲۴۵fa, R۲۴۵ca, R۲۱۸, R۲۲۷ea, and R۷۱۷, from freezing point up to critical pointtemperature and pressures up ۶۵۰ atm. We explore the theory of the equation of state from the view pointof Ihm–Song–Mason (ISM) equation of state, which has been derived on the basis of statistical mechanicalperturbation theory, and is characterized by three temperature dependent parameters, a, b, B۲ , and a freeparameter λ. The second virial coefficients are calculated from a correlation based on the heat of vaporization,ΔHvap, and the liquid density at the normal boiling point, ρnb. α(T ) and b(T ) can also be calculated fromsecond virial coefficients by a scaling rule. The theory has considerable predictive power, since it permitsthe construction of the PVT surface from the heat of vaporization and the liquid density at the normal boilingpoint. The results indicate that the liquid densities can be predicted with very good agreement over a widerange of temperatures, ۱۰۰–۴۰۰ K.

Equation of state, correlation, Heat of Vaporization, Saturation Liquid Density of Refrigerants