A five-parameter cubic equation of state for pure fluids and mixtures

Abstract

A five parameter cubic equation of state, named 5PGDN is presented for the prediction of thermodynamic properties of pure fluids and mixtures. A new alpha function is proposed with two compound specific parameters which are estimated by matching experimental saturation vapor pressure data at two fixed temperatures Tr=0.5,0.7. We have cast three of the five parameters in terms of the remaining two parameters. The 5PGDN uses the critical temperature, the critical pressure, the critical compressibility factor, and two parameters of the alpha function to calculate thermodynamic properties such as saturated vapor pressure, liquid and vapor density, enthalpy of vaporization, sound velocity, heat capacity at constant pressure and volume. The 5PGDN is further used for the prediction of bubble point pressure and vapor mole fraction of several binary mixtures. The accuracy of 5PGDN is demonstrated by comparing results with the Patel-Teja (PT), Haghtalab-Kamali-Mazloumi-Mahmoodi (HKM1) and Ghoderao-Dalvi-Narayan (4PGDN1) equations of state.