Esmaeilzadeh - Department Of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran
Roshanfekr - Department Of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran

A new three parameter cubic equation of state was developed based on generalize Van der Waals theory [1] and focused on a modification of attractive pressure term of Van der Waals equation. It has one temperature dependent parameter called a(T) and others are constant. The value of a(T) was evaluated by minimizing saturated liquid density deviation from experimental value and satisfying the vapor liquid equilibrium condition simultaneously. Then a(T) was fitted against reduced temperature, experimental compressibility factor and Pitzer acentric factor. The new equation has advantages of both accuracy and simplicity. The results of calculation from the new equation of state show a better prediction of saturated liquid density and vapor pressure to some other equations of state such as Peng Robinson and Patel Teja, especially in near critical region.

Equation of State, VLE, Saturated Liquid Density, Peng Robinson, Patel Teja