Equations for the Curl-Pitzer method

The reduced temperature (Tr) and reduced pressure (Pr) are the ratios of the temperature and pressure to the critical temperature(Tc) and critical pressure (Pc), respectively:

The following equation gives the compressibility factor of a fluid that uses the Curl-Pitzer equation of state:

where

w is the acentric factor of the fluid under consideration

Zs is the compressibility factor of the simple fluid

Zl is the deviation of the compressibility factor of the real fluid from the simple fluid