Page 403 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Properties of Hydrocarbon Mixtures 369

Figure 6-1. Compressibility factor for natural gases [l].

This nonlinear equation can be conveniently solved for y using the simple
Newton-Raphson iterative technique.
Good results give cubic equation of state and its modifications. Most sig-
nificant of the modifications are those of Soave and Peng and Robinson.
The Soave equation (SRK) is
p=-- RT a (6-11)
V-b V(V+b)