说明：  Perform two phase equilibrium calculation with successive substitution method (SSM) for the below five-component system at 390K and selected pressure points (4.42, 5, 5.55 MPa) to determine vapor phase fraction, vapor/liquid phase composition and iteration numbers. Choose either PR or SRK Equation of State (EOS) as the thermodynamic model. C2 C3 nC4 nC5 nC6 zi 0.39842 0.29313 0.20006 0.07143 0.03696