Using Lee-Kesler equation of state to compute the compressibility factor of CO2-content natural gas

To improve the compressibility factor prediction of CO2-content natural gas, this short communication proposes a new combinational Stewart-Burkhardt-Voo (SBV) + Prausnitz-Gunn (PG) mixing rule for the Lee-Kesler equation of state. The rule suggests using SBV and PG mixing rules for the pseudocritical temperature and pressure computations, respectively, when the reduced temperature is higher than one and the reduced pressure is higher than five; otherwise, the pseudocritical temperature and pressure is calculated according to SBV mixing rule. Comparisons between experimental and calculation data show that the maximum average relative deviation is 1.56% when the mole fraction of CO2 is less than 50%.