Abstract:
The predictive ability of CPA, SRK, PR and PR-Sun equation of state (EoS) were evaluated with the vapor pressure, liquid volume and enthalpy of vaporization of 22 associative compounds. The five parameters of CPA EoS were regressed with vapor pressures and liquid densities. CPA-1 was obtained with vapor pressures and CPA-2 was obtained with vapor pressures and liquid densities. The capabilities of CPA-1 and CPA-2 EoS for the prediction of thermodynamic properties of 22 compounds were also evaluated. The results show that CPA-1, CPA-2 and PR-Sun EoS present better results for the prediction of vapor pressures, with average relative deviations (ARD) being 0.46%, 0.45% and 0.45%, respectively, which are better than SRK and PR EoS. The ARD of CPA-2 EoS for the prediction of liquid volume is 1.90%, and the ARD of each substance is less than 1.00% (excluding water). The prediction of liquid volumes of CPA-2 EoS is more accurate than that of the CPA-1 (11.47%), SRK, PR, and PR-Sun EoS. The ARDs of CPA-1 and CPA-2 EoS for the prediction of enthalpy of vaporization are 8.30% and 8.24%, respectively. The results are slightly larger than those predicted with PR-Sun EoS, but are less than those predicted with SRK and PR EoS. The results of CPA EoS for the predictions of thermodynamic properties of associating substances are more accurate than that predicted with the cubic equation of state. The parameters of CPA EoS regressed with vapor pressures and liquid densities are better than that merely regressed with vapor pressures. The CPA has obvious advantage than the cubic equation of state for the predictions of thermodynamic properties. It is worth applying to more mixture systems.