The Abdoul-Rauzy-Peneloux Group Contribution Equation of State Extended to CFC-Containing Mixtures

Artikel i vetenskaplig tidskrift, 1993

This study contributes to the development of new thermodynamic models, useful for the prediction of refrigerant-mixture properties. Mixtures are considered to be potential substitutes for the environmentally harmful chlorofluorocarbons. Here the Abdoul—Rauzy—Pénéloux (ARP) equation of state (EOs) is used, which combines a group contribution excess Helmholz energy model with traditional cubic EOSs. This EOS, initially developed for different petroleum mixtures, has been extended to cover also certain compounds containing chlorine and fluorine. A predictive method for PVT modelling of mixtures containing CFCs, HCFCs, HFCs, FCs and hydrocarbons has thus been developed. From experimental data for 31 different binary systems, 19 general group parameters were estimated. the error on the calculated vapor pressure for these systems does not exceed 5.1% for any of the considered mixtures. This demonstrates the effectiveness of the method since the traditional mixing rules would have demanded 31 specific interaction parameters to describe the same number of systems, without the possibility of extending their validity to other mixtures. In order to verify the predicting capacity of the method, it has also been applied to a ternary and an azeotropic system, that have not been included in the estimation procedure of the parameters. The results from these applications are deviations on the calculated pressure of 0.7 and 26% for the ternary and the azeotropic system, respectively.