Development of a peng-robinson plus association equation of state for hydrofluorocarbons and their mixtures.

The objective of this work is to develop an equation of state for hydrofluorocarbons based on the Peng-Robinson equation complemented with the association term from the SaFT equation of state. The rationale for this approach is that, on the one hand, hydrofluorocarbons are associating fluids and, on the other hand, using the Peng-Robinson (PR) intends to improve the accuracy of equations based on the Cubic plus association (CPa) scheme. Traditionally, the CPa equations use the Soave-Reclich-Kwong (SRK) equation but the PR equation clearly superseded the SRK, therefore, the expectation is that a CPa equation with the PR would be more accurate that one based on the SRK. Thus, the purpose of this work is to apply the new CPa equation to the calculation of thermodynamic properties of the four hydrofluorocarbons of greatest industrial interest, i.e. HFC-125, HFC-134a, HFC-143a, and HFC-152a, and to mixtures of those compounds. The thermodynamic properties of interest are: pT, vapour pressures, orthobaric densities, isochoric and isobaric heat capacities, and speeds of sound.