Comparison of SAFT-VR-Mie and CP-PC-SAFT in Estimating the Phase Behavior of Acetone + n-Alkane Systems

This study compares the predictions of CP-PC-SAFT and SAFT-VR-Mie for the binary systems of acetone with n-alkanes and some nonassociative gases. CP-PC-SAFT was attached by the 1A association term. SAFT-VR-Mie was examined in three versions: two with just the 1A and 2B association schemes and the third one with the dipolar term only. For each model, a universal non-zero value of k12 was fitted to the upper critical solution temperature (UCST) of an n-pentane (1) + acetone (2) system. The resulting values were applied for predicting the rest of the available data, including liquid-liquid equilibria (LLE) and vapor-liquid equilibria (VLE) from nonassociative gases till n-hexadecane, the critical loci, and the single-phase thermodynamic properties in a wide range of conditions. It was found that thanks to the rigorous obeying of the pure compounds' Tc and Pc, CP-PC-SAFT accurately predicts the VL critical loci, phase equilibria in the systems of nonassociating gases and exhibits clear superiority in simultaneous estimation of VLE and LLE. Besides that, it predicts more accurately the excess enthalpies and sound velocities. Despite the differences between molecular backgrounds of the considered SAFT-VR-Mie versions, their overall performances are rather similar. All of them exhibit poor accuracy in predicting the critical loci, and their capability of simultaneous estimation of VLE and LLE is inferior. However, these approaches are advantageous in the cases of low-pressure VLE from n-pentane till n-nonane and the available isobaric heat capacity data.