New Publication – A Comprehensive Assessment of COSMO-SAC Models for Predictions of Fluid Phase Equilibria

A Comprehensive Assessment of COSMO-SAC Models for Predictions of Fluid Phase Equilibria

Robin Fingerhuta, Wei-Lin Chenb, Andre Schedemannc, Wilfried Cordesc, Jürgen Rareyc, d, Chieh-Ming Hsiehe, Jadran Vrabeca, * and Shiang-Tai Linb, *

a Thermodynamics and Energy Technology, University of Paderborn, 33098 Paderborn, Germany, *E-Mail:,

b Department of Chemical Engineering, National Taiwan University, 10617 Taipei City, Taiwan, *E-Mail:,

cDDBST GmbH, 26129 Oldenburg, Germany,

d Carl-von Ossietzky University Oldenburg, 26129 Oldenburg, Germany,

eDepartment of Chemical & Materials Engineering, National Central University, 320 Taoyuan City, Taiwan,


ABSTRACT: Two recent and fully open source COSMO-SAC models are assessed for the first time on the basis of very large experimental data sets. The model performance of COSMO-SAC 2010 and COSMO-SAC-dsp (2013) is studied for vapor-liquid equilibrium (VLE) and infinite dilution activity coefficient (𝛾𝛾𝑖𝑖∞) predictions, and it is benchmarked with respect to the group contri-bution models UNIFAC and mod. UNIFAC(DO). For this purpose, binary mixture combinations of 2,295 components are investi-gated. This leads to 10,897 𝛾𝛾𝑖𝑖∞ and 6,940 VLE mixtures, which corresponds to 29,173 𝛾𝛾𝑖𝑖∞ and 139,921 VLE data points. The model performance is analyzed in terms of chemical families. A MATLAB program is provided for the interested reader to study the models in detail. The comprehensive assessment shows that there is a clear improvement from COSMO-SAC 2010 to COSMO-SAC-dsp and from UNIFAC to mod. UNIFAC(DO). The mean absolute deviation of 𝛾𝛾𝑖𝑖∞ predictions is reduced from 95 % to 86 % (COSMO-SAC 2010 to COSMO-SAC-dsp) and from 73 % to 58 % (UNIFAC to mod. UNIFAC(DO)). A combined mean absolute deviation is introduced to study the temperature, pressure and vapor mole fraction errors of VLE predictions, and it is reduced from 4.77 % to 4.63 % (COSMO-SAC 2010 to COSMO-SAC-dsp) and from 4.47 % to 3.51 % (UNIFAC to mod. UNIFAC(DO)). Detailed error analyses show that the accuracy of COSMO-SAC models manly depends on chemical family types, but not on the molecular size asymmetry or polarity. The present results may serve as a reference for the reliability of predictions with COSMO-SAC methods and provide directions for future developments.


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