271171 Comparison of Vapor-Liquid and Liquid-Liquid Equilibrium Prediction From Combination of PRSV and Cosmosac Through Different Mixing Rules

Monday, October 29, 2012
Hall B (Convention Center )
Chieh-Ming Hsieh and Shiang-Tai Lin, Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan

The fluid phase equilibrium behaviors of chemicals are important in the design, development, optimization, and control of chemical processes. In our previous study, a new revision of the COSMO-SAC model is proposed to provide better accuracy in predictions of both vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE). However, the COSMO-SAC model, an excess Gibbs energy (Gex) model, is not sufficient to directly apply to describe pressure and volume effects of fluid phase equilibrium. A simple way is to combine the COMO-SAC model and PRSV equation of state (EOS) through a Gex-based mixing rule. In this study, the performance of previously published mixing rules, such as MHV1 and WS mixing rule, are investigated. The effects of different mixing rules are studied systematically to find out strengths and weaknesses of the models. Furthermore, the previously developed PR+COSMOSAC equation of state is also included in this work. This study is based on a large set of VLE (426 binary) and LLE (278 binary) systems covering a wide range of functional groups, temperature (from 208 to 553 K), and pressure (up to 100 MPa) to understand the range of applicability of the present approach. The MHV1 provides the best accuracy in VLE prediction among these three mixing rules, but is insensitive to pressure in the LLE prediction. The PR+COSMOSAC equation of state gives the best description of pressure effects on the LLE immiscible gap.

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