(204p) Estimation of Kinematic Viscosity for CO2 expanded Liquids By Asog-Visco Method

A mixture of CO₂ and a co-solvent is widely employed as a solvent or mobile phase for supercritical fluid extraction, chemical reaction, supercritical fluid chromatography etc. In particular, CO₂ expanded liquid (CXL), a liquid phase in a mixture of pressurized CO₂ gas and a liquid organic solvent at gas–liquid phase equilibrium, CXL is expected to provide advantages in these processes because the pressure is lower than the critical pressure and their unique properties can be modified significantly with the small changes in temperature and/or pressure. Kinematic viscosity is one of important transport properties, and is required for designing chemical process as well as estimating dimensionless numbers such as Reynolds number, Schmidt number, Prandtl number [1,2]. A more accurate estimation method for kinematic viscosity is increasingly demanded. The authors have proposed the estimation method, that is, the ASOG-VISCO method by which the excess Gibbs free energy at transition state in the Eyring kinetic equation is obtained by the group contribution method. In fact, the parameters for functional groups such as CH₂, ArCH, CyCH, OH, H₂O, CO, COO, CCl₃, and CCl₄ were determined using the literature data on kinematic viscosities experimentally measured, and those for binary and ternary mixtures consisting of hydrocarbons, alcohols, water, ketones, esters, trichlorides and carbon tetrachloride were estimated with accuracies of 4.2 and 5.0 % for binary and ternary mixtures, respectively [3,4]. In this presentation to estimate kinematic viscosities for binary mixtures using the ASOG-VISCO model, the group parameters were determined from kinematic viscosities of binary mixtures for CO₂ and compounds having functional groups such as CH₂, OH and CO under gas-liquid equilibria conditions. The model was applied to estimate the kinematic viscosities for binary mixtures of saturated carbon dioxide and organic compounds such as paraffins, alcohols, and ketones. The predicted results have been compared with those using the McAllister model [5].

Reference:

1) B. E. Poling, J. M. Prausnitz, J. P. O’Connell: The Properties of GASES AND LIQUIDS, fifth edition, McGraw Hill (2001)

2) T. Funazukuri, Y. Ishiwata, N. Wakao: AIChE J., 38, 1761 (1992)

3) A. Murata, K. Tochigi, H. Yamamoto: Molecular Simulation, 15, 451 (2004)

4) K. Tochigi, K. Yoshino, V. K. Rattan: Int. J. Thermophys., 26, 413 (2005)

5) R. A. McAllister: AIChE J., 6, 427 (1960)