Fluid group contribution method

QSAJi Methods for Fluid Solubility Prediction. Several group contribution methods for predicting Hquid solubiHties have been developed. These methods as weU as other similar methods are often called quantitative stmcture-activity relationships (QSARs). This field is experiencing rapid development. 

Mokbel, I., Rauzy, E., Meille, J.P., Jose, J. (1998) Low vapor pressures of 12 aromatic hydrocarbons. Experimental and calculated data using a group contribution method. Fluid Phase Equil. 147, 271-284. 

Constantinou, L., R. Gani, and J. P. O Connell, "Estimation of the acentric factor and the liquid molar volume at 298K through a new group contribution method". Fluid Phase Equilibria 103, 11, (1995). 

A Quantum Chemistry based Alternative to Group Contribution Methods for the Prediction of Activity Coefficients in Multi-Component Mixtures. Fluid Phase Equilibria, 2000, 372, 43. 

A study of the representation of liquid-fluid equilibria with the "Excess Function-Equation of State" model and the choice of a group-contribution method. Promising results were obtained here (references [3] and [4]). 

A study of the "continuity" of the model when changing from the solid-fluid to the liquid-fluid field for a fixed mixture application and "adjustment" of the group-contribution method. It is this third stage and its results that we present below. 

The interaction parameters of the form (10) are appropriate for the liquid-fluid equilibria for a large number of compounds [4], A study of the "continuity" of the model in the field of solid-fluid equilibria is a pre-requisite for the development of a single all-purpose group -contribution method. 

The calculation of the liquid-fluid equilibria with the group contribution method has been presented elsewhere [4], The matrix of the parameters of group interaction (Table 1) contains values readjusted relative to the matrix obtained considering only liquid-fluid equilibria [4], These parameters are Ai5, A35, A45 and A59. The introduction of supplementary increments for the form of the molecules (a3 and P3.5) enables good results to be obtained for the calculation of solid-fluid equilibria and does not essentially modify the representation of liquid-fluid equilibria. The average relative deviation 5r(x) for the experimental data as a whole is 16 7% for the group contribution method and 13.3% for the model with E12 adjusted. The experimental data concern 40 isotherms (P,x) for 11 binary mixtures of solid aromatic hydrocarbon with supercritical C02. 

Further, molecular simulation and computational chemistry have evolved, and are evolving, into important tools for developing better characterization techniques where it is not possible to measure all data. Even so, it is precisely the molecular complexity of petroleum fluids that seems to be an inhibiting factor in the use of these methods for developing better characterization methods. However, identification of important functional groups in petroleum fluids applying molecular simulation and/or computational chemistry for use with group contribution methods to predict thermo-physical properties may be an area for further research. 

Tu CH. Group-contribution method for the estimation of vapor pressures. Fluid Phase Equilibria 1994 99 105-20. 

Gardas RL, Coutinho JAP (2008) Extension of the Ye and Shreeve group contribution method for density estimation of ionic liquids in a wide range of temperatures and pressures. Fluid Phase Equilib 263 26-32... 

Yinghua L, Peisheng M, Ping L (2002) Estimation of liquid viscosity of pure compounds at different temperatures by a corresponding-states group-contribution method. Fluid Phase Equilib 198 123-130... 

Saini, R., G. A. Melhem, and B. M. Goodwin. 1991. A modified cubic equation of state with binary parameters predicted from a group contribution method. Paper presented at the 2d International Symposium on Supercritical Fluids. Boston, MA, May. 

Le Thi, C., Tamouza, S., Passarello, J.P., Tobaly, R, de Hemptinne, J.-C., 2006. Modeling phase equilibrium of H-2-tn-alkane and COj-l-n-alkane binary mixtures using a group contribution statistical association fluid theory equation of state (GC-SAFT-EOS) with a k(ij) group contribution method. Ind. Eng. Chem. Res., 45 6803-6810. 

Peters, F.T., Laube, F.S., Sadowski, G., 2012. Development of a group contribution method for polymers within the PC-SAFT model. Fluid Phase Equilib., 324 70. 

Dissertation, Universiteit Leiden, Leiden, The Netherlands Vitu, S. Jaubert, J.N. Mutelet, F. (2006). Extension of the PPR78 model (Predictive 1978, Peng Robinson EoS with temperature dependent kij calculated through a group contribution method) to systems containing naphtenic compounds. Fluid Phase Equilib, Vol.243, pp. 9-28... 

Physical properties such as density, viscosity, thermal conductivity, and heat capacity are generally not a serious problem in simulation. The group-contribution methods are reasonably good, and simulator databank include experimental heat capacity data for more than a thousand substances. Although these correlations have random and systematic errors of several percent, this is close enough for most purposes. (However, they are not sufficient when you are paying for a fluid crossing a boundary based on volumetric flowrate.) As noted in Section 13.2.2. one should always be aware of which properties are estimated and which are from experimental measurements. 

Wu K-J, Zhao C-X, He C-H (2013) Development of a group contribution method for determination ofthermal concuctivitry of ionic liquids. Fluid Phase Equilib 339 10-14... 

GME 88] Gmehling J., Present status of group-contribution methods for synthesis and design of chemical processes , Fluid Phase Equilibria, vol. 144, pp. 37-47, 1988. 

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