A new method for evaluation of UNIFAC interaction parameters

Fluid Phase Equilibria, 2014

This paper describes an algorithm for the computation of the UNIQUAC interaction parameters 21 from liquid-liquid experimental data. The algorithm comprises two separate levels. The inner level 22 is devoted to the calculation of the interaction parameters, minimizing an objective function which 23 is function of the activities. The outer level uses the parameters by the inner level and aims to 24 minimize the error between experimental and calculated molar fractions through an adjustment of 25 the experimental molar fractions, provided that the condition of common tangent to the change of 26 the Gibbs free energy of mixing is matched.

Fluid Phase Equilibria, 2002

The objective of this work was to improve the accuracy of group contribution models for prediction of solvent activities in polymer solutions by revising UNIFAC group interaction parameters using a wide range of vapor-liquid equilibrium (VLE) data of solvent-polymer systems. The group contribution models considered in this work were UNIFAC-FV, Entropic-FV, GK-FV and UNIFAC-ZM models. A total of 142 systems that consisted of 16 polymers and 36 solvents containing a large variety of solvent-polymer systems ranging from non-polar to polar substances were considered to optimize 46 pairs of group interaction parameters. Data considered were split up into systems containing alkane and cycloalkane, aromatic, and polar solvents. For athermal systems, the UNIFAC-FV model gave the best results. Therefore, the model was used in optimizing the group parameters. Revised group interaction parameters were found to improve the reliability of VLE predictions in solvent-polymer systems. A significant improvement of prediction results was achieved by UNIFAC-FV model from 20.0 to 10.8% absolute average deviation (AAD) in solvent activities for systems containing polar solvents and from 16.7 to 10.9% AAD for all systems. The prediction results of GK-FV and UNIFAC-ZM models were also improved.

2015

The isobaric vapor-liquid equilibrium data predictions for the binary system of cyclopentyl methyl ether and cyclopentanol were obtained using UNIFAC and modified UNIFAC Dortmund method. Group identification was done by using artist free software with Dortmund Data Bank . The interaction parameters in the UNIFAC and modified UNIFAC Dortmund method, for the ether group (-CH3O) and alcohol (-OH), were used to predict VLE data. Thermodynamic consistency of the predicted VLE data had been checked by the Herington method. The predicted data were correlated with Van Laar, Wilson and NRTL activity coefficient models. The binary interaction parameters of models had been obtained by regression. The predicted VLE data of UNIFAC method were fitted much more accurately than that of modified UNIFAC Dortmund method by these activity coefficient models Van Laar, Wilson and NRTL.

Fluid Phase Equilibria, 1993

Ortega, J. and Legido, J.L., 1993. Revision of interaction parameters for estimating the enthalpies of mixtures of benzyl ethanoate + n-alkanes or I-chloroalkanes using the UNIFAC model with presentation of new experimental data.

Fluid Phase Equilibria, 2013

The vaporization enthalpy is regarded as a measure of molecular interactions in the vapor/liquid phase. It has a number of applications in chemical and petrochemical processes in which vapor-liquid equilibrium exists. Acree and Chickos [1], recently published a comprehensive compilation of phase change enthalpies, including vaporization enthalpies of pure organic compounds. This collection of vaporization enthalpies for 2811 compounds at the standard temperature of 298.15 K was used in this study for the development of a predictive model. The compounds in the collection are composed of a combination of the following atoms, viz. carbon, hydrogen, nitrogen, oxygen, phosphorous, sulfur, fluorine, chlorine, bromine, and iodine. This paper presents a reliable group contribution model for the prediction of the vaporization enthalpies of organic compounds. The group contribution model developed is able to predict the standard molar enthalpies of vaporization to within an average absolute relative deviation of 3.7%, which is of sufficient accuracy for many practical applications in chemical and petrochemical engineering.

International Journal of Thermophysics, 1989

The Dortmund Data Bank (DDB) was started in 1973 with the intention to employ the vast store of vapor-liquid equilibrium (VLE) data from the literature for the development of models for the prediction of VLE. From the beginning, the structure of the DDB has been organized in such a way that it was possible to take advantage of the full potential of electronic computers. With the experience gained in fitting and processing VLE data, we extended the DDB system to other types of mixture properties, i.e., liquid-liquid equilibria (LLE), gas solubilities (GLE), activity coefficients at infinite dilution (7 ~), heats of mixing (hE), and excess heat capacities. Besides the files for mixture properties, the DDB contains pure-component data and program packages for various applications. New experimental data are checked for consistency before they are stored. For data retrieval user-specified search masks can be used. The data files are available via an online data service and through the Dechema Chemistry Data Series. For the purpose of data correlation and model testing, parameter fitting is performed with an optimization routine (Nelder-Mead). In the past years the DDB system has been successfully employed for the development of prediction methods for VLE, LLE, GLE, 7~, and h z (UNIFAC, mod. UNIFAC, etc.).

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 2009

This paper deals with the determination of recommended temperature dependent NRTL parameters by simultaneous correlation of VLE-, γ γ γ γ γ ∞ ∞ ∞ ∞ ∞-, and h E data from the Dortmund Data Bank (DDB) using an interactive program package. Correlation results for selected mixtures are discussed in detail. The program package RECVAL is directly interfaced to the Dortmund Data Bank, makes extensive use of graphics for data representation and may be extended for the correlation and prediction of further mixture or pure component data. To ensure rapid conversion in case of a large amount of data, simultaneous convergence of the outer parameter fitting loop and the inner phase equilibrium iterations is employed. Recommended temperature dependent NRTL parameters have been determined for 133 binary systems. These parameters have been obtained by a simultaneous fit to VLE-, γ γ γ γ γ ∞ ∞ ∞ ∞ ∞-, and h E-data stored in DDB.

Thermochimica Acta, 1996

Literature data on enthalpies of mixing and vapor-liquid equilibria of organic linear carbonates + n-alkanes mixtures examined on the basis of the UNIFAC model (in its original version as well as in those of Tassios et al., Larsen et al. and Gmehling et al.). For the four versions of the UNIFAC model, the interaction parameters for the carbonate group, O CO O, and the methyl and methylene groups, CH 3, CH 2, respectively, are reported. In the case of the Gmehling version, the geometrical parameters of the carbonate group are also determined. The best predictions are achieved with the Gmehling version, with mean deviations of 4.4% for the excess Gibbs energies and 2.3% for the excess enthalpies.

2015

ThermoML is an Extensible Markup Language (XML)-based new IUPAC standard for storage and exchange of experimental, predicted, and critically evaluated thermophysical and thermochemical property data. The basic principles, scope, and description of all structural elements of ThermoML are discussed. ThermoML covers essentially all thermodynamic and transport property data (more than 120 properties) for pure compounds, multicomponent mixtures, and chemical reactions (including change-of-state and equilibrium reactions). Representations of all quantities related to the expression of uncertainty in ThermoML conform to the Guide to the Expression of Uncertainty in Measurement (GUM). The ThermoMLEquation schema for representation of fitted equations with ThermoML is also described and provided as supporting information together with specific formulations for several equations commonly used in the representation of thermodynamic and thermophysical properties. The role of ThermoML in global data communication processes is discussed. The text of a variety of data files (use cases) illustrating the ThermoML format for pure compounds, mixtures, and chemical reactions, as well as the complete ThermoML schema text, are provided as supporting information.

Fluid Phase Equilibria, 2002

Isobaric vapour-liquid equilibria have been experimentally determined for the binary systems methanol+dimethyl carbonate, ethanol + dimethyl carbonate, dimethyl carbonate + 1-propanol, dimethyl carbonate + 1-butanol and dimethyl carbonate + 1-pentanol at 101.3 kPa. The activity coefficients were calculated to be thermodynamically consistent and were correlated with the Wilson and UNIQUAC equations. Interaction parameters related to the carbonate group (-OCOO-) and alcohols, in ASOG and UNIFAC methods, have been determined using our experimental VLE data. The experimental results, as well as those by other authors, agree with the calculated VLE using the new ASOG and UNIFAC parameters.