UNIFAC calculation of thermodynamic properties of binary 1-chloroalkane + alkane and α,ω-dichloroalkane + alkane mixtures: Comparison with Nitta–Chao and DISQUAC predictions

2003 ◽  
Vol 81 (5) ◽  
pp. 392-405 ◽  
Author(s):  
J García ◽  
E R López ◽  
M JP Comuñas ◽  
L Lugo ◽  
J Fernández
Keyword(s):  
Thermodynamic Properties ◽  
Proximity Effect ◽  
Interaction Parameters ◽  
Mean Deviation ◽  
Geometrical Parameters ◽  
Unifac Model ◽  
Methylene Groups ◽  
Using Data ◽  
Vapor Liquid Equilibria ◽  
Parameter Values

Data available in the literature for vapor–liquid equilibria, activity coefficients at infinite dilution, and enthalpies of mixing for binary mixtures of 1-chloroalkanes or dichloroalkanes with alkanes are used to determine interaction parameters for three versions of the UNIFAC model – the Tassios et al., Larsen et al., and Gmehling et al. versions. The interaction parameters for chlorine and methyl or methylene groups are calculated using data for the thermodynamic properties of 1-chloroalkane + alkane mixtures. In the case of the Gmehling version, the geometrical parameters for chlorine are also determined. In addition, structure-dependent interaction parameters for α,ω-dichloroalkane + alkane mixtures are presented, taking into account the proximity effect. When the two chlorine atoms of the dichloroalkane are more separated, they become more independent, and the reported values of the interaction parameters approach those of 1-chloroalkane. For all of the properties studied the mean deviation obtained with the new parameter values is lower than that obtained with older values. The results for the thermodynamic properties obtained using the new parameters of the three versions of UNIFAC are compared with those of DISQUAC and Nitta–Chao models. Key words: alkanes, chloroalkanes, DISQUAC, excess thermodynamic properties, proximity effect, UNIFAC.

DISQUAC predictions on thermodynamic properties of ternary and higher multicomponent mixtures. II. Results for HE of ternary mixtures containing nonpolar components, or one polar compound, two polar compounds, or one alcohol and hydrocarbons, or CCl4

2001 ◽  
Vol 79 (10) ◽  
pp. 1447-1459 ◽  
Author(s):  
Juan Antonio Gonzalez ◽  
Javier Carmona ◽  
Nicolas Riesco ◽  
Isaias Garcia de la Fuente ◽  
Jose Carlos Cobos
Keyword(s):  
Thermodynamic Properties ◽  
Binary Systems ◽  
Ternary Systems ◽  
Polar Compounds ◽  
Ternary Mixtures ◽  
Mean Deviation ◽  
Group Contributions ◽  
Polar Compound ◽  
The Mean ◽  
Vapor Liquid Equilibria

The ability of the DISQUAC model for predicting excess enthalpies (HE) of ternary systems on the basis of binary parameters only, i.e., neglecting ternary interactions is analyzed. At this end, DISQUAC results for a set of 95 ternary systems are examined. The solutions studied are formed by only hydrocarbons (or CCl4); or by one polar compound (not alcohols) and two hydrocarbons (or CCl4); or by two polar compounds (not alcohols) and one hydrocarbon (or CCl4); or by one alcohol and two hydrocarbons (or CCl4). Most of the HEs analyzed are endothermic, and valid at 298.15 K and atmospheric pressure. The mean deviation between experimental values and DISQUAC results is 5.5% for the ternary systems and 6.5% for the constituent binaries (181 mixtures). The interaction parameters used are valid for the description of thermodynamic properties of binary systems: vapor–liquid equilibria (VLE), liquid–liquid (LLE), and solid–liquid equilibria (SLE), HE and excess heat capacities at constant pressure (CEP), as well as HE and VLE of ternary solutions. Predictions are, in most of the cases, independent of the mixture compounds, or the number of groups present in the system. Larger deviations underline typical shortcomings of the group contributions methods (e.g., Patterson's effect; branching). Note that results for the ternaries and for the constituent binaries are of the same order. This is not the case for the Dortmund version of UNIFAC. The mean deviations obtained using this model are 10.5% and 14% for the ternary and binary mixtures, respectively. Results from other models (original UNIFAC, Flory's theory, Nitta–Chao, UNIQUAC association model) for a number of systems are also compared to those obtained using DISQUAC.Key words: predictions, HE, ternary systems, binary parameters, geometrical methods, Flory, group contributions.

scholarly journals Modelling temperature variations in polar snow using DAISY

1997 ◽  
Vol 43 (143) ◽  
pp. 180-191 ◽  
Author(s):  
Ε. M. Morris ◽  
H. -P. Bader ◽  
P. Weilenmann
Keyword(s):  
Field Experiments ◽  
A Priori ◽  
Model Parameters ◽  
Data Set ◽  
International Geophysical Year ◽  
Snow Model ◽  
Using Data ◽  
Polar Snow ◽  
Parameter Values ◽  
The Antarctic

AbstractA physics-based snow model has been calibrated using data collected at Halley Bay, Antarctica, during the International Geophysical Year. Variations in snow temperature and density are well-simulated using values for the model parameters within the range reported from other polar field experiments. The effect of uncertainty in the parameter values on the accuracy of the predictions is no greater than the effect of instrumental error in the input data. Thus, this model can be used with parameters determined a priori rather than by optimization. The model has been validated using an independent data set from Halley Bay and then used to estimate 10 m temperatures on the Antarctic Peninsula plateau over the last half-century.

New Group-Interaction Parameters of the UNIFAC Model:  Aromatic Methoxyl Binaries

2001 ◽  
Vol 40 (7) ◽  
pp. 1740-1747 ◽  
Author(s):  
Shou-Ming Hwang ◽  
Ming-Jer Lee ◽  
Ho-mu Lin
Keyword(s):  
Group Interaction ◽  
Interaction Parameters ◽  
Unifac Model

scholarly journals Application of COSMO-RS Method for the Prediction of Liquid-Liquid Equilibrium of Water/n-Dodecane/1-Butanol

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
S. Balasubramonian ◽  
Shekhar Kumar ◽  
D. Sivakumar ◽  
U. Kamachi Mudali
Keyword(s):  
Activity Coefficient ◽  
Mutual Solubility ◽  
Solubility Data ◽  
Interaction Parameters ◽  
Binary Interaction ◽  
Liquid Equilibrium ◽  
Model Interaction ◽  
Uniquac Model ◽  
Unifac Model ◽  
Lle Data

The liquid-liquid equilibrium (LLE) for the system water-dodecane-butanol was estimated using the UNIQUAC model. In the UNIQUAC model interaction parameters were estimated from the vapor-liquid equilibrium (VLE) and LLE data of their constituent binary pairs. The water-dodecane-butanol LLE was experimentally measured at 298.15 K. Phase stability constraints were taken into account while calculating the binary interaction parameters from the mutual solubility data. The COSMO-RS method was used to estimate the activity coefficient in the miscible binary pair. The ternary LLE composition was predicted using the experimental VLE data as well as using the COSMO-RS calculated activity coefficient data along with the experimental mutual solubility data. In the latter case the root mean square deviation (RMSD) for the distribution of butanol between aqueous and organic phase is 0.24%. The corresponding UNIFAC model prediction is 7.63%.

Topological study on the proximity effect on methylene groups in dimethoxyethers

2002 ◽  
Vol 617 (1-3) ◽  
pp. 219-224 ◽  
Author(s):  
Antonio Vila ◽  
Enrique Carballo ◽  
Ricardo A. Mosquera
Keyword(s):  
Proximity Effect ◽  
Methylene Groups
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