LCVM model

Figure 5.1.1. VLE prediction for the methanol and benzene binary system at 293 K by various methods. Circles represent experimental data, the solid line with crosses shows the UNIFAC predictions, and the smooth solid line denotes the results of the WS model. The large, medium, and short dashed lines are from the HVOS, HVO, and MHVl models, respectively the dotted line is from the MHV2 model and the dot-dash line reflects the results of the LCVM model. (Points are VLE data from the DECHEMA Chemistry Series, Gmehling and Onken 1977, Vol. 1, Pt, 2a, p. 220 the data file name on the accompanying disk for this system is MB20.DAT.)...

Figure 5.2.1. Infinite dilution activity coefficients of -alkanes in hexane. The dots denote experimental data (Kniaz 1991) the solid line represents the UNIFAC predictions the large, medium, and short dashed lines are from HVOS, HVO, and MHVl models, respectively the dotted line is from MHV2 model and the dot-dash line reflects results from the LCVM model.

As mentioned earlier, because the present excess free-energy models used in the EOS-G formalism were developed for mixtures of pure liquids, in principle the EOS-G approach is applicable to mixmres in which all constituents exist as pure liquids at the temperature and pressure at which temperature-independent model parameters of the excess free-energy model (here UNIFAC) have been evaluated. Using such models to describe the mixture of a supercritical gas dissolved in a liquid is an approximation that has certain consequences, as we discuss later in this section. The EOS-G models used so far to describe gas solubility are the approximate mixing rules such as the MHV2, HVOS, or LCVM models, and we will restrict our discussions to these models. 

We first investigated the behavior of mixtures of the normal paraffinic solvents pentane, heptane, and decane with gaseous methane. These mixtures consist of two main UNIFAC groups, methane and the main methyl group CH2 thus, there are only two binary interaction parameters to evaluate. We used the VLE data for the 377 K isotherm of the methane and n-heptane mixture to obtain these parameters for both the HVOS and LCVM models the parameter values are reported in Table 5.3.1. We then estimated the VLE at all other temperatures of the three mixtures. The results... 

Group Pair HVOS Model LCVM Model... 

Boukouvalas, C., Spiliotis, N., Coutsikos, P., and Tzouvaras, N., 1994. Prediction of vapor-liquid equilibrium with the LCVM model. A linear combination of the Huron-Vidal and Michelsen mixing rules coupled with the original UNIFAC and the t-mPR equation of state. Fluid Phase Eq., 92 75-106. 

The LCVM model (Boukouvalas et al., 1994) is based on a mixing rule which is a Linear Combination of the Vidal and Michelsen (MHV-l) mixing rules ... 

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