Thomas E. Daubert

Extension of UNIFAC to high pressure VLE using Vidal mixing rules

Abstract The UNIFAC and ASOG group contribution methods are extensively used for predicting vapor—liquid equilibria at low pressures. At higher pressures, these models are not applicable—primarily because there is no consistent way of correcting for vapor phase non-idealities. In this work the UNIFAC model was incorporated in an equation of state framework using Vidal mixing rules. Excellent prediction results are obtained at high pressures for highly non-ideal systems. The method serves as a convenient way to extend the applicability of the group-contribution models to higher pressures.

The temperature dependence of the hard sphere diameter

Abstract The temperature dependence of the equivalent hard sphere diameter is analyzed using statistical mechanics. The analysis shows that algebraic equations for the hard sphere diameter which were developed by previous workers are not consistent with the statistical mechanics at high temperature. An algebraic equation which is consistent with the statistical mechanics is developed.

A study of density-dependent local composition mixing rules for prediction of multicomponent phase equilibria

Abstract Density-dependent local composition (DDLC) mixing rules have the potential to correlate highly non-ideal systems. These rules were thoroughly tested for their ability to correlate binary systems and to predict multicomponent systems with a Carnahan-Starling-Redlich-Kwong-UNIQUAC model. It is concluded that prediction results for multicomponent systems are generally superior with the non-conformal model. Nevertheless, in many cases the conformal mixing rules predicted results comparable with the local composition model.

TRANSPORT PROPERTY DATA QUALIFICATION FOR VARYING FUNCTIONAL GROUPS

Abstract A qualitative study of the accuracy and consistency of transport property experimental data was undertaken for compounds which are not categorized in particular homologous series but contain a common hydrocarbon chain and differing functional groups. The behaviors of liquid and vapor viscosity and vapor thermal conductivity were observed over a reasonable temperature range. Plots of property against temperature or reduced temperature were analyzed for consistent alignment among different properties and groups of compounds. Trends were similar to past work on thermodynamic properties. Results of the study provide methods to verify data accuracy, predict positioning of data within functional group categories, and allow rough prediction for multifunctional compounds.