Rigorously Universal Methodology of Volume Translation for Cubic Equations of State

Abstract

To model systems typically found in hydrocarbon production problems and the chemical industry, there are three basic types of calculations are required: phase equilibria, volumetric behavior, and thermophysical properties. Since 1972, cubic equations of state (CEoS) have shown surprising capabilities in the prediction of the phase equilibria of complex nonpolar systems. However, the prediction of the liquid volumes from cubic equations of state, despite the recently important advances in CEoS/A E mixing rules, still remains the weak point of this type of equations. A rigorous, universal, but simple methodology without introducing any regressed parameters is proposed for the volume translation for all types of cubic equation of state. The proposed methodology applies to not only defined components but also petroleum fractions. The translated cubic equations of state reproduce almost exactly the liquid density over the entire temperature range from the triple point to the critical point.

Phase behavior of heavy oil–solvent mixture systems under reservoir conditions

“…where M is the molecular weight and e and d are constants equal to 0.1823 and 2.258, respectively. Furthermore, Peneloux et al (1982) and Twu and Chan (2009) proposed two correlations to estimate C, as shown in Eqs. ( 21) and ( 22):…”

Modeling of ionic liquid+polar solvent mixture molar volumes using a generalized volume translation on the Peng–Robinson equation of state

“…However, one of the major problems of these equations is that they cannot predict the density of liquids accurately. A comparison of predicted molar masses of liquids by cubic equations of state and the experimental values indicated systematic deviations [26,27] which could be decreased by adding a constant to the predicted molar mass as follows [17]. (1) in which,the c parameter represents a systematic deviation [17].…”

“…In general, applying a volume-translation technique to an equation of state can increase the accuracy of liquid phase density predictions [25][26][27]. For example, Tsai and Chen [17] reported that the results of a volumetranslated Peng-Robinson (VTPR) equation of state are better than the conventional cubic EoS for predicting the liquid molar volume of pure components, as well as mixtures.…”

A Novel Theory for Predicting Critical Constants and the α Function for Pure Polymers

“…Twu and Chan 30 have successfully developed a rigorous, universal, but simple volume-translation methodology for the accurate prediction of the liquid density from cubic equations of state for components without introducing any regressed parameters. This technology of volume-translated CEoS will now be applied to the polymer system for the correction of liquid volume.…”

“…The methodology developed by Twu and Chan offers a convenient way to select any reference temperature for the volume correction. They pointed out that the accuracy of volume translation depends primarily on the selected reference temperature, not the reference component.…”