Stabilized density gradient theory algorithm for modeling interfacial properties of pure and mixed systems

TL;DR

This paper introduces a stabilized density gradient theory (SDGT) algorithm that accurately models interfacial properties of pure and mixed systems without needing a reference substance, using PC-SAFT EoS for improved predictions.

Contribution

The work presents a novel SDGT algorithm that enhances DGT calculations by removing the need for a reference substance and integrating PC-SAFT EoS for better accuracy in interfacial property predictions.

Findings

Accurately predicts interfacial properties without reference substance.

Demonstrates good agreement with experimental data.

Ensures numerical stability for practical applications.

Abstract

Density gradient theory (DGT) allows fast and accurate determination of surface tension and density profile through a phase interface. Several algorithms have been developed to apply this theory in practical calculations. While the conventional algorithm requires a reference substance of the system, a modified "stabilized density gradient theory" (SDGT) algorithm is introduced in our work to solve DGT equations for multiphase pure and mixed systems. This algorithm makes it possible to calculate interfacial properties accurately at any domain size larger than the interface thickness without choosing a reference substance or assuming the functional form of the density profile. As part of DGT inputs, the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) was employed for the first time with the SDGT algorithm. PC-SAFT has excellent performance in predicting liquid phase properties as well as phase behaviors. The SDGT algorithm with the PC-SAFT EoS was tested and compared with experimental data for several systems. Numerical stability analyses were also included in each calculation to verify the reliability of this approach for future applications.