Predicting the pressure dependence of the viscosity of 2,2,4-trimethylhexane using the SAFT coarse-grained force field
File(s)Viscosity Challenge_R1.pdf (2.28 MB) Viscosity ChallengeSI_R1.pdf (2.74 MB)
Accepted version
Supporting information
Author(s)
Zheng, L
Trusler, JPM
Bresme, F
Muller, E
Type
Journal Article
Abstract
This work is framed within AIChE's 10th Industrial Fluid Properties Simulation Challenge, with the aim of assessing the capability of molecular simulation methods and force fields to accurately predict the pressure dependence of the shear viscosity of 2,2,4-trimethylhexane at 293.15 K (20 °C) at pressures up to 1 GPa. In our entry for the challenge, we employ coarse-grained intermolecular models parametrized via a top-down technique where an accurate equation of state is used to link the experimentally-observed macroscopic volumetric properties of fluids to the force-field parameters. The state-of-the-art version of the statistical associating fluid theory (SAFT) for potentials of variable range as reformulated in the Mie incarnation is employed here. The potentials are used as predicted by the theory, with no fitting to viscosity data. Viscosities are calculated by molecular dynamics (MD) employing two independent methods; an equilibrium-based procedure based on the analysis of the pressure fluctuations through a Green-Kubo formulation and a non-equilibrium method where periodic perturbations of the boundary conditions are employed to simulate experimental shear stress conditions. There is an indication that, at higher pressures, the model predicts a solid phase (freezing) which we believe to be an artefact of the simplified molecular geometry used in the modelling. A comparison (made after disclosure of the experimental data) show that the model consistently underpredicts the viscosity by about 30%, but follows the pressure dependency accurately.
Date Issued
2019-09-15
Online Publication Date
2020-05-21T06:00:27Z
Date Acceptance
2019-05-21
ISSN
0378-3812
Publisher
Elsevier
Start Page
1
End Page
6
Journal / Book Title
Fluid Phase Equilibria
Volume
496
Copyright Statement
© 2019 Elsevier B.V. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Shell Global Solutions International BV
Grant Number
PO no. 4550143956
Subjects
0203 Classical Physics
0904 Chemical Engineering
Chemical Engineering
Publication Status
Published
Date Publish Online
2019-05-21