A molecular dynamics simulation on dissolution of subcritical water in heavy oil: (I) Effect of polycyclic aromatic hydrocarbons

• Published in: Journal of petroleum science & engineering 2022-10, Vol.217, p.110934, Article 110934
• Main Authors: Yuan, Dong-Hao, Chen, Xue-Feng, Ding, Lei, Yang, Jing-Yi, Huang, Zi-Bin, Yuan, Pei-Qing
• Format: Article
• Language: English
• Subjects: Hansen solubility parameters; Molecular dynamics simulation; Polycyclic aromatic hydrocarbons; Solubility; Subcritical water
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/j.petrol.2022.110934

Molecular dynamics simulations were applied to characterize the dissolution of subcritical water (Sub-CW) in polycyclic aromatic hydrocarbons (PAHs). The phase equilibria of Sub-CW/PAHs are characterized by the dissolution of Sub-CW in PAHs. The solubility of Sub-CW increases with temperature but is relatively insensitive to pressure changes. Furthermore, an increase in PAH scale leads to a decrease in Sub-CW solubility. The PAH-rich phase can be divided into an interface region and a bulk region, and the water concentrations in the two regions differ greatly. The Hansen solubility parameters of PAHs and Sub-CW exhibit opposite distributions, hindering the mutual solubility between the two. The dissolution of Sub-CW is promoted by the destruction of intermolecular hydrogen bonds of water at increasing temperature, but is ultimately inhibited by the difference in dispersion properties between PAHs and Sub-CW. According to the Gibbs solvation free energy, the electrostatic interaction between PAHs and Sub-CW favors the dissolution of Sub-CW. Meanwhile, the van der Waals interaction shows different effects. •Phase equilibria of PAHs and Sub-CW were studied by MD simulation.•Phase equilibria of PAHs and Sub-CW feature dissolution of Sub-CW in PAHs.•Solubility of Sub-CW in PAHs is sensitive to temperature change.•Opposite distributions of Hansen HSP hinder dissolution of Sub-CW in PAHs.•Electrostatic interaction promotes dissolution of Sub-CW in PAHs.