Molecular dynamics simulation of the key characteristics of the supercritical CO2–pentaerythritol tetraacetate system

Abstract

Supercritical CO₂ is widely used in many fields of industry. Investigation of statistical mechanics of CO₂ fluid under quasi critical and supercritical state has great significance. Equilibrium molecular dynamics (EMD) simulations are carried out to investigate the statistical mechanics and macroscopic performance of CO₂ fluid under the quasi critical and supercritical state. The results show that the bond length and bond angle distributions for supercritical CO₂ are Gaussian distribution basically. The dimers’ proportion of supercritical CO₂ system changes with pressure increasing. T-type dimer has high share within the system when pressure is higher than 9MPa. It can be inferred that T-type dimer leads to CO₂ physical properties changing tempestuously under supercritical state. The effect that lubricating oil has on microstructure and heat transfer of supercritical CO₂ is also investigated in the present work. The results show the lubricating oil produces significant effect on the dimers’ structure under low pressure.