Issue 46, 2022

Thermodynamics of supercritical carbon dioxide mixtures across the Widom line

Abstract

Supercritical carbon dioxide (scCO2) mixtures are essential for many industrial applications. However, the knowledge of their thermophysical properties in the extended critical region is insufficient. Here, supercritical liquid- and gas-like regions dominated by distinct dynamics and thermodynamics exist and are demarcated by the so-called Widom line. The nature of the anomalies observed for several thermophysical properties at the crossover between these two regions is the subject of a lively debate. Hence, the extended critical region of scCO2 and seven of its binary mixtures with hydrogen, methane, ethane, isobutane, benzene, toluene or naphthalene is studied with respect to thermodynamic, transport and structural properties on the basis of molecular dynamics simulations and equation of state calculations. The Widom line is evaluated employing five criteria and a new empirical equation is proposed for its prediction. Further, the crossover anomalies are investigated in the light of pseudo-boiling theory, diffusion and viscosity as well as structural characteristics given by the radial distribution function.

Graphical abstract: Thermodynamics of supercritical carbon dioxide mixtures across the Widom line

Supplementary files

Article information

Article type
Paper
Submitted
14 Jun 2022
Accepted
07 Nov 2022
First published
08 Nov 2022
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2022,24, 28257-28270

Thermodynamics of supercritical carbon dioxide mixtures across the Widom line

D. Saric, G. Guevara-Carrion and J. Vrabec, Phys. Chem. Chem. Phys., 2022, 24, 28257 DOI: 10.1039/D2CP02701A

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