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Updated: Nov 11, 2025

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Revisiting Kelvin equation and Peng-Robinson equation of state for accurate modeling of hydrocarbon phase behavior in
Ilyas Al-Kindi1, Tayfun Babadagli2
1Department of Civil and Environmental Engineering, School of Mining and Petroleum Engineering, University of Alberta, 7-277 Donadeo Innovation Centre for Engineering, 9211-116th Street, Edmonton, AB, T6G 1H9, Canada.
Abstract:
The thermodynamics of fluids in confined (capillary) media is different from the bulk conditions due to the effects of the surface tension, wettability, and pore radius as described by the classical Kelvin equation. This study provides experimental data showing the deviation of propane vapour pressures in capillary media from the bulk conditions. Comparisons were also made with the vapour pressures calculated by the Peng-Robinson equation-of-state (PR-EOS). While the propane vapour pressures measured using synthetic capillary medium models (Hele-Shaw cells and microfluidic chips) were comparable with those measured at bulk conditions, the measured vapour pressures in the rock samples (sandstone, limestone, tight sandstone, and shale) were 15% (on average) less than those modelled by PR-EOS.
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