Direct visualization and molecular simulation of dewpoint pressure of a confined fluid in sub-10 nm slit pores

The fluid phase behavior characterization at nanoscale is a challenging and significant problem for many processes such as polymer analysis, drug delivery, carbon dioxide storage, and petroleum production, among others. It is commonly accepted that the fluid phase behavior in sub-10 nm pores is considerably different than the phase behavior in bulk environment. In this study, experiments using the lab-on-a-chip approach has been conducted to measure and visualize n-Butane condensation pressure in nano-scale slit pores of 50 nm, 10 nm, and 4 nm. The result shows that n-Butane dewpoint pressure can deviate as high as 14% from its original value due to the confinement effect. Molecular simulation has also been performed with a purpose to model the experimental results. The simulation results show a good agreement with the experimental data and prove the significant impact of the confinement effect.