Estimation of Compressibility Factor of Saturated Liquid and Vapor of Bulk and Nanoconfined Methane

Abstract

In this work, compressibility factor of saturated liquid, saturated vapor and critical compressibility factor of bulk and confined methane are investigated. We have first comparedthe experimental data of compressibility factor of saturated liquid, saturated vapor and critical compressibility factor with the corresponding simulation data of current work.The experimental compressibility factor of saturated liquid and vapor and critical compressibility factor are in good agreement with the data obtained using molecular simulation approach of current work. Further, we have estimated the compressibility factor of saturated liquid and saturated vapor of nanoconfined methane at various reduced temperatures in a given pore width. Estimated compressibility factor of saturated liquid increases with increase in temperature and the compressibility factor of saturated vapor decreases with increases in temperature for all studied nanopore width, H = 40Å to 5.4Å. It has been observed that with increase in reduced temperature, change in compressibility factor of saturated liquid is comparatively less than the change in compressibility factor of saturated vapor. Critical compressibility factor is estimated for all studied nanopore width using critical point data obtained from the simulation.Critical compressibility factor of bulk methane and methane confined in 40Ånanopore width are approximately same. Further from 30Åto 8Ånanopore width critical compressibility factor is monotonically decreasing and then from 8Å to 5.4Ånanopore width it remains indifferent reflecting quasi-2D behaviour of nanoconfined methane.