Volumetric Properties of Propane, n-Octane, and Their Binary Mixtures at High Pressures

Abstract

Density, isothermal compressibility, isobaric expansivity, thermal pressure coefficient, and excess volumes for binary mixtures of propane + n-octane are reported over a wide range of temperatures (from 320 to 440 K), and pressures (up to 400 bar) for mixture compositions with 0, 20.4, 42.4, 58.9, 79.7, and 100 wt % propane. Densities were determined using a fully computerized variable-volume view-cell system. A motorized pressure generator is used to bring about changes in the position of a movable piston in the cell at controlled and adjustable rates thereby bringing about changes in the internal volume and thus pressure. A long stroke-length linear variable differential transformer is used to continually monitor the position of the piston and thus the cell volume in real-time. Knowing the initial loading of the cell and the cell volume at any moment as pressure is altered permits generation of continuous density profiles along pressure scans in increasing (compression) or decreasing (decompression) dir...