Excess volume, isothermal compressibility, isentropic compressibility and speed of sound of carbon dioxide + n-heptane binary mixture under pressure up to 70 MPa. I Experimental Measurements

Abstract

Measurements of density and speed of sound were carried out in the binary mixture comprising n-heptane with dissolved carbon dioxide at two temperatures near critical temperature (303 and 313 K) and at pressure from 10 to 70 MPa. The measurements were performed for five sample mixtures ranging from 20 to 88.5 % CO2 mol fraction. The density measurements were performed using an ANTON-PAAR vibrating U-tube densimeter whereas speed of sound measurements were based on a pulse echo technique working at 3 MHZ. Derived properties such as the isothermal and isentropic compressibilities were determined from these measurements. Finally, excess volume, excess compressibilities as well as excess speed of sound were estimated and represented as a function of CO2 content. By comparing the excess volume to the excess isothermal compressibilities and the excess speed of sound, it appeared that excess curves for derivative properties highlight large deviation from ideality in such binary system.