Critical Properties and High-Pressure Volumetric Behavior of the Carbon Dioxide + Propane System at <i>T</i> = 308.15 K. Krichevskii Function and Related Thermodynamic Properties

Abstract

Critical properties and volumetric behavior for the {CO2(1)+C3H8(2)} system have been studied. The critical locus was measured with a flow apparatus and detected by critical opalescence. For the mixtures, repeatabilities in critical temperature and pressure are rTc<or=0.15 K and rPc<or=0.013 MPa, respectively, and the confidence intervals calculated are c.i.(Tc)<0.32 K and c.i.(Pc)<0.034 MPa. The value for the Krichevskii parameter, AKr=-4.12 MPa, was obtained from the experimental critical data in this work. Additionally, the density measurements of 15 {CO2(1)+C3H8(2)} binary mixtures at 308.15 K and pressures up to 20 MPa were carried out using an Anton Paar DMA 512-P vibrating-tube densimeter calibrated with the forced path mechanical calibration model. The mean relative standard deviation of density, srhor, was estimated to be better than 0.1%, and the uncertainties in temperature and pressure are +/-0.01 K and +/-0.001 MPa, respectively. In the experimental setup, an uncertainty in the mole fraction, u(xj)=+/-0.0015, has been achieved. Other properties related to P-rho-T-x data such as saturated densities, rhoL and rhoV, compressibility factor, Z, excess molar volumes,VmE, and partial molar volumes, Vi, have been calculated. Structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept. Both the critical and volumetric behavior have been compared with literature data and with those obtained from the PC-SAFT and Patel-Teja equations of state.