Measurements and predictions of densities and viscosities in CO2 + hydrocarbon mixtures at high pressures and temperatures: CO2 + n-pentane and CO2 + n-hexane blends

Abstract

• Density and viscosity behavior of CO 2 + pentane or hexane is determined. • Measurements were carried out up to 100 MPa and temperatures (293.15 to 393.15) K. • The data were good correlated using Tammann-Tait and VFT models for densities and viscosities, respectively. • GERG 2008, PC-SAFT and CP-PC-SAFT are examined for modelling densities. • Viscosities were compared with REFPROP10 and MYS + CP-PC-SAFT predictions. This work reports new experimental data on densities and viscosities of (CO 2 + n -pentane) and (CO 2 + n -hexane) mixtures at high pressures and temperatures. The densities were measured by a vibrating-tube densimeter with an expanded uncertainty ( k = 2) smaller than 1.8 kg·m −3 at six isotherms (from 273.15 K to 373.15 K), twelve pressures starting at 5 MPa up to 100 MPa, and at six CO 2 molar compositions (from 0 to 0.6). The viscosities were measured by a vibrating-wire viscometer with the corresponding relative expanded uncertainty ( k = 2) smaller than 0.016 at five isotherms (from 273.15 K to 373.15 K), twelve pressures (from 5 MPa up to 100 MPa), and at two CO 2 molar compositions (0.1 and 0.3). The densities were fitted by the semiempirical Tammann-Tait equation for density data and the Vogel-Fulcher-Tammann (VFT) equation for viscosity data, respectively. The Groupe Européen de Recherches Gazières (GERG-2008) equation of state was also applied for modelling the densities. Over-all robustness and reliability of the Perturbed-Chain Statistical Association Fluid Theory (PC-SAFT) and its critical point-based modification (CP-PC-SAFT) were examined. Accuracies of the Modified Yarranton-Satyro (MYS) coupled with CP-PC-SAFT and the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10) in predicting the viscosities were evaluated.