ABSTRACT
Quasicontinuous PρT data of CO(2), ethane, propane, and the [CO(2) + ethane] mixture have been determined along subcritical, critical, and supercritical regions. These data have been used to develop the optimal experimental method and to determine the precision of the results obtained when using an Anton Paar DMA HPM vibrating-tube densimeter. A comparison with data from reference EoS and other authors confirm the quality of our experimental setup, its calibration, and testing. For pure compounds, the value of the mean relative deviation is MRD(ρ) = 0.05% for the liquid phase and for the extended critical and supercritical region. For binary mixtures the mean relative deviation is MRD(ρ) = 0.70% in the range up to 20 MPa and MRD(ρ) = 0.20% in the range up to 70 MPa. The number of experimental points measured and their just quality have enable us to determine some derivated properties with satisfactory precision; isothermal compressibilities, κ(T), have been calculated for CO(2) and ethane (MRD(κ(T)) = 1.5%), isobaric expasion coefficients, α(P), and internal pressures, π(i), for CO(2) (MRD(α(P)) = 5% and MRD(π(i)) = 7%) and ethane (MRD(α(P)) = 7.5% and MRD(π(i)) = 8%). An in-depth discussion is presented on the behavior of the properties obtained along subcritical, critical, and supercritical regions. In addition, PuT values have been determined for water and compressed ethane from 273.19 to 463.26 K up to pressures of 190.0 MPa, using a device based on a 5 MHz pulsed ultrasonic system (MRD(u) = 0.1%). With these data we have calibrated the apparatus and have verified the adequacy of the operation with normal liquids as well as with some compressed gases. From density and speed of sound data of ethane, isentropic compressibilities, κ(s), have been obtained, and from these and our values for κ(T) and α(P), isobaric heat capacities, C(p), have been calculated with MRD(C(p)) = 3%, wich is within that of the EoS.
ABSTRACT
The volumetric behavior for the {CO2 (1) + C2H6 (2)} system has been studied. Density measurements of {CO2 (1) + C2H6 (2)} binary mixtures at 293.15 and 308.15 K, at several pressures and compositions, and density measurements for infinitely dilute solutions at 304.21 and 308.15 K 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, s(rho)(r), was estimated to be better than 0.1%, and the uncertainties in temperature and pressure were estimated as +/-0.01 K and +/-0.001 MPa, respectively. In the experimental setup, an uncertainty in the mole fraction of u(x(j)) = +/-0.0015 has been achieved. Other properties related to P-rho-T-x data such as the compressibility factor, Z, excess molar volumes, V(m)(E), and partial molar volumes, V(i) and V(i)(infinity) have been calculated. The volumetric behavior has been compared with literature data and with that obtained from the PC-SAFT EoS rescaled parameters; these parameters have been obtained from our previous experimental values for the critical temperature and pressure of pure compounds. The value for the Krichevskii parameter, A(Kr), was obtained from the experimental density data for infinitely dilute solutions measured in this work, and it has been compared with that obtained from critical properties. Structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept.
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
