Thermodynamics Research Center / ThermoML | International Journal of Thermophysics

Isochoric Heat Capacity of CO2+n-Decane Mixtures in the Critical Region

Polikhronidi, N. G., Batyrova, R. G., Abdulagatov, I. M., Stepanov, G. V.
Int. J. Thermophys. 2006, 27, 3, 729-759
ABSTRACT
The isochoric heat capacity of two binary (CO2 +n-decane) mixtures (0.095 and 0.178 mole fraction of n-decane) have been measured with a hightemperature, high-pressure, nearly constant volume adiabatic calorimeter. Measurements were made at nineteen near-critical liquid and vapor densities between 87 and 658 kg *m3 for the composition of 0.095 mole fraction n-decane and at nine densities between 83 and 458 kg * m3 for the composition of 0.178 mole fraction n-decane. The range of temperatures was 295 to 568 K. These temperature and density ranges include near- and supercritical regions. The measurements were performed in both one- and two-phase regions including the vapor + liquid coexistence curve. The uncertainty of the heat- capacity measurements is estimated to be 2% (coverage factor k = 2). The uncertainty in temperature is 15 mK, and that for density measurements is 0.06%. The liquid and vapor one-(C_V 1,C__ V 1) and two-phase (C_V 2,C__ V 2) isochoric heat capacities, temperatures (TS), and densities (S) at saturation were measured by using the well-established method of quasi-static thermograms for each filling density. The critical temperatures (TC), the critical densities (C), and the critical pressure (PC) for the CO2 + n-decane mixtures were extracted from the isochoric heat-capacity measurements on the coexistence curve. The observed isochoric heat capacity along the critical isochore of the CO2 +n-decane mixture exhibits a renormalization of the critical behavior of CVX typical for mixtures. The values of the characteristic parameters (K1, K2), temperatures (1, 2), and the characteristic density differences (_-1,_-2) were estimated for the CO2+n-decane mixture by using the critical-curve data and the theory of critical phenomena in binary mixtures. The ranges of conditions were defined on the T-x plane for the critical isochore and the -x plane for the critical isotherm, for which we observed renormalization of the critical behavior for the isochoric heat capacity.
Compounds
# Formula Name
1 C10H22 decane
2 CO2 carbon dioxide
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • 2
  • Critical pressure, kPa ; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • Derived from isochoric Cv measurments
  • 2
  • POMD
  • 1
  • 2
  • Critical temperature, K ; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • Derived from isochoric Cv measurments
  • 2
  • POMD
  • 1
  • 2
  • Critical density, kg/m3 ; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • Derived from isochoric Cv measurments
  • 2
  • POMD
  • 1
  • 2
  • Molar heat capacity at constant volume, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • iso
  • 7
  • POMD
  • 1
  • 2
  • Mass density, kg/m3 ; Liquid
  • Temperature, K; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • Derived from isochoric Cv measurments
  • 7
  • POMD
  • 1
  • 2
  • Mass density, kg/m3 ; Gas
  • Temperature, K; Gas
  • Mole fraction - 1; Gas
  • Gas
  • Liquid
  • Derived from isochoric Cv measurments
  • 24
  • POMD
  • 1
  • 2
  • Molar heat capacity at constant volume, J/K/mol ; Fluid (supercritical or subcritical phases)
  • Temperature, K; Fluid (supercritical or subcritical phases)
  • Mass density, kg/m3; Fluid (supercritical or subcritical phases)
  • Mole fraction - 1; Fluid (supercritical or subcritical phases)
  • Fluid (supercritical or subcritical phases)
  • Isochoric Heat Capacity Apparatus
  • 236
  • POMD
  • 1
  • 2
  • Molar heat capacity at constant volume, J/K/mol ; Gas
  • Mass density, kg/m3; Gas
  • Temperature, K; Gas
  • Mole fraction - 1; Gas
  • Gas
  • Derived from isochoric Cv measurments
  • 24