A generalized model for the thermodynamic properties of mixtures

Journal Article · Sat May 01 04:00:00 EDT 1999 · International Journal of Thermophysics

DOI:https://doi.org/10.1023/A:1022627001338· OSTI ID:20000264

Lemmon, E W; Jacobsen, R T

A mixture model explicit in Helmholtz energy has been developed which is capable of predicting thermodynamic properties of mixtures containing nitrogen, argon, oxygen, carbon dioxide, methane, ethane, propane, n-butane, i-butane, R-32, R-125, R-134a, and R-152a within the estimated accuracy of available experimental data. The Helmholtz energy of the mixture is the sum of the ideal gas contribution, the compressibility for real gas contribution, and the contribution from mixing. The contribution from mixing is given by a single generalized equation which is applied to all mixtures studied in this work. The independent variables are the density, temperature, and composition. The model may be used to calculate the thermodynamic properties of mixtures at various compositions including dew and bubble point properties and critical points. It incorporates accurate published equations of state for each pure fluid. The estimated accuracy of calculated properties is {+-}0.2% in density, {+-}0.1% in the speed of sound at pressures below 10 MPa, {+-}0.5% in the speed of sound for pressures above 10 MPa, and {+-}1% in heat capacities. In the region from 250 to 350 K at pressures up to 30 MPa, calculated densities are within {+-}0.1% for most gaseous phase mixtures. For binary mixtures where the critical point temperatures of the pure fluid constituents are within 100 K of each other, calculated bubble point pressures are generally accurate to within {+-}1 to 2%. For mixtures with critical points further apart, calculated bubble point pressures are generally accurate to within {+-}5 to 10%.

• Research Organization: Univ. of Idaho, Moscow, ID (US); National Inst. of Standards and Technology, Boulder, CO (US)
• OSTI ID: 20000264
• Journal Information: International Journal of Thermophysics, Journal Name: International Journal of Thermophysics Journal Issue: 3 Vol. 20; ISSN 0195-928X; ISSN IJTHDY
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ARGON
CARBON DIOXIDE
EQUATIONS OF STATE
HYDROCARBONS
MATERIAL SUBSTITUTION
MATHEMATICAL MODELS
MIXTURES
NITROGEN
OXYGEN
REFRIGERANTS
THERMODYNAMIC PROPERTIES