A thermodynamic equation of state for pentafluoroethane (R-125)

H. Sunaga, R. Tillner-Roth, H. Sato, K. Watanabe

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


We developed a fundamental equation of state for pentafluoroethane (R-125, CHF2CF3) which is represented in terms of a non-dimensional Helmholtz free energy. The equation has been established on the basis of selected measurements of the pressure-density-temperature relation, speed of sound, heat capacities, and saturation properties. Linear and non-linear regression analysis was employed to determine the functional form and the numerical parameters. The equation represents all the thermodynamic properties of R-125 in the liquid and gaseous phases for temperatures between the triple point and 470 K, and pressures up to 35 MPa. The uncertainties are estimated to be about ±0.05% or 0.1 kPa for the vapor pressure, ±0.05% for the liquid and vapor densities, about ±1% for the isobaric and isochoric heat capacities in the liquid, and ±0.5% or ±0.02% for the speed of sound in the liquid and vapor, respectively.

Original languageEnglish
Pages (from-to)1623-1635
Number of pages13
JournalInternational Journal of Thermophysics
Issue number6
Publication statusPublished - 1998 Nov


  • Equation of state
  • HFCs
  • Pentafluoroethane
  • R-125
  • Refrigerant
  • Thermodynamic properties

ASJC Scopus subject areas

  • Condensed Matter Physics


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