论文信息 - Equations of state for the thermodynamic properties of R32 (difluoromethane) and R125 (pentafluoroethane)

Equations of state for the thermodynamic properties of R32 (difluoromethane) and R125 (pentafluoroethane)

Thermodynamic properties of difluoromethane (R32) and pentafluoroethane (R125) are expressed in terms of 32-term modified Benedict-Webb-Rubin (MBWR) equations of state. For each refrigerant, coefficients are reported for the MBWR equation and for ancillary equations used to fit the ideal-gas heat capacity and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined with a multiproperty fit that used the following types of experimental data: PVT: isochoric, isobaric, and saturated-liquid heal capacities; second virial coefficients; and properties at coexistence. The respective equations of stale accurately represent experimental data from 160 to 393 K and pressures to 35 MPa for R32 and from 174 to 448 K and pressures to 68 MPa for R125 with the exception of the critical regions. Both equations give reasonable results upon extrapolation to 500 K and 60 MPa. Comparisons between predicted and experimental values are presented.

M. McLinden | S. L. Outcalt | M. O. McLinden | S. Outcalt

[1] G. M. Wilson,et al. Thermophysical properties of HFC-125 , 1992 .

[2] Richard T. Jacobsen,et al. Thermodynamic Properties of Nitrogen Including Liquid and Vapor Phases from 63K to 2000K with Pressures to 10,000 Bar, , 1973 .

[3] L. J. V. Poolen,et al. Coexisting densities, vapor pressures and critical densities of refrigerants R-32 and R-152a, at 300-385 K , 1993 .

[4] J. G. Hust,et al. Curve-fitting techniques and applications to thermodynamics , 1967 .

[5] G. Morrison,et al. Compressed Liquid Densities and Saturation Densities of Pentafluoroethane (R125) , 1992 .

[6] R. D. Mccarty,et al. Determination of Thermodynamic Properties from the Experimental p–V–T Relationships , 1975 .

[7] G. Morrison,et al. Thermodynamic Properties of Difluoromethane , 1994 .

[8] A. M. Silva,et al. Measurements of the Vapor Pressures of Difluoromethane, 1-Chloro-1,2,2,2-tetrafluoroethane, and Pentafluoroethane , 1994 .

[9] M. Moldover,et al. Alternative refrigerants difluoromethane and pentafluoroethane: critical temperature, refractive index, surface tension, and estimates of liquid, vapor, and critical densities , 1994 .