Isochoric p-p-T measurements on difluoromethane (R32) from 142 to 396K and pentafluoroethane (R125) from 178 to 398 K at pressures to 35 MPa
- National Inst. of Standards and Technology, Boulder, CO (United States)
The p-{rho}-T relationships were measured for difluoromethane (R32) and pentafluorethane (R125) by an isochoric method with gravimetric determinations of the amount of substance. Temperatures ranged from 142 to 396 K for R32 and from 178 to 398 K for R125, while pressures were up to 35 MPa. Measurements were conducted on compressed liquid samples. Determinations of vapor pressures were made for each substance. The author used vapor pressure data and the p-{rho}-T data to estimate saturated liquid densities by extrapolating each isochore to the vapor pressure, and determining the temperature and density at the intersection. Published p-{rho}-T data are in good agreement with this study. For the p-{rho}-T apparatus, the uncertainty of the temperature is {plus_minus}0.03 K, and for pressure it is {plus_minus}0.01% at p>3 MPa and {plus_minus}0.05% at p<3 MPa. The principal source of uncertainty is the cell volume (28.5193 cm{sup 3} at 0K and 0 MPa), which has a standard uncertainty of {plus_minus}0.003 cm{sup 3}. When all components of experimental uncertainty are considered, the expanded uncertainty (at the two-sigma level) of the density measurements is estimated to be 0.05%.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 376927
- Journal Information:
- International Journal of Thermophysics, Journal Name: International Journal of Thermophysics Journal Issue: 4 Vol. 17; ISSN IJTHDY; ISSN 0195-928X
- Country of Publication:
- United States
- Language:
- English
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