Molar heat capacity at constant volume of 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) from the triple-point temperature to 345 k at pressure to 35 MPa

Journal Article · Tue Sep 01 04:00:00 EDT 1998 · International Journal of Thermophysics

DOI:https://doi.org/10.1023/A:1021983502589· OSTI ID:305482

Magee, J W ^[1]

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1. National Inst. of Standards and Technology, Boulder, CO (United States)

Molar heat capacities at constant volume (C{sub v}) of 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) have been measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase (C{sub v}{sup (2)}), saturated-liquid (C{sub {sigma}} or C{sub x}{prime}), and single-phase (C{sub v}) molar heat capacities. The C{sub {sigma}} data were used to estimate vapor pressures for values less than 105 kPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature and the enthalpy of fusion were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded relative uncertainty (with a coverage factor k = 2 and thus a two-standard deviation estimate) for C{sub v} is estimated to be 0.7%, for C{sub v}{sup (2)} it is 0.5%, and for C{sub {sigma}} it is 0.7%.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-91CE23810
• OSTI ID: 305482
• Journal Information: International Journal of Thermophysics, Journal Name: International Journal of Thermophysics Journal Issue: 5 Vol. 19; ISSN IJTHDY; ISSN 0195-928X
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
FLUORINATED ALIPHATIC HYDROCARBONS
MATERIAL SUBSTITUTION
REFRIGERANTS
SPECIFIC HEAT
TRANSITION HEAT
TRIPLE POINT
VAPOR PRESSURE