ISOBARIC HEAT-CAPACITY FOR LIQUID 1-CHLORO-1,1-DIFLUOROETHANE AND 1,1-DIFLUOROETHANE

The isobaric heat capacities (C(P)) for liquid 1-chloro-1,1-difluoroethane (HCFC-142b) and 1,1-difluoroethane (HFC-152a) have been measured by means of flow calorimetry. For HCFC-142b, 31 C(P) values have been measured at temperatures from 276 to 350 K and pressures from 1.0 to 3.0 MPa. For HFC-152a, 36 C(P) have been measured at temperatures from 276 to 360 K and pressures from 1.0 to 3.2 MPa. The uncertainties are estimated as +/-13 mK in temperature, +/-3 kPa in pressure, and +/-0.4% for most of the C(P) measurements. The purity of samples used for both HCFC-142 band HFC-152a measurements was 99.95 mol%. Correlations of liquid C(P) as a function of temperature and pressure have been developed for both refrigerants on the basis of the measurements.