Thermal Conductivity of CFC Alternatives: (Measurements of HCFC-123 and HFC-134a in the Liquid Phase by the Transient Hot-Wire Method)

Absolute and precise measurements have been made of the thermal conductivity of HCFC-123 and HFC-134a (CFC Alternatives) in the liquid phase with a newly developed transient hotwire apparatus for a low-temperature range. Up to the present, few experimental data about their thermal conductivity have been reported, particularly in the temperature range below 250K. The measurements have been performed on both substances in the temperature range from 193K to 353K, and in the pressure range from 1MPa to 30MPa. The accuracy of the measurements is estimated to be ±0.5%. It is found that the thermal conductivity of HCFC-123 is 12 to 15% smaller than that of CFC-11; on the other hand, in the case of HFC-134a, the thermal conductivity is about 5 to 25% larger than that of CFC-12.