Thermal Conductivity of 1,1-Difluoroethane (HFC-152a)

Thermal conductivity measurements were performed on 1,1-difluoroethane (HFC-152a) using the polarized transient hot-wire technique in the temperature range of 214 to 294 K and at pressures up to 19 MPa. This technique was used previously for measurements on other halocarbons along the saturation line and in the compressed liquid phase. No dependence of the polarization voltage was found for the thermal conductivity values, demonstrating that the technique was used with success. Also, no influence of heat transfer by radiation or convection was detected, in all the range of densities studied. The samples were supplied with stated purities greater than 99.9%. The reproducibility of the experiments was found to be 0.03%, while the total uncertainty is estimated to be 0.5%. The experimental data were compared with data from other sources. Values for the thermal conductivity along the saturation line for several temperatures were achieved by extrapolating the high-pressure data to the saturation density for each isotherm. The data obtained were also correlated using a modification of the van der Waals model (smooth hard spheres) with an uncertainty of 1.1%, at a 95% confidence level.