P-V-T-x and VLE properties of difluoromethane (R32)+1,1,1,2,3,3-hexafluoropropane (R236ea) and pentafluoroethane (R125)+R236ea systems derived from isochoric measurements

Isochoric P-V-T-x measurements were performed for the difluoromethane (R32) + 1,1,1,2,3,3-hexafluoropropane (R236ea) and pentafluoroethane (R125) + 1, 1,1,2,3,3-hexafluoropropane (R236ea) systems within the 254-364 K temperatu re range and within the 111-1994 kPa pressure range. Measurements for the R 32 + R236ea system were taken for 6 different compositions and 10 expansion series, resulting in 188 data points, 101 of which were within the VLE bou ndary and 87 of which were in the superheated vapor region. Measurements fo r the R125 + R236ea system were taken for 4 different compositions and 10 e xpansion series, for a total of 213 data points, 133 of which were within t he VLE boundary and 80 of which were in the superheated vapor region. In al l, 346 data points are presented. The VLE parameters were derived from expe rimental data using a flash method and the Carnahan-Starling-De Santis equa tion of state (CSD EOS). The dew point parameters were obtained by the inte rpolation of the P-T isochoric sequence. Data from the superheated:vapor re gion were interpreted using tried and tested correlation methods for the se cond and third virial coefficients. The results, both within the VLE bounda ry and in the superheated region, revealed a mutual consistency close to th e experimental uncertainty that we evaluated.