Compressed liquid density and speed of sound measurements and correlation of the binary mixture {carbon dioxide (CO 2 ) + 1,1-difluoroethene (R1132a)} at temperatures from 220 K to 350 K

The blend of carbon dioxide and R1132a has been suggested as a feasible alternative to R23 in lowtemperature devices. In this work, we present new experimental data for compressed-liquid density, vapour density and compressed-liquid speed of sound for the binary system CO2 + R1132a by means of a two-sinker densimeter and a pulse-echo-type instrument, respectively. The measurements cover the temperature range of 220 K to 350 K with pressures to 30 MPa for density; the speed of sound measurements cover the range 230 K to 350 K with pressures to 55 MPa; for both properties two mixture compositions were measured. Finally, we present an Equation of State (EoS) correlation for the experimental data based on a Helmholtz free energy model, which shows a good agreement with the measurements. The mixture strongly absorbed the sound pulse, and the usual dual-path analysis was not possible; thus, we developed a method using only the short-path signal.