Vapour Pressure Measurements and Correlations for 1,1-Difluoroethene (R-1132a) at 240–296 K using a Newly Developed Isochoric Apparatus

A new isochoric apparatus was developed for measuring PvT properties of refrigerants from 240 K to 410 K. This temperature range extends measurements below ambient (~ 300 K) and overlaps with the range of other isochoric apparatuses in NEXT-RP centre of I2CNER, Kyushu University. PvT properties of four refrigerants (1,1,1,2-tetrafluoroethane, R-134a; pentafluoroethane, R-125; trifluoromethane, R-23 and 2,3,3,3-tetrafluoropropene, R-1234yf) were measured for the inner volume calculation and validation exercise. Vapour pressures of 1,1-difluoroethene (R-1132a) were measured between 240 K and 296 K (14 data points). All property measurements were conducted for heating up and cooling down phases. The expanded uncertainty values of temperature, pressure and density using the new isochoric apparatus are U(T) = 10 mK, U(p) = 1 kPa and U_r(ρ) = 0.002, respectively, where the coverage of 2 was adopted for 95% confident levels. The measured vapour pressures were fitted using Wagner-type and Antoine-type equations and compared with the published data.