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The isochoric specific heat capacity (c V ) of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and mole fraction x = 0.489 HFO-1234ze(E) + (1 − x) = 0.511 CO2 in the liquid phase were measured with a twin-cell type adiabatic calorimeter. The sample purity of HFO-1234ze(E) and CO2 was certified to have a minimum purity of 0.9996 mole fraction and 0.99999 mole fraction respectively by gas chromatographic analysis. The measurements were obtained for temperatures ranging from (270 to 425) K and at pressures up to 30 MPa. Temperatures were measured with a platinum resistance thermometer on the bottom of each cell and were reported based on the International Temperature Scale of 1990 (ITS-90). Sample pressures were measured with a quartz crystal transducer. Densities were calculated from the volume of the calorimeter cell and the sample mass. The expanded uncertainty (with a coverage factor k = 2) of temperature measurements is 13 mK and 8 kPa for pressure measurements. The expanded relative uncertainty of density is 0.16 %. As a result, the experimental expanded relative uncertainty of the isochoric specific heat capacity (c V ) is estimated to be from 3.8 % to 4.6 % in the liquid phase. The c V measurements were almost the same as the values calculated from the proposed equations of state except near the critical isochore.

The isobaric specific heat capacity (c p ) was measured for R-143a (1,1,1-trifluoroethane) in the gas phase. Ten measurements for R-143a were obtained at temperatures from 311 to 343 K and at pressures from 1.6 to 2.4 MPa. Some of them are close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less 25 mK, and that of the pressure measurements is less 8 kPa. The expanded uncertainty for c p is estimated to range from 9 to 32 J·kg −1 ·K −1 . Also, the experimental data were evaluated with available equations of state.

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