Thermodynamic properties of the trans-1,3,3,3-tetrafluoropropene refrigerant: a method for constructing the equation of state and the tabulated data

This study discusses the transition toward the use of environmentally friendly refrigerants in low-temperature technology. It also considers a new environmentally friendly fourth-generation refrigerant trans‑1,3,3,3-tetrafluoropropene R1234ze(E) as an alternative to the R134a refrigerant common in chillers and heat pumps, as well as the R22 refrigerant in air conditioning systems. A technique has been developed for constructing a unified fundamental equation on the states of liquid and gas for trans‑1,3,3,3-tetrafluoropropene. Around the critical point, the proposed fundamental equation satisfies the requirements of the scale theory for asymmetric systems, and in the region of a rarefied gas, it is reduced to the virial equation of state. Based on this fundamental equation, tables of standard reference data on pressure, density, enthalpy, isobaric and isochoric heat capacities, entropy, heat of vaporization, and sound velocity of trans‑1,3,3,3-tetrafluoropropene in the region of state parameters in the temperature ranges of 169–420 K and pressure of 0.1–100 MPa were calculated. Several statistical characteristics have been calculated, namely, absolute mean deviation, systematic deviation, standard deviation, and root mean square deviation, characterizing the accuracy of the proposed fundamental equation in describing the experimental values of the equilibrium properties obtained in recognized international thermophysical centers. Evidently, the values of these statistical characteristics are significantly lesser than those of the corresponding characteristics of the international fundamental equations of state, provided in the literature, when describing the thermal and caloric experimental data of trans‑1,3,3,3-tetrafluoropropene. The estimated expanded uncertainties of the tabulated data based on the proposed fundamental equation were 0.26% for density, 0.57% for pressure, 1.7% and 1.2% for isochoric and isobaric heat capacities, respectively, and 0.38% for sound velocity. The results suggest that the proposed unified fundamental equation of state adequately conveys the thermodynamic characteristics of trans‑1,3,3,3-tetrafluoropropene over the specified range of temperatures and pressures.