Critical Parameters and Critical-Region ($p,\rho ,T)$ Data of trans-1,1,1,3-Tetrafluorobut-2-ene [HFO-1354mzy(E)]

Abstract

This study presents the experimental measurement of the $p\rho T$ properties and critical parameters of a low GWP type refrigerant, trans-1,1,1,3-Tetrafluorobut-2-ene (HFO-1354mzy(E)). The sample purity of the substance was 99 area %. $p \rho T$ property measurements and visual observations of the meniscus of HFO-1354mzy(E) were carried out using a metal-bellows volumometer with an optical cell. The critical temperature was determined by observation of the critical opalescence. The critical pressure and critical density were determined as the inflection point of the isothermal $p \rho T$ property data at the critical temperature. For more precise clarification of the thermodynamic surface in the vicinity of the critical point, additional $p \rho T$ property measurements were carried out on three isotherms in the supercritical region. The expanded uncertainties ($k = 2$) in the temperature, pressure, and density measurements were estimated to be less than 3 mK, 1.2 kPa, and 0.32 $\hbox {kg} \cdot \hbox {m}^{-3}$, respectively. The expanded uncertainties of the critical parameters were estimated to be less than 13 mK, 1.4 kPa, and 2.3 $\hbox {kg} \cdot \hbox {m}^{-3}$, respectively. These values are the first reported for HFO-1354mzy(E) and are necessary for the development of its equation of state in the near future.

Appendix

Measurements were carried out on isobutane (99.99 mol % purity, Takachiho Chemical Industrial Co., Ltd., Ibaraki, Japan) as a test to confirm the reliability of the measurement procedure. Figure 5 shows the observation results of the critical phenomena and the critical opalescence. The critical temperature was determined to be 407.69 K, at which the strongest critical opalescence was observed.

Fig. 5

Visual observation of the critical opalescence of isobutane

Fig. 6

Isotherm for isobutane at the critical temperature (407.69 K) and the fitted line: $\circ$, present data; –, calculated values from Eq, (1); +, the determined critical point

Fig. 7

Critical point for isobutane on $T{-}\rho$ plane and $p{-}\rho$ plane:

, present data; +, J. A. Beattie [12]; $\times$, J. F. Connolly [13]; $\blacktriangle$,R. D. Goodwin [14]; $\blacktriangledown$, J. M. Levelt Sengers [15]; $\blacklozenge$, G. Masui [4]; –, calculated values from Eq. [2]

Table 2 Literature data and obtained values of the critical parameters for isobutane

Next, we performed a series of additional $p \rho T$ property measurements at the determined critical temperature to determine the critical density and critical pressure. The obtained isothermal $p \rho T$ property data at the critical temperature were fitted to the simplified BWR equation. The results of the fitting for isobutane are shown in Fig. 6. Fitting of the simplified BWR equation to the experimental data yielded the critical parameters of $p_{c} = 3.635$ MPa, and $\rho _{\mathrm{c}} = 223.1\,\hbox {kg}\cdot \hbox {m}^{-3}$ by observing the slope and curvature of this equation as mentioned above. The critical parameters thus determined are summarized in Table 2 with other published values for isobutane. These data are illustrated on $T-\rho$ plane and $p-\rho$ plane in Fig. 7. Reasonable agreement between our values and those previously published was confirmed, indicating that the present measurement method was suitably reliable.