Adaptation of (h, T) Data To Calculate Some Thermodynamic Properties of SF6 on the Saturation Curve

Information is presented on the behavior of the SF6 density on the binodal in the asymptotic vicinity of the critical point 3 × 10–6 < τ < 2 × 10–4, where τ = (Tc – T)/Tc is the relative temperature, and Tc is the critical temperature. The densities of the liquid (ρl) and vapor (ρg) phases were calculated based on the experimental data of Garrabos et al. (2018) on the height h at which the meniscus is located separating the two phases of the sample in a horizontal cell of diameter d at a temperature T under the terrestrial gravity. The second component of the method was the order parameter fs(τ) in an analytical form, which meets conditions of the scaling theory (ST) of critical phenomena and is based on the (ρl, ρg, T) data of Funke et al. (1998) on SF6 in the range of 10–3 < τ < 0.3. A number of problems were formulated, including the construction of the dependences ρl(τ) and ρg(τ) those are consistent with ST and correlate with the (h, T) data at 10–6 < τ < 10–3. The relationship was studied between the (h, T) data and the functions fs(τ) and fd(τ) (fd is the average or rectilinear diameter). The temperatures dependences of ρl and ρg were constructed in the range of 10–6 < τ < 10–3 .