R-245fa phase equilibrium line modeling method

A critical analysis of the available information on the density r ± and pressure p s of the R-245fa refrigerant on the line of phase equilibrium (LPE) has been carried out and a mathematical model of LPE has been proposed that transmits this information within the limits of its uncertainty. The LPE model was developed within the framework of the Clapeyron-Clausius and Mendeleev-Clapeyron equations, the model [2β, 1 – α] of the average diameter f d : f , where α and β are the critical indices; τ = T/T c – 1, and the equation of the «apparent» heat of vaporization, developed within the framework of the large-scale theory. It is shown that in the temperature range from T t = 171.05 K to the critical temperature T c = 427.01 K, the proposed LPE model transmits data on r ± and p s of R-245fa within the limits of their experimental uncertainty; the RSM (Root-mean square deviation) values are given, which for the most reliable data were compiled by: Feng et al. (2010), RSM (p s ) = 0,063 %; Wang et al. (2004), RSM (p s ) = 0,021 %; Semenyuk Yu. V. et al. (2006), RSM (p + ) = 0,087 %. It is shown that the combined use of the parameter, the Mendeleev–Clapeyron equation and the Clapeyron equation can significantly increase the reliability of the calculated information about the density ρ – in the vicinity of the triple point.