Analysis of the phase equilibrium line developed on the basis of the Clapeyron–Clausius equation and various models of the mean diameter

DOI: 10.17586/1606-4313-2018-17-4-28-34
UDC 536.71

Analysis of the phase equilibrium line developed on the basis of the Clapeyron–Clausius equation and various models of the mean diameter

Rykov S.V. , Kudryavtseva I.V. , Rykov V.A.

For citation: Rykov S.V., Kudryavtseva I.V., Rykov V.A. Analysis of the phase equilibrium line developed on the basis of the Clapeyron–Clausius equation and various models of the mean diameter. Vestnik Mezhdunarodnoi akademii kholoda. 2018. No 4. p.28-34.

Abstract
We set the task of conducting a comparative analysis of various models of the mean diameter for the saturation line based on a system of mutually consistent equations for the steam branch of the saturation line, the liquid branch of the saturation line, and the elasticity line. In our methodical approach the Clapeyron-Clausius equation and the heat of vaporization are involved. We have elaborated a structure that is related to these models and meets the requirements of the scaling theory of critical phenomena. Experimental data on the density of saturated liquid, saturated vapor density, and saturated vapor pressure of sulfur hexafluoride are chosen to calculate the adjustable coefficients of these models. Various models of the average diameter (the Yang-Yang model, the Wegner model, and the "three beta" model) are compared. The comparison demonstarets that the "three beta" modeldescribe the experimental data on the thermal properties of  sulfur hexafluoride at the phase equilibrium curve obtained in the temperature range from the triple point to the critical point most satisfactorily (within the experimental errors).

Keywords: critical point; saturation line; density; pressure; the mean diameter; the Wegner model; the Yang-Yang model; the Clapeyron-Clausius equation.


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