Ethane phase equilibrium line

Abstract

On the basis of the modified Clapeyron–Clausius equation, the Rykov elastic line equation, and scale theory, the line of phase ethane in the temperature range of from T = T t = 90.368 K to T = T c = 305.322 K, where T t and T c are the temperatures of triple point and critical pint, has been calculated. The equations of the elastic line, p s = p s (T), vapor, ρ – = ρ – (T), and liquid, ρ + = ρ + (T), and the branches of the saturation line have common critical exponents and critical parameters, and the average diameter f d of the saturation line in the vicinity of the critical point is described by the model [2β, 1 – α] (The Yang-Yang modified model). It is shown that this system of equations conveys experimental data on the pressure and density of saturated vapor, and the density of a saturated liquid of ethane within the uncertainty of these data with a root-mean-square error (RMS): RMS p s = 0,08 %; RMS ρ – = 0,67 %; RMS ρ + = 0,02 %. In the temperature range of from T t to T c , the tables are calculated, including the values p s , ρ – , ρ + and «apparent» heat of vaporization.