Analytical Representations of the Phase Equilibrium Curve of the Water–Vapor System

Abstract

A brief critical analysis of the theoretical P(T) liquid–vapor phase equilibrium curves is given. Based on the Clapeyron–Clausius equation and data on the heat capacity of water, a two-parameter expression of the P(T) curve is obtained for water in the temperature range from the triple point to 389 K. The parameters of the P(T) curve are determined from data on the pressure and heat of evaporation of water at the triple point. The accuracy of the P(T) function is comparable to the actual accuracy of standard thermodynamic tables for water and water vapor.