Correlation for prediction of vapor pressures of pure fluids incorporating renormalization group formulations with corresponding-states principle

Abstract

A simple correlation for predicting the vapor pressures of coal liquids between the freezing and critical points, and extending to normal fluids, has been developed on the basis of renormalization group theory and phenomenological scaling theory. The Clapeyron equation has been reduced to the integral form ▪ to represent vapor pressure using a generalized correlation developed by Sivaraman et al. (1983) for the prediction of latent heats of vaporization of normal fluids and coal-liquid model compounds. L*, the dimensionless latent heat of vaporization, andΔ z, the difference between the compressibility factors of the saturated vapor and liquid, are given by the corresponding-states correlations ▪ and ▪ based on the formulations of Pitzer et al. (1955). A simple expression for the latent heat of vaporization developed by Torquato and Stell (1982) is incorporated into this correlation. The vapor-pressure correlation has been tested successfully for 23 pure-component systems including aromatic and heterocyclic compounds often found in coal liquids and shale oil in the region 0 〈 ε = ( T c- T)/ T c 〈 0.69. The deviations in the predicted vapor pressures are in the range 0.11–5.45%.