Temperature Dependence of the Cohesion Parameter for Calculating Binary VLE Values for Systems Containing Helium and Neon

Abstract

The temperature functions for representation of the cohesion parameter “a” of the van der Waals type cubic equations of state have been analyzed in both the subcritical and supercritical regions. The most suitable values of Ωac (=acPc/R2T c 2 ) for representation of vapour pressures of alkanes are found to be 0.4484 and 0.4254 for the Soave and the exponential functions, respectively. These results indicate that the Soave function is better suited for the Peng-Robinson equation; and the exponential functions, for the van der Waals, Redlich-Kwong and Soave-Redlich-Kwong equations. In the vapor-liquid equilibrium (VLE) calculations for systems containing helium and neon, which have very low critical temperatures, binary data have been used to determine the optimal value of Ωa (=aPc/R2T c 2 ) in the supercritical region. The temperature functions developed for these two gases have been successfully applied to VLE calculations for eight helium-containing, three neon-containing and helium-neon systems.