A Molecular-Based Equation of State for Vapour-liquid Equilibrium of Pure Substances

A semi-empirical equation of state has been studied for modelling vapour-liquid data of pure substances. The specific molecular based equation of state is employed here as basis because of its mathematical simplicity. The semi-empirical extension has been accomplished to real fluids by correlating the density dependence of the attraction term to vapour liquid data of a reference fluid. The resulting attraction term is mathematically relatively simple and fulfills the topological requirements given by the physical background. With this model vapour-liquid equilibrium data for pure substances have been correlated. The investigated systems include n-alkanes, 1-alkanols, acetone and carbon dioxide. The results are compared with those obtained by PR (Peng-Robinson), SRK (Soave-Redlich-Kwon) and RM (Riazi-Mansoori) equations of state.