THE PREDICTION OF PURE COMPONENT PROPERTIES IN THE SUBCRITICAL RANGE USING AN EQUATION OF STATE

A method is proposed for predicting vapor pressures, liquid densities and vaporization enthalpies of pure compounds in a wide temperature ra nge between the triple point and the critical point. The method relies on the application of a previously proposed multicomponent equation o f state which is based on well known properties of pure components and universal behavior of fluids. Simple rules are given for the calculat ion of all eight constants of the chosen equation of state which requi res as input data the critical point and the normal boiling temperatur e only. The reliability of the new procedure is discussed on the basis of results obtained by predicting the properties of several well stud ied compounds belonging to the following classes: hydrocarbons, alcoho ls, acids and polar compounds not strongly associated. The method comp ares favorably with the Riedel equation for predicting the vapor press ures and with the Rackett equation for predicting the orthobaric densi ties. However, it only gives semi-quantitative results for the vaporiz ation enthalpies of the C5+ compounds. The method appears less sensiti ve to the inaccuracies of the critical values than literature methods.