Development of an universal group contribution equation of state: I. Prediction of liquid densities for pure compounds with a volume translated Peng–Robinson equation of state

With a view to the development of an universal group contribution equation of state, the Peng–Robinson (PR) equation of state (EOS) has been modified to obtain a better description of saturated liquid densities for the pure compounds. A simple improved volume translation together with a temperature dependent volume correction deliver an accurate representation of this property near and far from the critical point for polar and non-polar substances. The fitted parameters have been generalized as a function of the critical compressibility factor. The results are compared with the results of the original PR and the Soave–Redlich–Kwong (SRK) EOS.