Evaluation of Optimal Methods for Critical Properties and Acentric Factor of Biodiesel Compounds with Their Application on Soave–Redlich–Kwong and Peng–Robinson Equations of State

In this work, different methods capable of estimating some properties of fatty acid methyl esters (FAMES) and fatty acid ethyl esters (FAEES) have been evaluated. The results for Tb indicated that the methods of Constantinou and Gani and Marrero and Gani should be applied for FAMES and FAEES, respectively. The evaluation of the methods for critical properties and acentric factor was performed by comparisons between the experimental values and output values by the Racket–Soave equation. The results indicated that different packages should be applied for FAMES, FAEES, and hydroxy-esters. For critical volume estimations, the method of Marrero and Pardillo should be used for any alkyl ester present in biodiesel. Three versions of the group contribution (GCVOL) method as well as the Rackett–Soave equation were employed to estimate pure alkyl esters and biodiesel density. All these methods showed good results in moderate temperatures, but only Rackett–Soave is indicated for high temperatures. A final validation of the chosen packages for critical properties and acentric factor was performed by applying the estimated values of these properties on Peng–Robinson and Soave–Redlich–Kwong equations of state. Additionally, a fully predictive translated volume methodology has been proposed and presented good accuracy.