Calculation of critical loci with an equation of state based on the significant structure model

Critical loci are shown for a recently proposed four constant noncubic equation of state based on the significant structure model. The new equation features superior liquid density representation, more meaningful molecular parameters, and fits the critical point exactly. A number of systems have been studied including those typically used in hydrocarbon processing and supercritical extraction. Comparisons are made with the cubic equation of state of Soave and its variations proposed by Peneloux. It is shown that the new equation gives comparable phase diagrams but with improved density representation. Based on the results of 58 systems, the new equation is capable of representing critical temperature to within 3.6%, critical pressure to within 3.3% and critical volume to within 7.3%, including systems containing methane.