An isobaric vapor-liquid-liquid equilibrium of eight hydrocarbon systems (seven ternary and one quaternary) has been predicted by equilibrium relations and flash relations. COSMO-SAC, a variant of the COSMO-RS model has been used to calculate the activity coefficients. For the prediction of VLLE, two approaches have been adopted. A modified Rachford-Rice algorithm was used in the equilibrium approach and the Henley-Rosen algorithm for the three phase flash calculation to predict the composition via the flash approach. Overall, the average root-mean-square deviation (rmsd) in the organic phase composition using the equilibrium approach for all the systems taken together is 10.67%. The rmsd values of 7.45% in the aqueous phase and 3.26% in the vapor phase were reported via equilibrium relations. The flash algorithm when applied for two systems, namely, water + 1-propanol + di-n-propyl ether and water + 2-propanol + di-iso-propyl ether, gave an overall average rmsd in the organic phase to be 19.17%, 4.03% in the aqueous phase, and 5.84% in vapor phase.