Flash-point estimation for binary partially miscible mixtures of flammable solvents by UNIFAC group contribution methods

The flash points of binary partially miscible mixtures of flammable solvents were estimated using the flash point prediction model of Liaw et al. (2010) [18] handling liquid phase non-ideality through UNIFAC-type models, which do not need experimentally regressed binary parameters. This predictive model was validated by the experimental data over the entire composition range of seven mixtures. The model described the experimental flash point data well, with the exception of the region close to the span of the two-liquid-phase region nearing the high boiling-point compound of the mixtures because the estimation error in such a span resulted from poor predictive capability of the modified LLE UNIFAC parameters when using VLLE models to estimate the activity coefficient. Because of nonexistence of the disadvantage of VLLE model and superior predictive capability, a model based upon the VLE UNIFAC parameters provided accurate flash point predictions for binary partially miscible mixtures of flammable solvents, as revealed by comparison between predicted and experimental data. In addition, the flash point behaviors for two different types of partially miscible mixtures of flammable solvents are discussed.