Using the group contribution method to predict the flash temperature of biodiesel and ethanol mixtures.

This article presents a novel approach to predict the flash temperature of biodiesel and ethanol mixtures using the Group Contribution Method (GCM). Expanding on the pioneering work by Liaw et al. (2003), our method employs GCM to calculate the activity coefficients of biodiesel and ethanol components in the mixture. Estimating these coefficients, crucial for accurate flash temperature prediction, involves a comprehensive analysis of composition, functional groups, and vapor-liquid equilibrium (VLE) data. For this purpose, the composition of the mixture components in biodiesel, the functional groups within each biodiesel component, the composition ratios of biodiesel and ethanol in the mixture, and the functional groups present in ethanol are considered. Given that the use of UNIQUAC and NRTL models requires estimating adjustable parameters, VLE data for ethanol and biodiesel mixtures are employed to calculate the activity coefficients. This approach not only aids in estimating these coefficients but also facilitates determining the values associated with each functional group. Flash temperature predictions for biodiesel and ethanol mixtures obtained through various models, including the ideal solution, UNIQUAC, NRTL, and our proposed GCM, are rigorously assessed. The results indicate that the GCM method outperforms the alternatives, exhibiting the lowest error with a deviation of just 1.72 K compared to deviations of 1.77 K, 1.75 K, and 1.73 K for the ideal solution, UNIQUAC, and NRTL models, respectively. This research offers a promising approach for flash point estimation in complex systems, such as biodiesel-ethanol blends, contributing to the ongoing exploration in this field.