RESUMEN
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.
RESUMEN
Despite well-known corrosion inhibition behavior of cathodic protection (CP) system, this process might be a potential hazard to surrounding ecosystem resulted mostly from continuous electrical current which is applied to the adjacent environment and metallic anode dissolution as well. In this research, deepwater CP wells at different locations of Golestan province, Iran, were taken into consideration to evaluate the impact of these protective systems on underground waters from viewpoint of chemical and physicochemical characteristics resulted from anode dissolution. For this purpose, concentration of metallic constituents of the anode as well as the amount of pH, total dissolved solids (TDS), electrical conductivity (EC), and total hardness were determined. On the basis of obtained results, the concentration of Mn, Cr, and Fe in CP well located nearby an industrial district (i.e., 0.087, 0.475, and 8.5 mg/L, respectively) was higher than both WHO and USEPA standards. This fact can be resulted from the position where the well was dug as well as the CP anode dissolution within the deep CP water wells. PRACTITIONER POINTS: The impact of impressed current cathodic protection (ICCP) system on chemical and physicochemical characteristics of underground water has been evaluated. Anode dissolution of ICCP systems influences the water characteristics nearby the anodes. Despite low dissolution rate of high silicon cast iron anodes, their long-term utilization might be harmful for adjacent ecosystem. The amount of heavy metals in underground waters was demonstrated to be influenced by the employment of ICCP system. Both anode dissolution and the geological properties of the Earth`s crust surrounding the wellbore might be responsible for significant increase of heavy metals concentration.