Avaliação de ésteres etílicos como aditivo à gasolina

Abstract

The objective of this study was to evaluate the application of ethyl octanoate and ethyl oleate in different concentrations as gasoline additives based on characterization analyzes, consumption in Otto cycle engine and the effect of additives on fuel lubricity. Characterization analyzes were made according to ASTM and ABNT standards. The lubricity tests were carried out using a HFRR (High Frequency Reciprocating Test Rig) equipment, according ASTM D6079 standard. The analyzes of fuel consumption were performed using a Otto cycle engine four-stroke, in which the rotation was conserved at 4400 rpm and wheel power varied from 3 kW to 12 kW, to obtain hourly fuel consumption curves and brake specific fuel consumption. The analysis results of vapor pressure, distillation curve and corrosiveness were within the values required by Brasilian legislation. In relation to the rheological study, the Oswald de Waele model best fitted the experimental values of the gas + ester systems, which was also the model that best fitted the experimental data for pure gasoline data. Both esters increased the density of the fuel with increasing their concentration in gasoline. The results for heat of combustion of the obtained fuels were better than results reported in the literature for other oxygenated additives. Was found that the octane of the ethyl octanoate containing formulations was higher when compared to the formulations containing ethyl oleate. Regarding the tribological study, the WSD (wear scar diameter) values have decreased as the esters proportions have increased in the samples. The percentage of lubricant film presented values above 85% for formulations with 10% and 15% ester concentration. In addition, the increased concentration of esters in gasoline favored a significant reduction in the coefficient of friction. The consumption results of the mixtures containing gasoline and ester were similar to the consumption of type A and type C gasoline, even esters having lower heat of combustion. In relation to the brake specific fuel consumption, increasing the wheel power had a better conversion of the mass of fuel burned into energy. The results also showed that ethyl octanoate presents better characteristics to be added in gasoline when compared to ethyl oleate.