CORRELATION BETWEEN TOTAL HYDROCARBON EMISSION AND ACTIVATION ENERGY OF RENEWABLE AND FOSSIL FUELS BLENDS

Resumo

Biofuels have become an alternative to replace fossil diesel to be used in diesel engine. Their behavior can be evaluated by using analytical methods as prior assessment in these engines. In this study thermogravimetry (TG) and a model-free were used to determine activation energy and the total hydrocarbon (THC) emission was determined in the OM 926 LA Euro 5 diesel engine using the European Stationary Cycle (ESC). Two types of biofuels (biodiesel from soybean and farnesane) and their blends with fossil diesel were evaluated. Farnesane is a hydrocarbon known as a renewable diesel, and is produced from sugar cane. THC emissions were correlated with the activation energy of the thermal decomposition of the fuels. From the experiments it was observed that THC emission of the farnesane is 16.67% lower than pure fossil diesel and biodiesel emits 19.30% more THC than pure fossil diesel. Activation energy of the farnesane is 82.24 kJ / mol , of the fossil diesel is 86.69 kJ / mol and of the biodiesel is 96.64 kJ / mol. From these results we could understand that the higher activation energy, the higher is the THC emissions and the presence of the oxygen in the biodiesel may be an important factor that influences such behavior. Although these results present a prediction of the fuel behavior, it is important to mention that besides the chemical characteristic of the fuel, the amount of THC in the exhaust gases depends on several factors such as the engines operating-conditions, the fuel-spray characteristics, the interaction of the fuel spray with the air in the combustion chamber.