Performance and emissions of an engine operating with the direct injection of diesel, biodiesel, and wet ethanol blends

Abstract

This research evaluates the performance and pollutant emissions of a motor generator set equipped with a compression ignition engine, adapted to operate with the direct injection of ethanol and diesel oil. Fuel injection was conducted with separate systems. The experiments were carried out with power loads varying from 15 kW to 37.5 kW, an ethanol injection angle of 40o crank angle degree (CAD) before the top dead center (BTDC), and a 23o CAD BTDC diesel injection angle. The diesel fuel was replaced with ethanol mass percentages ranging from 52% to 59%, with the ethanol being over-hydrated from 7% to 30% by the mass of water. The emissions and performance exhibited different behaviors, varying according to the power loads and hydration contents. The results showed significant reductions in the emissions of nitrogen oxides (NOx) and smoke opacity for all the fuel mixtures used. An increase of approximately 5% in engine fuel conversion efficiency was observed when operating with ethanol blends at higher power loads. The occurrence of an ignition delay with the use of wet ethanol did not vary significantly with the amount of water mass, but it did vary with the operating load. It was also found that a higher volume of water in the fuel promoted an increase in the in-cylinder pressure at higher loads. These results suggest that the use of a fuel mixture containing diesel oil and wet ethanol blends, directly injected by separate systems, can favor the reduction of emissions and reliance on petroleum-based fuels. This could potentially lead to a cost reduction in the production of this renewable fuel, without compromising the performance of the engine.