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Oil is still a relevant component in the global energy matrix. However, price fluctuations, irregular production and possible shortage of oil are factors that negatively affect the world economy. Moreover, it is universal unanimity that the exploitation of oil and its derivatives causes setbacks to the environment and diminishes the population life quality. Therefore, there are studies to find natural energy sources to replace petroleum products to reduce the harmful effects caused by fossil fuels. In this work, sugarcane ethanol, widely used to supply passenger cars in Brazil, was the fuel chosen as a possible candidate for diesel replacement, even partially. To conduct the study, a reactive charge compression ignition engine fueled with diesel and ethanol was used to compare two directed injection modes: ethanol and diesel (ED) strategy (ethanol and diesel injected before top dead center (TDC)) and diesel and ethanol (DE) strategy (diesel injected before TDC and ethanol injected after TDC). In all tests in which ethanol was injected, increased ignition delay was observed. The highest efficiency was achieved using the ED injection strategy, but detonations and pressure peaks appeared. Test results also show that, using DE injection strategy, it was possible to increase the amount of ethanol injected, since no pressure peaks nor detonations appeared; however, it presented lower efficiency compared to the ED injection strategy.

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This study aims to examine experimentally the NOx emissions and the performance of a motor AGRALE M90, single cylinder, operating with diesel and biodiesel blends. The engine was linked to an electric generator, which provided 1500 W, 3000 W and 4500 W to an electrical system. The engine was tested with fuel blends containing different amounts of commercial diesel (B4) with palm biodiesel (B100). NOx emissions, as well as the specific fuel consumption of diesel, biodiesel and their mixtures were measured and analyzed. In this study, emissions of NOx have been prioritized over other pollutants by environmental issues and techniques. Air pollution by NOx causes serious respiratory problems. Furthermore, emissions of NOx enable a qualitative assessment of the combustion process. The results show that the commercial diesel has better performance in terms of energy efficiency and NOx emissions.