Energy analysis and exhaust emissions of a stationary engine fueled with diesel–biodiesel blends at variable loads

Compression ignition engines are widely used for transportation and power generation around the world. Even though high efficiencies are obtained for these machines, their main energy source is a non-renewable fuel. In addition to that, greenhouse gases, nitrogen oxides, particulate matter and other non-desirable substances are emitted. Biodiesel is a fuel usually proposed for Diesel engines because it is non-toxic, renewable, can be produced from different oil seeds and does not require significant modifications in the engine. This work investigates the exhaust emissions and performance of a six-cylinder direct injection Diesel engine that drives a 60-kVA electric generator at 1800 rpm. The engine was fueled with five different blends (D95B5, D75B25, D50B50, D25B75, B100) of conventional diesel oil containing up to 10 ppm of sulfur (S10 class) and biodiesel at different loads. An in-house developed system for particulate matter (PM) evaluation was created. Gaseous emissions and energy flows were evaluated. A reduction of 45% in PM emissions was observed by increasing biodiesel content from B5 to B100 at the highest load tested (27 kW). CO and NOx emissions increased slightly when compared to the mixture commercialized in Brazilian market (5% biodiesel and 95% conventional diesel). No significant variation in energy efficiency was revealed by increasing the percentage of biodiesel in the blend.