DIESEL ENGINE PERFORMANCE AND NOX EMISSIONS FROM OXYGENATED BIOFUELS AND BLENDS WITH DIESEL FUEL

Increased pressure from federal and state agencies to improve air quality has resulted in extensive research intothe use of biofuels to reduce diesel engine emissions. Oxygenated biofuels such as biodiesel and ethanol blended with dieselfuel are biodegradable, non-toxic, renewable alternatives to imported petroleum diesel, and their use not only creates newmarkets for domestic agricultural products, but also greatly reduces particulate emissions. Unfortunately, biodiesel has beenshown to increase NOX emissions upwards of 10% compared to petroleum diesel. The objective of this investigation was toevaluate the performance and NOX emissions of selected biofuels and blends with petroleum-based diesel fuel in aturbocharged and intercooled diesel engine using a steady-state nonroad ISO 8-mode test schedule. Test fuels includedtraditional No. 2 diesel and four biofuels comprising 100% soy methyl ester biodiesel, 2% biodiesel, 10% ethanol-diesel fuel,and 5% ethanol in biodiesel. Exhaust NOX emissions were monitored with a Horiba NOX analyzer. Reductions in peak torquevarying from less than 0.5% to about 10% were measured with the test fuels and were attributed mainly to reduced energycontent. Biodiesel fuel showed a 12% increase in NOX emissions, while 2% biodiesel fuel increased emissions 2.3%. Theethanol-diesel fuel blend reduced NOX emissions by 2.7% and was highly sensitive to load, with increased temperature andNOX emissions at light load. Addition of only 5% ethanol to biodiesel suppressed NOX emissions, with only a 2.6% increaseoccurring. It was concluded that ethanol could act as an effective NOX emissions reducing additive.