Steady State Diesel Engine Performance and NO_x Emissions with Selected Biofuels

Oxygenated biofuels such as biodiesel and ethanol blended with diesel fuel are biodegradable, non-toxic, renewable alternatives to imported petroleum diesel and their use not only creates new markets for domestic agricultural products, but also greatly reduces particulate emissions. Unfortunately, biodiesel has been shown to increase NO_x emissions upwards of 10% compared to petroleum diesel. The objective of this investigation was to evaluate the performance and NO_x emissions of selected biofuels in a turbocharged and intercooled diesel engine using a steady state nonroad ISO 8-Mode test schedule. Test fuels included traditional No. 2 diesel and four biofuels comprising 100% soy methyl ester biodiesel, 2% biodiesel, 10% ethanol-diesel fuel, and 5% ethanol in biodiesel. Exhaust NO_x emissions were monitored with a Horiba NOx analyzer. Biodiesel fuel showed a 12% increase in NO_x emissions while 2% biodiesel fuel increased emissions 2.3%. The ethanol-diesel fuel blend reduced emissions by 2.7% and was highly sensitive to load with increased temperature and NO_x emissions at light load. Addition of only 5% ethanol to biodiesel suppressed emissions, with only a 2.6% increase in NO_x production. It was concluded that ethanol could act as an effective NO_x emissions reducing additive.