Improving Biodiesel Blended Fuels: Overcoming the NOx Penalty and Enhancing the Engine's Regulated Emissions Profile

Emulsified B20 fuel containing 6.5% mass water has been shown to fully eliminate the NOx penalty associated with diesel blends containing biodiesel. The soybean biodiesel fuel used in this study showed a 6% increase in NOx when formulated as B20 blend in a 2004 Tier 2 Cummins QSM11C engine. This is about twice as high as the average for B20 fuels on account of the higher degree of unsaturation in the fatty acid backbone of soybean oil. In conjunction with a diesel oxidation catalyst (DOC) the emulsified fuel gave impressive reductions in HC, CO and PM with no increase in NOx making emulsified biodiesel fuels with or without a DOC and attractive option for heavy duty applications.