Improving Biodiesel Emissions and Fuel Efficiency with Fuel-Specific Engine Calibration

A 2002 model year Cummins ISB 300 engine was used to examine the effects of shifting engine parameters from their stock settings on the performance of a 20% biodiesel blend (B20). The objective of this work was to determine if it is possible to use a more optimal engine calibration to eliminate the small fuel economy and NO_x emission penalties typically observed for B20 in comparison to petroleum diesel, while preserving the significant reduction in PM emissions that is also typically observed. Tests were conducted at multiple steady-state operating modes. Two engine parameters were modified: a 1° advance in fuel injection timing and a 4% exhaust gas recirculation valve position increase. For B20, the simple calibration changes yielded an average decrease in NO_x emissions of 2% with a brake-specific fuel consumption penalty of less than 1%, while still reducing PM emissions overall in comparison to B0 and the stock calibration. In comparison, the stock calibration resulted in an average 5% increase in NO_x emissions, and a 2% increase in fuel consumption with B20.