Reducing NOx Emissions from a Common-Rail Engine Fueled with Soybean Biodiesel
Performance and emissions of a common-rail production diesel engine fueled with soybean-derived biodiesel was investigated. The work was broken down into two categories. First, adjustment of injection timing and EGR ratio was investigated as a means to reduce NOx emissions to levels comparable with those obtained when using pure diesel fuel. Next, simultaneous reduction of NOx and soot emissions was investigated using high rates of EGR combined with late injection timings to approach the low-temperature combustion regime. Results from the first part of the study indicate that optimization of engine control parameters for use with biodiesel can be beneficial to performance and emissions. It was found that adjusting the engine's MAF setpoint table to reflect the difference in stoichiometric air-fuel ratio between diesel and biodiesel brought NOx emissions to comparable or lower levels.