Effects of Advanced Fuels on the Particulate and NOx Emissions from an Optimized Light-Duty CIDI Engine 2001-01-0148

A compression ignition direct injection (CIDI) engine was used to evaluate the engine-out emissions from four advanced CIDI fuels that define a broad range of properties. The fuels include a market-averaged California fuel (designated CARB) to serve as a benchmark, a petroleum-based low sulfur, low aromatic hydrocracked fuel (LSHC), the LSHC fuel blended with 15% dimethoxy methane (DMM15), and a neat Fischer-Tropsch fuel (FT100).

Engine-out particulate matter (PM), oxides of nitrogen (NOx), and performance data were collected at 5 steady-state operating conditions. The engine calibration was optimized for each fuel and operating condition. Fuel injection timing was optimized for best fuel economy and the injection pressure was optimized for minimum smoke. The PM-NOx trade-off for EGR dilution was established for each fuel and operating condition with the optimum injection timing and pressure.

Modal averaged mass emission results were computed for each fuel using a weighted combination of the data from each of the 5 operating conditions. Weighted results simplified the relative emission comparisons and improved the confidence in the statistical analysis. Dunnett statistical techniques, for multiple-comparisons to a benchmark, were applied to the weighted results. Compared to the CARB fuel, the engine-out Total PM increased by 10% for LSHC, decreased by 24% for DMM15 and decreased by 31% for FT100 for the engine operating at conventional EGR rates. When operating the engine at the maximum EGR rates, the engine-out Total PM increased by 25% for LSHC; decreased by 16% for DMM15 and decreased by 15% for FT100. Engine-out NOx was slightly lower for the advanced fuels.