Diesel Exhaust Emissions Using Sasol Slurry Phase Distillate Process Fuels

Transient emission tests were performed to compare emissions using fuels produced by the Sasol Slurry Phase Distillate Process, to those with US diesel fuels. A heavy-duty, four stroke, 1991 emission level diesel engine was used. Two variations of the Sasol Slurry Phase Distillate (SSPD) fuels were tested, along with fuels meeting the US 2-D and CARB specifications, as well as three blends comprising various concentrations of SSPD fuel in the 2-D fuel. It was found that the SSPD fuels produced significantly lower emissions than the 2-D and CARB fuels in all four regulated emission categories. The blended fuels generally reduced emissions in proportion to the amount of SSPD fuel in the blend. Tests were also performed at retarded injection timing settings with the SSPD fuel, which has a cetane number in excess of 70. It was found that a further reduction in NO_x emissions could be obtained, without significantly compromising particulate emissions or specific fuel consumption.