Combustion and Emission Characteristics of Fischer-Tropsch and Standard Diesel Fuel in a Single-Cylinder Diesel Engine

The emissions reduction of Fischer-Tropsch (FT) diesel fuel has been demonstrated in several recent publications in both laboratory engine testing and in-use vehicle testing. Reduced emission levels have been attributed to several chemical and physical characteristics of the FT fuels including reduced density, ultra-low sulfur levels, low aromatic content and high cetane rating. Some of the effects of these attributes on the combustion characteristics in diesel engines have only recently been documented. In this study, a Ricardo Proteous, single-cylinder, 4-stroke DI engine is instrumented for in-cylinder pressure measurements. The engine was run at several steady engine states at multiple timing conditions using both federal low sulfur and natural gas derived FT fuels. The emissions and performance data for each fuel at each steady state operating conditions were compared. The cylinder pressure data was used to determine a suite of thermodynamic indicators, which are used to help explain the emissions variations between fuels types. An attempt is made to further deepen the understanding of documented explanations regarding mechanisms for reduced emission levels in FT fuels.