Diesel Engine Emissions and Performance Optimization for Neat GTL Fuel 2008-01-1405

The emissions reduction potential of neat GTL (Gas to Liquids: Fischer-Tropsch synthetic gas-oil derived from natural gas) fuels has been preliminarily evaluated by three different latest-generation diesel engines with different displacements. In addition, differences in combustion phenomena between the GTL fuels and baseline diesel fuel have been observed by means of a single cylinder engine with optical access. From these findings, one of the engines has been modified to improve both exhaust emissions and fuel consumption simultaneously, assuming the use of neat GTL fuels. The conversion efficiency of the NOx (oxides of nitrogen) reduction catalyst has also been improved. The desirable properties of GTL fuels for diesel combustion, namely high Cetane number and absence of PAH (Poly-Aromatic Hydrocarbons) contents have been fully utilized to enhance the conventional diesel combustion limits to show the possibility to meet the anticipated future emission regulations without any deterioration of fuel economy. The results of this study indicate not only the superior emission characteristics of the GTL fuels, but also evidence that higher EGR (Exhaust Gas Recirculation) and lower excess air ratio will be a key concept of both engine and aftertreatment optimization.