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Five different diesel fuel feedstocks were processed to two levels of aromatic (0.05 sulfur, and then 10 percent) content. These materials were distilled into 6 to 8 narrow boiling range fractions that were each characterized in terms of the properties and composition. The fractions were also tested at five different speed load conditions in a single cylinder engine where high speed combustion data and emissions measurements were obtained. Linear regression analysis was used to develop relationships between the properties and composition, and the combustion and emissions characteristics as determined in the engine. The results are presented in the form of the regression equations and discussed in terms of the relative importance of the various properties in controlling the combustion and emissions characteristics. The results of these analysis confirm the importance of aromatic content on the cetane number, the smoke and the NOx emissions.

A series of coal-derived test fuels for compression ignition engines was prepared from Exxon Donor Solvent middle distillate, a representative alternative feedstock made from coal. This series will be used in experimental work for the Alternative Fuels Utilization Program of the U.S. Department of Energy. Processing included caustic extraction of phenolic compounds, hydrogenation to remove remaining heteroatoms (N, O, and S) and increase hydrogen content (from 10.9 M%), and nitrogen stripping to remove residual by-product gases and control the flash point. Operations at three degrees of hydrogenation severity yielded products with 11.9, 12.7, and 13.1 M% hydrogen. Characterizations included standard ASTM tests, instrumental methods for chemical composition (MS, NMR), and engine tests of ignition quality.