COMBUSTION CHARACTERISTICS OF COMPRESSION IGNITION ENGINE FUEL COMPONENTS

Combustion characteristics of pure hydrocarbons and refinery-type fuel components have been investigated as part of a broad-scope fuel program now in progress at the Ordnance Fuels and Lubricants Research Laboratory. The CFR and CLR diesel engines were used for this investigation and multicylinder verification of the data was obtained with a GM 3-71 engine. Results obtained with about 50 pure hydrocarbons illustrated the importance of molecular structure on compression ignition combustion. Through use of the laboratory engines, under conditions discussed in this paper, cetane number was shown to be the most important property for predicting relative combustion performance of all types of fuel components. Ignition delay correlated well with cetane number, but rates of pressure rise and maximum combustion pressures to some extent, depended, upon the specific engine combustion system involved. Varying intake air temperature over the range of 150 -0 F did not change the relative ranking of materials investigated; however, at a constant compression ratio low intake air temperatures caused differences among fuels to be emphasized because of borderline conditions.