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A combustion-based analytical method, initially developed by the Southwest Research Institute (SwRI) referred to as the Constant Volume Combustion Apparatus (CVCA), has been further researched/developed by an SwRI licensee (Advanced Engine Technology Ltd.) as an Ignition Quality Tester (IQT) for laboratories and refineries. The IQT software/hardware system permits rapid and precise determination of ignition quality for middle distillate fuels. Its features, such as low fuel volume requirement, complete test automation, and self-diagnosis, make it highly suitable for commercial oil industry and research applications. Operating and test conditions were examined in the context of providing a high correlation with cetane number (CN), as determined by the ASTM D-613 method. Preliminary investigation indicates that the IQT results are highly repeatable (± 0.30 CN), providing a high sensitivity to CN variation over the 33 to 58 CN range.

Several diesel injection systems were selected for evaluating the effects of fuel properties on diesel spray characteristics. Fuel properties that were examined were viscosity and specific gravity. The selected injection systems were operated on nine test fuels covering a broad range of viscosity and specific gravity. High-speed movies were taken of the fuels being injected into a high-pressure environment. Penetration and cone angle data were reduced from the movies and used as a basis for fuel-to-fuel comparisons. In addition, drop size distribution data were obtained for one injection system operating on four fuels with different viscosities. Fuel viscosity was found to have an effect on spray tip penetration. For a pintle-type nozzle as fuel viscosity increased, the tip penetration rate decreased. Tip penetration rate from a pressure time injection system was proportional to the fuel viscosity, in that as viscosity increased, tip penetration increased.