Community Research and Development Information Service - CORDIS

A fuel quality rating method

Work has been performed to create a comprehensive database of performance and combustion data for a range of fuels, using a Ricardo Proteus single cylinder direct injection diesel engine. The validity of this database was demonstrated by the use of reference tests and statistical analysis and suitable correlation techniques were developed and an extensive study was performed of the correlation between performance and combustion parameters. In tests representing a turbocharged aftercooled direct injection diesel engine, typical of European truck practice, no single parameter will rank fuels correctly for all aspects of performance at all conditions.
Other fuel related factors such as physical properties and the use of an ignition improver do affect the correlation of performance with cetane number under certain conditions.
Compared to cetane number, other parameters such as ignition delay measured at certain conditions are better predictors of fuel performance in several important areas, notably hydrocarbon emissions at light load retarded conditions, fuel consumption and some aspects for cold starting. However, cetane number is a better predictor of combustion noise index, light load hydrocarbons at advanced timings and cold starting behaviour at 0 C.
No combustion parameter was found which would predict variations in nitrogen oxide emissions.
Tests were unable to show any significant correlation with particulate emissions except under light load retarded conditions, where some correlation was seen corresponding with the correlations seen for hydrocarbons.
The use of ignition delay in place of cetane number as a fuel quality rating parameter has been seen under certain conditions to reduce the influence of other fuel related factors while improving the linearity and sensitivity of the relationship.
These data demonstrate that scope exists for improving upon the current method of rating the ignition quality of diesel fuels for compression ignition engines.

Reported by

Ricardo Consulting Engineers
Bridge Works
BN43 5FG Shoreham by Sea
United Kingdom
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