Cetane Number and Cetane Index

It is a requirement of the European Specification for Automotive Diesel Fuel BS EN 590 that both the Cetane Number (CN) and Cetane Index (CI) are determined and reported. This article, which summarises the findings of an Energy Institute (EI) sponsored Technical Development Project carried out by Cliff Lilley, outlines a review of the suitability of the current CI equation used in IP 380 Calculation of Cetane Index of middle distillates by the four-variable equation (EN ISO 4264) (ASTM D 4737 procedure A**) for calculating CI, to predict CN as measured by IP 41 Determination of the ignition quality of diesel fuels - Cetane engine method (ASTM D 613).