Abstract: By using the standard fuels and the corresponding air volume, the power function equation of "cetane number-air volume" was summarized through big data calculation and evaluation, the cetane number and air volume was measured by FCD compression ratio method, and the cetane number of the diesel fuel sample was obtained by checking the cetane number of the sample. There was no significant difference between FCD compression ratio method, CFR-ASTM method and FCD interpolation method. Comparing FCD (including FCD compression ratio method and FCD interpolation method) with CFR-ASTM method, FCD method could realize bi-directional forward and inverse adjustment of air volume; compared with the FCD interpolation method, the FCD compression ratio method could find the cetane number of the diesel sample in the "cetane number-air volume meter", but the FCD interpolation method must test two standard fuel air volumes (the sample air volume must be within the range of two standard fuel air volumes) through the interpolation method to calculate the cetane number of the sample. The diesel cetane number determination by FCD compression ratio method had high precision and repeatability.

Key words: diesel, cetane number, compression ratio method, air volume, power curve, interpolation