Degree of unsaturation

$D U = 1 - U F A + 2 \times 2 - U F A + 3 \times 3 - U F A + 4 \times 4 - U F A$

Fuel properties such as cetane number (CN), iodine value (IV) and oxidation stability (OS) are mainly determined by the degree of unsaturation (DU) of fatty acid in raw oils. When the degree of unsaturation of raw oils fatty acid is lower than 133.13, cetane number (GB/T 20828-2007) and iodine number (EN 14214) meet the standards.