Cetane index

The cetane index (abbreviated CI) describes - like the cetane number - the ignitability of diesel fuel and similar substances ( eg petroleum, gas oil components, marine diesel oil). The index is a purely from density (kg / L) and the boiling curve (EN ISO 3405:2000 ) calculated size. This international standard was originally developed to determine the ignitability if a test engine was available. Is this restriction no longer applies today, specifying the cetane index - along with the cetane number - still (DIN EN 590).


Originally, the index has been after the 2- parameter method calculated (ASTM D976 -06):

CI = 454.74 to 1641.416 774.74 * density * Dichte2 - 0.554 97.803 * T50 * ( LOG ( T50 ) ) 2

With the T50 boiling point in ° C, at which 50% of the product volume has evaporated. However, this method was not precise enough, so DIN EN 590 ( ISO 8217:2005 and DIN ) on the so-called 4- parameter method (DIN EN ISO 4264:2007 ) is due, in which:

T10 ( temperature in ° C at which 10% by volume of the product are evaporated)

As well as

T90 (temperature in ° C, at which 90% by volume of the product are evaporated)

Be used as an additional parameter.

As an auxiliary variable still serves:

B = E -3, 5 * (Density -0, 850 ) -1

Then the result for the cetane index:

CI = 45.2 0,0892*(T10-215) (0,131 0,901*B)*(T50-260) (0,0523-0,42*B)*(T90-310) 0,00049*((T10-215)2-(T90-310)2) 107*B 60*B2 (rounded to 0.1 )

The cetane index is not applicable to pure hydrocarbons, cetane number does not affect the index, and distillates from coal will not display correctly. However, the method can be applied for products made of tar sands and shale oil. The DIN EN ISO 4264 recommended areas for the application of this method are:

Cetane number of 32.5 to 56.5 Density from 0.805 to 0.895 kg / L T10 171-259 ° C T50 212-308 ° C T90 251-363 ° C