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How to Increase the Cetane Number of Diesel Fuel?

Such additives as nitro compounds or synthins are added to diesel fuel to increase its cetane number.  In practical terms, the special equipment in the USB line is used to inject additives and obtain homogenized fuels.  They are considered to be an integral part of the production process when increasing the cetane number by a described method.

The combustion of diesel fuels is affected by the design of the equipment and its operational principles.  The combustion chamber should be designed in such a way that it will benefit the vortex formation (when the air is compressed) that allows for the reduction of fuel heating.   It is desirable to use cast iron pistons, as they have a lower thermal conductivity that reduces the combustion distance (the air and fuel are heated actively).

The fractional composition of fuel is needed while assessing the quality of diesel. This composition may be defined by the flash temperature or in the same way as fuel composition.

How to Define the Cetane Number?

A test engine is used to measure the cetane number of diesel fuel.  When using other mehods of measurig the cetane number, the result will depend on the diesel fuel composition.  The motor method provides the exact results for the fuels with any fractional composition.  The various express analyzers require the recalibration when changing from one type of oil product to another, which is very difficult and time consuming.

In general, three approaches are used to identify an accurate value of the cetane number: (1) flare coincidence; (2) ignition lag; and (3) the critical rate of compression.  The ‘method of flare coincidence has gained a widespread acceptance.  It is realized by such types of equipment as IT9-3, It9-3M, or ITD-69 which have single-cycle four stroke engines.  When testing, the shaft speed should be maintained at the level of 900±10 revolutions per minute (rpm).

The cetane number of diesel fuel is largely determined by the hydrocarbon composition.  The cetane number of the benzene hydrocarbons is the  lowest while that of the paraffin hydrocarbons is the highest.