What is the cetane rating of diesel fuel?
What is the cetane rating of diesel fuel?
Modern highway diesel engines tend to require fuel with a cetane number ranging from 45 to 55. Typically, regular no. 2 diesel has a cetane number of 40 to 42, while Cenex® Premium Diesel has a cetane number of 47 to 52.
How is cetane number calculated?
Cetane numbers are measured using a method developed in the 1930s by the Cooperative Fuel Research (CFR) Committee, and later standardized as ASTM D613. The test involves running the fuel in a single cylinder, continuously variable compression ratio CFR Cetane Engine.
Is too much cetane bad?
One of the very few benefits of cetane is its ability to speed up the ignition process in the cylinder, aiding with cold-weather engine starting. If you increase the cetane number too high (55 and beyond), it can deteriorate the fuel and actually cause a reduction in overall engine performance.
What is a good cetane index?
Typical values. Generally, diesel engines operate well with a CN from 48 to 50. Fuels with lower cetane number have longer ignition delays, requiring more time for the fuel combustion process to be completed. Hence, higher speed diesel engines operate more effectively with higher cetane number fuels.
Where does the cetane number of a fuel come from?
When a fuel has the same ignition delay period as a mixture of the two primary reference fuels, its cetane number is derived from the volume percent of cetane and heptamethylnonane, as follows: In routine operations, the two primary reference fuels are replaced by two secondary reference fuels: T-fuel and U-fuel.
How is the cetane number related to the ignition delay?
Definition. Cetane number (or CN) is an inverse function of a fuel’s ignition delay, the time period between the start of ignition and the first identifiable pressure increase during combustion of the fuel. In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower Cetane fuels.
What is the cetane number of Alpha methylnaphthalene?
Alpha-methylnaphthalene, which has a long delay period, was assigned a cetane number of 0, but has been replaced as a reference fuel by 2,3,4,5,6,7,8-heptamethylnonane, whose cetane number is 15. All other hydrocarbons in diesel fuel are indexed to cetane as to how quickly they ignite under compression, i.e., diesel engine conditions.
What’s the difference between cetane and CCAI in diesel?
In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower Cetane fuels. Cetane numbers are only used for the relatively light distillate diesel oils. For heavy (residual) fuel oil two other scales are used, CCAI and CII .