Differentiate between cetane number and octane number

The differences between cetane number and octane number are as follows :

Cetane number Octane number
Cetane number of a given diesel under test is defined as the percentage by volume of cetane in mixture of cetane and ∝-methyl naphthalene which exactly the knocking characteristics of the diesel under test. Octane number of given petrol under petrol under test is defined as the percentage by volume of is octane in mixture of is – octane and n-heptagon which exactly matches the knocking characteristics of the petrol under test .
Cetane number indicates knocking characteristics of diesel in diesel engine . Cetane number indicates knocking characteristics of diesel in diesel engine .
Higher the cetane number of diesel lesser is the knocking in diesel engine. Higher the octane number of petrol lesser is the knocking in petrol engine.
Higher cetane number is due to less compactness, double bonds, cyclic structure and branches in straight chain hydrocarbon . Higher octane number is due to more compactness, double bonds, cyclic hydrocarbon .
Fuel having higher cetane number has lower octane number and cannot be used in petrol engines. Fuel having octane number has lower cetane number and cannot be used in diesel engines.
The antiknock agents have high oxygen content. The antiknock agents do not contain oxygen.
Doping agents provide nascent oxygen at higher temperature to increase combustion rate and cetane number Doping agents undergo thermal degradation to form free radicals which reduce combustion rate increase octane number.

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