Question

Define Octane number and Cetane number?

in 200 words

Answer 1

Octane number and Cetane number are used to characterize the combustion phenomena in petrol and diesel fuels respectively.

S.NO	Octane number	Cetane number
1	Octane number of a petrol sample is defined as the % of iso-octane Octane in the mixture of iso-octane & n-heptane, which has similar,knocking to the petrol sample.,.	Cetane number of diesel sample is defined as % of nhexadecane,in the mixture of n-hexadecane & 2-methyl naphthalene which,has same ignition character like the ignition character of the diesel under,test.
2	Octane rating is used for petrol	Cetane rating is used for diesel
3	The fuel with high octane rating has low cetane number	The fuel with high cetane rating has low octane number
4	Octane number of good petro should be atleast,85 for motorcycle and cars 100 for aeroplanes and helicopters	Cetane number for good diesel should be 25 for low speed egine,35 for medium speed engine and 45 for high speed engine
5	Octane number of petrol can be increased by adding benzene or toluene	Cetane number diesel can be increased by adding by adding ethyl nitrate or acetone peroxide
6	Significance : High octane in gasoline allows the fuel to resist preignition under high pressure and heat	Significance : High cetane has a low resistance to preignition, while high,octane has a high resistance to preignition; both high cetane and high octane provide the ability to extract more power from fuel.