cetane number

                          CETANE NUMBER Cetane number :  →the knocking characteristics of the diesel is expressed in the terms of cetane number. →cetane, is saturated hydrocarbon which has very short ignition lag as compare to any commercial diesel fuel. Hence it’s cetane number is taken as 100. →on the other hand 2-methyl naphthalene (aromatic hydrocarbon ) has very long ignition lag as compare to any commertial diesel oil . Hence it’s octane number is taken zero. →cetane number of diesel oil is defined as “the percentage of the cetane number in the mixture of the cetane & α-methyl naphthalene which exactly matches in it’s knocking characteristics with oil under test” →the cetane number of the high speed, medium speed , low speed diesel is 45,35,25. →cetane number of the oil can be improved by adding dopes like ethyl nitride, isoamyl nitrate , acetone peroxide etc. →dopes are added in small amount about 2%. →use of dopes is not common as TEL in gasoline. →in petrol engi