By Ibrahim Alhamad
Diesel engines and gasoline engines are the most widely used primary sources of power in automobiles and the sheer number of them makes the issue of emissions from these engines an important one. It gives a comparison of the amounts of different pollutants in the exhaust of diesel and petrol engines formation of NOx and control methods. The main source of NOx in diesel engine emissions is the oxidation of the nitrogen in the air at the high temperatures in the cylinder during combustion. As the reaction mixture cools during the expansion stroke and exhaust blow down, the reactions of NOx freeze and NO is left in concentrations much higher than its equilibrium concentration.