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Stochiometric Air - fuel Ratio And Actual Air - fuel Ratio

 STOCHIOMETRIC AIR FUEL RATIO :

 The Amount of air required to burn 1 kg of fuel for making complete combustion is known as air - fuel     ratio. It is also known as Stochiometric or Theoretical air - fuel ratio.

 STOCHIOMETRIC  AIR - FUEL RATIO :

       = Amount of air required for complete combustion /  Amount of  fuel used.

ACTUAL AIR- FUEL RATIO :

Practically , Air is required to make complete combustion of fuel is slightly more than the theoretical air . So, the excess air is supplied to obtain complete combustion. Therefore, the actual air-fuel ratio is slightly higher than the theoretical air -fuel ratio of stochiometric   air -fuel ratio.

Then, the percentage excess air can be calculated as

Percentage Excess Air = (Actual A/F ratio - Stochiometric A/F ratio)                                          / ( Stochiometric A/F ratio ) 

Note : Conversion of  volumetric analysis to mass analysis is done by multiplying its molecular weight.

Mass analysis = Volumetric analysis * Molecular weight  

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