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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