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D19A99G

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- TL;DR Summary
- Calculation of the theoretical value of AFR of ethanol

First I have seen a few forums dotted about covering this subject already, however I couldn't find exactly what I was looking for so I apologise if its somewhere on here already.

I am trying to calculate the AFR value for pure ethanol.

I am only including oxygen in the category of "air" due to other elements being inert.

The balanced equation is C2H5OH + 3O2 = 3H2O + 2CO2.

When I then calculate the AFR while also considering that oxygen only makes up 21% of air, the value I get is approximately 9.9. Which is different to the widely used value of 9. Is there something I'm doing wrong or has the value of 9 only being achieved through practical tests which cannot be replicated via theory?

Ethanol mass = 46, Oxygen mass = 96

Air mass = Oxygen*4.76 = 456.96

AFR = 456.96/46 = 9.93

When; C=12amu, H=1amu, O=16amu

I am trying to calculate the AFR value for pure ethanol.

I am only including oxygen in the category of "air" due to other elements being inert.

The balanced equation is C2H5OH + 3O2 = 3H2O + 2CO2.

When I then calculate the AFR while also considering that oxygen only makes up 21% of air, the value I get is approximately 9.9. Which is different to the widely used value of 9. Is there something I'm doing wrong or has the value of 9 only being achieved through practical tests which cannot be replicated via theory?

Ethanol mass = 46, Oxygen mass = 96

Air mass = Oxygen*4.76 = 456.96

AFR = 456.96/46 = 9.93

When; C=12amu, H=1amu, O=16amu