Theoretical AFR from elemental composition: AFR = (11.53·C + 34.34·(H − O/8) + 4.32·S) / 100, for mass fractions expressed in percent.
Formula
$$ AFR_\text{stoich} = \frac{11.53 C + 34.34 \left(H - \tfrac{O}{8}\right) + 4.32 S}{100} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $C$ | Carbon mass % | % m/m | ultimate analysis |
| $H$ | Hydrogen mass % | % m/m | ultimate analysis |
| $O$ | Oxygen mass % | % m/m | ultimate analysis |
| $S$ | Sulphur mass % | % m/m | ISO 8754 |
| $AFR$ | Stoichiometric air-fuel ratio | kg air / kg fuel | result |
Sources
- Heywood - Internal Combustion Engine Fundamentals.