Thermodynamics
Combustion Stoichiometry Simulator
Examine the stoichiometry of hydrocarbon combustion. Adjust carbon and hydrogen atoms alongside air feeds to calculate actual air-fuel ratios, exhaust products, and adiabatic flame temperatures.
Fuel
Octane
C8H18
Air Feed
20% Excess
Dynamic mix
Output
CSV
Stoich table
Parameters
Fuel Molecule Preset
Sweep Air Feed Cycle
Stoichiometric Governing Equations
Theoretical Air Coefficient
a_th = C + H/4
Actual Air Coefficient
a_act = a_th · (1 + ExcessAir / 100)
Adiabatic Flame Temp
T_ad = T_0 + LHV / ((1 + AF) · Cp)
Exhaust Product Mix (moles per mole of fuel): 8.0 CO₂, 9.0 H₂O, 2.5 O₂, and 56.4 N₂.
Thermal cooling occurs at higher excess air feeds due to the large mass of non-reacting Nitrogen and excess Oxygen absorbing combustion heat.
Linked Combustor Core
Flame Temperature
2061°C
Air-Fuel Ratio
18.03:1
Theor. Air (a_th)
12.50moles
Actual Air (a_act)
15.00moles
Adiabatic Flame Temp vs Excess Air Feed
Reaction Stoichiometry Data
| Excess Air (%) | Air-Fuel Ratio | Adiabatic Flame Temp (°C) | Exhaust O₂ (moles) |
|---|---|---|---|
| 0 | 15.03 | 2443 | 0.00 |
| 20 | 18.03 | 2061 | 2.50 |
| 40 | 21.04 | 1783 | 5.00 |
| 60 | 24.04 | 1572 | 7.50 |
| 80 | 27.05 | 1407 | 10.00 |
| 100 | 30.05 | 1273 | 12.50 |
| 120 | 33.06 | 1163 | 15.00 |
| 140 | 36.07 | 1070 | 17.50 |
| 160 | 39.07 | 992 | 20.00 |
| 180 | 42.08 | 925 | 22.50 |
| 200 | 45.08 | 866 | 25.00 |