Adiabatic Combustion Temperature Calculator
Select a fuel, enter the air-fuel equivalence ratio and initial reactant temperature to estimate the adiabatic flame temperature.
Use the Adiabatic Combustion Temperature Calculator
Combustion Inputs
Temperature of fuel + air before ignition
Select a fuel and press Calculate
Flame Temperature vs. Equivalence Ratio (φ)
Interpretation
Fuel Reference — Adiabatic Flame Temperature at Stoichiometric, 25 °C Reactants
| Fuel | LHV (kJ/kg) | Stoich AFR | T_ad (°C) | Notes |
|---|---|---|---|---|
| Methane (CH₄) | 50,050 | 17.2 : 1 | ~1,950 | Natural gas / CNG primary component |
| Propane (C₃H₈) | 46,350 | 15.7 : 1 | ~1,995 | LPG; slightly higher T_ad than methane |
| Hydrogen (H₂) | 119,960 | 34.3 : 1 | ~2,210 | Highest LHV/kg; products are H₂O only |
| Gasoline (~C₈H₁₈) | 44,500 | 14.7 : 1 | ~2,030 | Typical pump gasoline blend |
| Diesel (~C₁₂H₂₆) | 42,500 | 14.5 : 1 | ~2,020 | Compression ignition; similar to gasoline |
| Ethanol (C₂H₅OH) | 26,800 | 9.0 : 1 | ~1,920 | Lower LHV offset by lower product mass |
Summary
The adiabatic flame temperature is the theoretical maximum temperature combustion products reach when no heat is lost to surroundings. It is calculated by equating the enthalpy released by the fuel (lower heating value) to the sensible enthalpy gained by the combustion products. Real flame temperatures are lower due to heat losses, dissociation, and incomplete combustion. This tool uses a lookup-table approach with mean product Cp values, giving results accurate to within ~2–5% of full equilibrium calculations for near-stoichiometric mixtures.
How it works
- Select a fuel from the preset list — its lower heating value (LHV) and stoichiometric air-fuel ratio load automatically.
- Set the equivalence ratio (phi, φ): 1.0 = stoichiometric; < 1.0 = lean (excess air); > 1.0 = rich (excess fuel).
- Enter the initial reactant temperature (fuel + air before ignition).
- The calculator finds the mass of products per unit mass of fuel, then applies T_ad = T_in + LHV / (m_products × Cp_products).
- Results show adiabatic flame temperature, temperature rise, and an equivalence-ratio sweep chart.
Use cases
- Estimate burner exit temperature for gas turbine combustor preliminary design.
- Compare adiabatic temperatures across fuels when evaluating alternative energy sources.
- Assess lean-premixed combustion margins to avoid autoignition or blowout.
- Validate equilibrium combustion software outputs against a quick analytical estimate.
- Classroom demonstration of how excess air (lean mixtures) lowers flame temperature.