Adiabatic Flame Temperature Calculator

The Adiabatic Flame Temperature Calculator finds the maximum theoretical temperature a fuel-oxidizer mixture can reach during combustion when no heat escapes to the surroundings — a critical value in engine design, burner engineering, and fire safety analysis. Select your fuel type and oxidizer type, then enter the equivalence ratio, initial temperature, pressure, and combustion type to get the adiabatic flame temperature in K, °C, and °F. Secondary outputs include the heat of reaction and mixture type (lean, stoichiometric, or rich).

φ = 1 is stoichiometric, φ < 1 is lean, φ > 1 is rich

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atm

Results

Adiabatic Flame Temperature

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Temperature (°C)

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Temperature (°F)

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Heat of Reaction

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Mixture Type

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Frequently Asked Questions

What is adiabatic flame temperature?

Adiabatic flame temperature is the maximum temperature achieved during combustion when no heat is lost to the surroundings. It represents the theoretical maximum temperature possible for a given fuel-oxidizer combination under adiabatic conditions.

What does equivalence ratio (φ) mean?

Equivalence ratio is the ratio of actual fuel-to-air ratio to the stoichiometric fuel-to-air ratio. φ = 1 means stoichiometric combustion, φ < 1 indicates lean combustion (excess air), and φ > 1 indicates rich combustion (excess fuel).

What's the difference between complete and incomplete combustion?

Complete combustion assumes all fuel converts to CO₂ and H₂O, while incomplete combustion considers chemical equilibrium and may produce CO, H₂, and other intermediate species. Incomplete combustion typically results in lower flame temperatures.

Why do lean mixtures typically have lower flame temperatures?

Lean mixtures contain excess air (nitrogen) that absorbs heat without participating in combustion. This additional mass increases the heat capacity of the products, resulting in lower final temperatures compared to stoichiometric mixtures.

How does pressure affect adiabatic flame temperature?

Pressure has a relatively small direct effect on adiabatic flame temperature for most fuels. However, higher pressures can shift chemical equilibrium and affect dissociation of products at very high temperatures.

Which fuels produce the highest flame temperatures?

Hydrogen typically produces the highest adiabatic flame temperatures (around 2400K with air), followed by acetylene and methane. The exact temperature depends on the oxidizer used and mixture ratio.

Why is initial temperature important?

Higher initial temperatures of reactants result in higher flame temperatures because less energy is needed to heat the reactants to ignition temperature, leaving more energy available to heat the products.