Pick your Fuel Type and Oxidizer Type, set the Equivalence Ratio (φ), Initial Temperature, Pressure, and Combustion Type, and the Adiabatic Flame Temperature Calculator gives you the theoretical peak temperature your reaction can reach — plus readouts in °C and °F, Heat of Reaction, and Mixture Ratio.
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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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.
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).
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.
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.
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.
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.
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.