concept

Adiabatic flame temperature

The temperature the products of combustion would reach if every joule of reaction enthalpy went into heating them and none leaked away. It is an idealised ceiling: dry wood burning in Earth air gives about 2250 K, while real flames always run cooler because they radiate and convect heat out. Because the figure comes from an enthalpy balance rather than from how energetic the fuel is, any inert diluent with a large molar heat capacity pulls it down - CO₂ is 37 J/mol·K at 298 K against nitrogen's 29, so the same percentage of carbon dioxide cools a flame considerably harder. Once the calculated temperature falls below what the radical chain reaction needs, the flame simply cannot exist.