polttolämpötila

Polttolämpötila, or flame temperature, is a concept in combustion science that refers to the temperature of the flame or the combustion products under burning conditions. In many contexts it is taken to mean the adiabatic flame temperature—the theoretical maximum temperature reached when a fuel reacts completely with an oxidizer at a given initial temperature and pressure, with no heat loss to the surroundings.

Actual flame temperatures are lower than the adiabatic value due to heat losses, radiation, incomplete combustion, and dilution by inert gases. The temperature depends on the fuel, the oxidizer (typically air or oxygen-enriched air), the equivalence ratio (fuel–air ratio), pressure, and diluents such as nitrogen or carbon dioxide. For hydrocarbon–air flames, adiabatic temperatures typically lie in the range of about 1800 to 2300 kelvin; methane–air flames have an adiabatic temperature around 2220 K. Real flames under common operating conditions often peak around 1500–2000 K, depending on geometry and quenching effects.

Measurement and estimation of polttolämpötila use experimental techniques such as spectroscopic emission measurements and microthermocouples, as well as computational methods based on chemical kinetics and enthalpy balance. In engineering, the flame temperature informs burner and furnace design, material selection, and control strategies, and it relates to pollutant formation, notably NOx, which tends to increase with higher flame temperatures.

Polttolämpötila is distinct from ignition temperature, which is the temperature at which a mixture will ignite spontaneously without an external ignition source.