Figure l(a) shows the schematic for flame cooling
with recirculated exhaust gas. High velocity burners
use the high momentum of the flame jet to mix with
gases from the combustion chamber. These exhaust
gases, entrained in the flame, are cooler than the fresh
combustion products in the flame. Heat release during
the combustion process (see Fig. l(b)) happens for
almost all flames due to radiation. Enhanced cooling
by cooling rods is applied to reduce thermal NO-formation
in domestic water heaters or boilers (see.
Fig. 2). Surface combustion with enhanced radiation
is also applied mainly to smaller domestic applications.
To improve flame stability and complete
combustion, many investigations with catalytic
coatings were carried out.