Effect of Different Kinds of Dilution Gases on the Combustion with Highly Preheated, Oxygen-Deficient Air.

Under the condition of oxygen-deficient high temperature air combustion with gaseous fiuels, NOx emission is greatly suppressed. In high temperature air combustion of LPG, as the oxygen concentration decreases, combustion flame becomes larger, and green or blue flame derived from CH and C2 radicals is observed with N2 or Ar dilution respectively. On the other hand, purple or flameless flame from broad bands between 280 nm and 450 nm is observed with CO2 dilution in the same condition. The order of suppressing effect on NOx emission is Ar