Dimensions of CH sub(4)-Jet Flame in Hot O sub(2)/CO sub(2) Coflow

The present study has numerically simulated the oxy-fuel combustion of a methane (CH sub(4)) jet in hot coflow (JHC). The main objective is to investigate the influences of the oxygen (O sub(2)) molar fraction (X sub(O2) super(*)), temperature (T sub(cof) super(*)) and velocity (v sub(cof) super(*)) of the O sub(2)/CO sub(2) coflow on dimensions of the JHC reaction zone or flame. The simulations use the model of eddy dissipation concept (EDC) with the detailed chemical mechanism described by GRI-Mech 3.0. To validate the modeling, several air-fuel JHC flames are predicted under the same conditions of the work of Dally et al. [Proc. Combust. Inst.2002, 29, 1147-1154]; the predictions match well with the measurements. Results suggest that, as either X sub(O2) super(*) or v sub(cof) super(*) decrease or T sub(cof) super(*) increases, the volume of the JHC reaction zone increases and hence the overall oxidation rate of CH sub(4) decreases. In particular, raising the coflow speed v sub(cof) super(*) causes the flame to be significantly thinner but only slightly longer. It is also demonstrated that the oxy-fuel reaction zone is larger, and so, the temperature is lower than the air-fuel counterpart. Besides, under identical conditions, the oxy-fuel combustion produces more carbon monoxide than does the air-fuel combustion.