NUMERICAL INVESTIGATION OF CH4 CO2/AIR AND CH4/CO2/O-2 COUNTERFLOW PREMIXED FLAMES WITH RADIATION REABSORPTION/

Effects of radiative heat loss on temperatures and extinction characte ristics of CH4/CO2/air and CH4/CO2/O-2 counterflow premixed flames wer e numerically investigated by using the detailed chemistry and transpo rt properties with emphasis on assessing the importance of radiation r eabsorption. Radiative transfer was calculated using the discrete ordi nate method along with the grey gas assumption. Results show that radi ation reabsorption has little influence on the temperatures and extinc tion limits of CH4/ air counterflow premixed flames of low equivalence ratio. However the radiation reabsorption has a significant effect on the flame temperatures and extinction limits of CH4/CO2/air and CH4/C O2/O-2 counterflow premixed flames, especially on the radiation extinc tion limits. The flammable region of CH4/CO2/air counterflow premixed flames becomes smaller as the fraction of CO2 added to air increases. Radiation extinction of CH4/CO2/O-2 flames occurs at higher stretch ra tes than that of CH4/air flames.