Single-valued prediction of markers on heat release rate for laminar premixed biogas-hydrogen and methane-hydrogen flames

Numerical studies on the 1-D laminar premixed flame were conducted utilizing the detailed mechanisms to evaluate the validity of several heat release rate (HRR) markers for the single-valued prediction on the HRR in a wide range of conditions. The biogas and methane with hydrogen enrichment are used as the fuel. The peak-to-peak correlation and the peak-to-integrated correlation of considered markers and HRR in premixed flames were established to examine their sensitivity to the equivalence ratio and the fuel composition. For both premixed biogas and methane flames considered, the O × CH₃ product has the almost constant correlation with peak or total HRR at different conditions. Thus the O × CH3 product is suggested as the most reliable indicator for the HRR imaging in the unstretched premixed flames with the unknown equivalence ratio. HCO is demonstrated to be a reliable marker in the premixed combustion, while the OH × CH₂O, H × CH₂O and H × HO₂ products are inadequate for the single-valued prediction on the HRR because their correlations with HRR are sensitive to the equivalence ratio, indicating that these markers cannot reflect the HRR change accurately if the local equivalence ratio is affected.