Extinction Limits and Flame Structure of C1–C3 Hydrocarbon Fuels Oxidized by Hydrogen Peroxide-Steam and Oxy-Steam in Counterflow Diffusion Flames

Hydrogen peroxide (HP) is a promising oxidizer due to its decomposition into O₂ and H₂O with significant energy release. This study investigates the use of HP-steam as an oxidizer in opposed-flow laminar diffusion flames and compares its performance with O₂/H₂O (Oxy-steam). The extinction limits of H₂/CH₄, C₂H₄, C₂H₆, and C₃H₈ flames were measured, and their flame structures were analyzed by using gas chromatography (GC). HP-steam significantly increased flame temperatures and extinction limits, while numerical simulations overpredicted the extinction limits and showed partial deviations from species profiles, particularly for H₂, CO₂, and CO in HP-steam flames. The difference may be attributed to cellular instability caused by lower effective Lewis numbers (Le_e < 0.8), which the 1-D simulations do not account for. The radical index RiOH and transport-weighted enthalpy (TWE) were evaluated for predicting the extinction limits and found strong correlations for Oxy-steam flames and moderate agreement for HP-steam flames. Discrepancies between experimental results and model predictions for HP-steam flames emphasize the need for improved chemical kinetic models. Additionally, HP-steam and Oxy-steam oxidized flames avoid NOx formation and could facilitate carbon capture. Overall, HP shows potential as an oxidizer in enhancing flame stability and reducing NOx, paving the way for further research into its application in turbulent flames.