Numerical Analysis of Hydrogen Peroxide Addition and Oxygen-Enriched Methane Combustion

Abstract

Methane (CH4)/air lean combustion can be enhanced by increasing the concentration of the oxidizer, like oxygen (O2) enrichment, or adding a strong oxidant to the reactant. Hydrogen peroxide (H2O2) is a strong oxidizer that yields O2, steam, and appreciable heat after decomposition. This study numerically investigated and compared the effects of H2O2 and O2-enriched conditions on the adiabatic flame temperature, laminar burning velocity, flame thickness, and heat release rates of CH4/air combustion using the San Diego mechanism. The result showed that in fuel-lean conditions, the adiabatic flame temperature changed from H2O2 addition > O2-enriched scenario to O2-enriched scenario > H2O2 addition with increasing α. This transition temperature was not affected by the equivalence ratio. Adding H2O2 enhanced the laminar burning velocity of the CH4/air lean combustion more than the O2-enriched scenario. The thermal and chemical effects are quantified in various H2O2 additions, and it is found that the chemical effect has a noticeable contribution to the laminar burning velocity compared with the thermal effect, especially in higher H2O2 addition. Further, the laminar burning velocity had a quasi-linear correlation with (OH)max in the flame. The maximum heat release rate was observed at lower temperatures for H2O2 addition and higher temperatures for the O2-enriched scenario. The flame thickness was significantly reduced upon adding H2O2. Finally, the dominant reaction to the heat release rate changed from the reaction of CH3 + O ↔ CH2O + H in the CH4/air or O2-enriched scenario to the reaction of H2O2 + OH ↔ H2O + HO2 in the H2O2 addition scenario.

Temperature-Dependent Functions of the Electron–Neutral Momentum Transfer Collision Cross Sections of Selected Combustion Plasma Species

“…Fourth, the inclusion of molecular oxygen herein (although not an ordinary combustion product gas) is justified, because despite being a reactant oxidizer species that is consumed during combustion, it may still exist in the combustion products (and thus, in the plasma mixture) at a small concentration, in the case of the lean fuel (oxygen-enriched) mode of combustion [53,54]. Similarly, the inclusion of molecular hydrogen (despite being a fuel that is consumed during combustion) in the current study can be justified through the opposite fuel-rich or fuel-enriched combustion modes [55,56], with hydrogen being the fuel or a component of it.…”