Development of a reaction mechanism of hydrogen production through rich methane-acetylene blending in a porous medium micro-combustor

Abstract

With the growing global focus on environmental and energy issues, hydrogen has garnered significant attention as a green energy source. It leads to extensive research on hydrogen production and storage. This study primarily investigates hydrogen production based on the non-catalytic reaction pathways of methane, using molecular dynamics to explore the combustion reaction pathways of methane under high equivalence ratio conditions, as well as the influence of acetylene blending on these reaction pathways. A porous medium micro-combustor is utilized as the reactor to study the effects of different blending ratios and equivalence ratios on hydrogen production efficiency. By analyzing several elementary reactions that play a major role in hydrogen production, the study examines the mechanisms and differences in the effects of blending ratio and equivalence ratio. The results show that increasing the equivalence ratio and blending ratio can both reduce the oxidation reactions of hydrogen by lowering the concentration of OH radicals during the post-combustion period. However, acetylene blending can enhance the chain reaction rate during the ignition delay period through oxidative dehydrogenation, thus accelerating the oxidation process of methane. The study also concludes that under high equivalence ratio conditions, further increasing the blending ratio can actually reduce flame stability, thereby affecting hydrogen production efficiency. The results indicate that at high blending ratios, the highest hydrogen production efficiency is achieved when the equivalence ratio is controlled at 1.35. Finally, the study investigates the effect of different inlet flow rates on hydrogen production efficiency under the condition of an equivalence ratio of 1.35. The findings show that, due to the sufficient size of the combustor allowing complete reaction of H radicals, the inlet flow rate has a minimal impact on hydrogen production efficiency, with the mass flow rate of hydrogen at the outlet being directly proportional to the flow rate of the mixed gas.