掺氢甲烷混合气体爆炸极限试验研究及动力学分析

This study employs an integrated experimental-computational approach to evaluate how hydrogen blending alters the explosion characteristics of methane-air mixtures. Experimentally, explosion-limit maps were established in a sealed vessel operated under carefully controlled initial temperature and pressure conditions. Homogeneous CH₄ H₂ air mixtures with various hydrogen volume fractions were prepared by partial-pressure filling followed by thorough mixing. For each composition, the lower and upper explosion limits were identified through synchronized observations of visible flame propagation and post-test pressure traces. Each test condition was repeated at least three times to ensure statistical reproducibility and consistent limit assignment. Computationally, detailed-chemistry simulations within the CHEMKIN framework quantified the constant-volume adiabatic flame temperature, adiabatic pressure rise, and the time-resolved evolution of the radical pool (· H, · OH, · O) . Complementary reaction-path and local sensitivity analyses were conducted to isolate rate-controlling steps near the flammability boundaries, thereby linking observed macroscopic limit shifts to the underlying chain-branching kinetics. To benchmark common engineering practice, predictions from Le Chatelier’s mixing rule were compared with both experimental measurements and kinetics-based simulations, with special attention paid to the low-hydrogen regime of practical interest. Results show that the explosion-limit interval broadens systematically with increasing hydrogen fraction. The expansion is modest below approximately 20% H₂ , where Le Chatelier’s rule remains in close agreement with experiments. However, at higher hydrogen contents, the broadening accelerates in an exponential-like fashion, and the empirical rule increasingly underestimates the expanded limits, underscoring the dominant role of kinetics beyond simple mixture averaging. Notably, simulations indicate only minor changes in adiabatic temperature and adiabatic pressure rise relative to methane-air baselines, yet they reveal substantially elevated concentrations of ·H and ·OH. These increases shorten induction times, intensify chain branching, and help sustain flame propagation—providing a mechanistic foundation for the observed broadening of explosion limits. Overall, the combined dataset delineates the applicability domain of Le Chatelier’s rule and supports kinetics-informed assessments at higher hydrogen fractions, thereby defining safer operating guidelines for hydrogen-enriched natural gas systems.