The explosion enhancement of methane-air mixtures by ethylene in a confined chamber

Highlights: • Ethylene increases P_max, S_L, and (dP/dt)_max, while it shortens the combustion time. • Three combustion regimes were identified for the explosion of CH₄–C₂H₄-air mixture. • Ethylene accelerate the weight ratios of T_a/T_c and T_b/T_c in the explosion process. • The lowest heat loss and its fraction F_tran appear under stoichiometric conditions. • Ethylene promote the C₂ reactions involved in the explosion process. In the present work, the explosion of methane-ethylene-air mixtures within equivalence ratios from 0.72 to 1.3 and with an ethylene volume fraction from 0% to 100% at ambient temperature and pressure was experimentally investigated in a 20 L confined chamber. The deflagration parameters of maximum explosion pressure, maximum pressure rise rate, and explosion time indices were obtained on the basis of pressure-time curves. The explosion heat loss, heat loss fraction, and laminar burning velocity were calculated and analyzed. Moreover, sensitivity analysis was employed to identify the dominant elementary reactions contributing to the rise in pressure, the consumption of CH₄, and the production of OH radicals during the explosion process. The results indicated that ethylene increases the maximum explosion pressure, the laminar burning velocity, and the maximum pressure rise rate of methane-air mixtures, while it shortens the combustion time. Three combustion regimes for CH₄–C₂H₄-air mixtures were identified: the methane-dominant regime, transition regime, and ethylene-dominant regime. The lowest heat loss and its fraction F_tran appear under stoichiometric conditions, and the highest values occur at the equivalence ratio ϕ = 1.3. The results will be helpful for developing measures to prevent potential fire and explosion accidents.