Coupling Analysis of the Flame Emission Spectra and Explosion Characteristics of CH4/C2H6/Air Mixtures

Abstract

This work presents the coupling relationship between the flame emission spectra and explosion characteristics of CH4/C2H6/air mixtures ([CH4] = 7.0, 9.5, and 11.0 vol %; [C2H6] = 0–2.0 vol %). A 20 L spherical explosion testing system was used to record the explosion pressure–time curves of the CH4/C2H6/air mixtures at room temperature (18–22 °C) and pressure (1 atm). A flame emission detection system was used to capture the emission spectra of H* and OH* during the gas mixture explosions. In addition, sensitivity analysis was carried out on the change in the mole fraction of the explosion intermediates in a detailed mechanism (GRI-Mech 3.0). The results demonstrate that Pmax and (dP/dt)max increased with the addition of C2H6 for the fuel-lean state, while the time to reach Pmax decreased with the addition of C2H6. For the stoichiometric and fuel-rich states, the opposite was true. Additionally, the trends of Pmax, (dP/dt)max, and time to reach Pmax are essentially in accordance with those of Imax, (dI/dt)max, and time to reach Imax for H* and OH*. Furthermore, on the basis of the sensitivity analysis, the C2H6 addition has a positive effect on the production of OH* at the time corresponding to (dP/dt)max for the fuel-lean state, while the formation of OH* is inhibited by C2H6 at the time to reach (dP/dt)max for the stoichiometric and fuel-rich states, which is consistent with the experimental results.