Coupling Analysis of Chemiluminescence and Pressure Changes in CH4/Air Explosion Suppressed by NaHCO3 Powder

This paper presents the coupling relationship between the flame emission spectrum and explosion characteristics of CH4/air mixtures with NaHCO3 powder added. Due to the test of different concentrations of suppression powder in 20 L spherical-explosion-test devices, the flame emission spectrum and explosion pressure data were collected. In this experiment, four kinds of excited radicals, including CN*, HCHO*, CO*, and OH*, have a higher probability of being detected, and the changes of their existence duration and spectral intensity show strong regularity. Results reveal that for suppressant concentration in the range of 0–50 mg/L, together with the improvement of a suppression effect, the existence duration and spectral intensity of CN*, CO*, and OH* decrease, which is opposite to that of HCHO*. Besides, the spectral intensity of OH* and CO* shows a good linear relationship with the change of the maximum explosion pressure. Controlling the content of CN*, CO*, OH*, and HCHO* is of great significance in suppressing the explosion.