Abstract: In order to improve the explosion suppression effect of a single type of detonation inhibitor on methane, the synergistic inhibition effect of silica powder and heptafluoropropane gas on 9.5% methane/air explosion was studied based on the self-built experimental platform. By changing the mass concentration of silica powder and the gas volume fraction of heptafluoropropane, the effects of the two independent and synergistic effects on the methane/air explosion characteristic parameters were studied. The results showed that under the combined action of heptafluoropropane gas and nano-silica powder, the gas-solid two-phase detonation suppressor exhibits synergistic inhibition on the explosion pressure, flame propagation velocity and flame propagation characteristics of 9.5% methane/air premixed gas inhibition. When the concentration of nano-silica powder reaches 0.10 g/L, adding heptafluoropropane gas with different volume fractions can have a good inhibitory effect on the explosion of 9.5% methane/air premixed gas. Under the condition of silica without heptafluoropropane, the maximum flame velocity decreased by 78.5%, and the maximum explosion pressure of the flame decreased by 79.7%, and the inhibition effect was the best. As the control parameters continue to increase, the suppression effect decreases. The mechanism of synergistic explosion suppression of gas-solid mixture was studied. It provides technical guidance for the application of two-phase explosion suppression technology.

Key words: methane explosion, silicon dioxide, HFC-227ea, flame velocity, the explosion overpressure