Promotion and Inhibition of the Combustion of Methane in Oxidative Gases with Various Oxygen Concentrations by Fluorinated Hydrocarbons

Experimental data on the combustion characteristics of methane-oxidative gas (O-2 + N-2)-inhibitor (CHF3, C2HF5, and C4F10) mixtures and an analysis thereof show that fluorinated hydrocarbons (HFC and FC) exhibit the properties of both flame inhibitors and promoters. The flammability concentration limits, maximum explosion pressure Delta P-max, maximum explosion pressure rise rate (dP/dt)(max), and laminar flame speed S-u are measured for near-limit methane-oxidative gas-fluorinated hydrocarbon mixtures. It is demonstrated that, when added to lean near-limit mixtures, HFC and FC behave as an additional fuel. Calculations of the thermodynamic characteristics of reactions involving fluorinated hydrocarbons capable of acting as both an inhibitor and oxidizer show that such reactions have significant heat effects, 150-700 kJ/mol, with the respective adiabatic temperatures being as high as 900-1800 K. The results of the present study suggest that the procedure of selecting fluorinated hydrocarbons for practical applications as fire and explosion sup-pressants should include careful tests of their promoting effect.