Experimental and chemical kinetic modeling study on the inhibition performance of pentauoroethane blended with carbon dioxide in methane-air mixture explosions

Abstract

To explore the inhibition effectiveness and mechanisms of pentafluoroethane (C2HF5), carbon dioxide (CO2), and their blends, 9.5% methane (CH4)-air mixture explosions under different inhibitors were tested by employing a 20 L spherical explosion system. A quadratic regression model was developed to predict impacts of factors on maximum explosion pressure (pm) through response surface method. The reactions and mechanisms under blended inhibitors were numerically investigated. Results depicted that increasing volume fractions of inhibitor led to decrease in pm, maximum rate of pressure rise, and delay in explosion induction time. Blended inhibitors demonstrated superior inhibition effectiveness, optimal inhibition-environmental was achieved at 4.5% C2HF5 blended with 5.5% CO2. A quadratic polynomial relation existed among pm, volume fractions of C2HF5, CO2, and CH4 during the explosion. Key free radicals were weakened and the promoted explosive elementary reactions were primarily inhibited. CH4+OHCH3+H2O and CH4+HCH3+H2 were the most diminished reactions by blended inhibitors compared to CO2 alone. Carbon-containing reactions R82 and R84, and fluorinated reactions R1025 and R1099 reduced the key free radicals, interrupted the chain reactions and promoted the production of HF. Findings will provide new ideas for prevention of CH4-air mixture explosions and reduce hazardous effect.