Effects of promotion and suppression by pentafluoroethane on methane explosions: Experimental and simulation discussion

Methane (CH 4 ), as an important chemical fuel, has never ceased its explosion prevention and control research. This study combines experimental and molecular dynamics simulations to investigate the impact and mechanisms of pentafluoroethane (C 2 HF 5 ) on CH 4 explosions. By analyzing the variation of explosion pressure, the relationship between the volume fraction of C 2 HF 5 and the CH 4 equivalence ratio is evaluated. Additionally, ReaxFF-MD simulations are employed to trace the evolution of key products and reaction pathways during the CH 4 -C 2 HF 5 reaction process, thereby constructing the mechanism of C 2 HF 5 ’s effect. The results indicate that the explosion pressure of CH 4 mixtures with equivalence ratios ranging from 0.6 to 1.4 increases initially and then decreases as the volume fraction of C 2 HF 5 increases. C 2 HF 5 exhibits a promoting effect on explosion pressure, with its suppressive effect being more pronounced in oxygen-poor environments. Based on this, the reaction process of CH 4 with 2 % and 8 % C 2 HF 5 was simulated using the reaction force field simulation, yielding an activation energy of 180.280 kJ/mol for the CH 4 reaction. The significant amount of ·OH generated during the reaction of 2 % C 2 HF 5 with H· and H 2 O in the system is the intrinsic mechanism that promotes the increase in explosion intensity. In contrast, the 8 % C 2 HF 5 reaction consumes more heat and active radicals, while the large amounts of non-flammable gases such as COF 2 produced lower the oxygen content in the system, making the CH 4 reaction more difficult. This leads to an increase in activation energy by 22.168 kJ/mol, thereby achieving explosion suppression.