Suppression of premixed flames with inert particles

Dispersal of inert particles on a flame front is one of the techniques employed to suppress explosions. The current study investigates the influence of micron-sized (75-90 μm) inert (sand) particles on the laminar burning velocity of methane-air premixtures of different equivalence ratios (0.9-1.2) and reactant temperatures (297, 350, 400 K) using a Bunsen-burner type experimental apparatus. When an inert particle interacts with the flame zone, it extracts energy from the flame, thereby acting like a heat sink and hence reducing the flame temperature. Results show that for sand particle size in the range of 75-90 μm, a concentration of 380-520 g/m3 is necessary for extinction of a methane-air flame at ambient temperature. An increase in reactant temperature reduces the heat-sink effect necessitating a higher concentration of sand to extinguish the flame. A mathematical model is developed to generalize the results and make them applicable to a wide range of parameters.