Extinguishment of counter-flow diffusion flame by water mist derived from aqueous solutions containing chemical additives

A comparative study on the suppression efficiency of different water mist additives was conducted in a counter-flow flame apparatus. The introduction of 1mL/min ultrapure water mist reduced the critical stretch rate by 14%. The chemical additives could improve the suppression efficiency of water mist except FeSO4 and H3PO4. Their suppression efficiency could be generally sorted in a descending order: organic alkali metal salts (K2C2O4, C2H3KO2), inorganic alkali metal salts (KCl, KHCO3, K3PO4), phosphorus-containing compounds (K3PO4, NH4H2PO4, H3PO4), and inorganic ferrous compounds (FeCl2, FeSO4). The morphology of the particles deviated from the previous sphere shape assumptions. It is assumed that the efficiency of chemical additives in suppressing highly stretched diffusion can depend on the following factors: (1) the chemical nature of the additives, (2) the residence time controlled by the flow conditions, and (3) the residual particles formed by the additive-containing water mist.