Investigation on the suppression effect of high momentum C6F12O (Novec-1230) flow on hydrogen jet flame

Abstract

This work investigates the suppression effect of Novec-1230 on H2 jet flame. The suppressants are motivated by N2 flow to get higher momentum and approach the reaction kernel at flame base. The flame area with Novec-1230 is always smaller than that with water mist at the same condition. Novec-1230 exhibits better suppression effect on reaction kernel. The higher-momentum jet flame is more difficult to be suppressed. This is because that the higher-momentum flame makes the suppressant approach the reaction kernel more difficult. In addition, the high N2 flow rate containing suppressant could destroy flame temperature structure and decrease it. Results inferred that the temperature of flame with Novec-1230 is higher than that with water mist. Moreover, the lower minimum extinguishing time indicates that the suppression efficiency of Novec-1230 is better than that of water mist. The jet flame is extinguished only when H2 flow rate is low and N2 flow rate is high. There are two reasons: one is that the higher-momentum jet flame prevents suppressants to enter flame core. The other one is that the burner nozzle is heated to as igniting source during suppression progress. Furthermore, the burning velocity, adiabatic flame temperature, heat production and free radicals are investigated theoretically at Φ = 1.6, 1.0, 0.8 and 0.6. Results indicate that the burning velocity with Novec-1230 is much lower than that with water mist. The adiabatic flame temperature, heat production and free radicals increase firstly and then decrease with Novec-1230 addition at lean flame.