Search of Suitable Halon 1301-Like Fire Suppressants Based on Flame Inhibition Mechanism Understanding

摘要

Halon 1301 (CF3Br) had been widely used as a fire extinguisher for many years due to itsrnunique properties including high extinguishing efficiency at low concentrations, high dispersionrncapabilities, and storage stability, among others. Unfortunately, CF3Br and other halogenated firernsuppressants have been restricted by the Montreal Protocol due to their high ozone depletingrnpotential. This restriction has led to the necessity to find cleaner alternatives with similar, Halonrn1301-like capabilities. Despite all the scientific efforts made during the last few decades, nornsingle suitable Halon 1301 substitute has been found. A more likely approach to overcome thisrnissue is to study a variety of novel choices that can be used on specific situations. Identificationrnof these alternatives requires a systematic methodology based on the understanding of the flamerninhibition mechanisms that could address this search in promising directions. To this end, thernpresent work presents a methodology to investigate fundamental phenomena involved in therncombustion inhibition mechanism of CF3Br by using detailed chemical kinetics which have beenrnexperimentally validated. Specialized combustion equipment, including a high-pressure shockrntube and a flame speed bomb, are used to obtain important parameters including ignition delayrntime, OH* time histories, and flame speeds which are also employed as metrics for modelrnvalidation. In particular, laminar flame speed is considerably important since it represents arnfundamental property of the reacting mixture and provides a tool for deeper flame inhibitionrnanalysis to evaluate thermal and chemical inhibition contributions and saturation effects.rnSensitivity analysis is performed to generate valuable information regarding key elementaryrnreactions that limit and control flame inhibition behavior. Halon 1301 may be unique in itsrnability to modify both the chemical kinetics and thermal properties of a reacting system. With arnfundamental understanding of the chemical and thermal advantages of CF_3Br as a firernsuppressant, the same fundamental tools can be employed to test for similar attributes inrncandidate compounds. This approach provides a guide for identification of novel, chemicallyrnactive inhibitors which behave similar to CF3Br but can be significantly less harmful to thernenvironment.