Search of suitable Halon 1301-like fire suppressants based on flame inhibition mechanism understanding
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Halon 1301 (CF 3Br) had been widely used as a fire extinguisher for many years due to its unique properties including high extinguishing efficiency at low concentrations, high dispersion capabilities, and storage stability, among others. Unfortunately, CF 3Br and other halogenated fire suppressants have been restricted by the Montreal Protocol due to their high ozone depleting potential. This restriction has led to the necessity to find cleaner alternatives with similar, Halon 1301-like capabilities. Despite all the scientific efforts made during the last few decades, no single suitable Halon 1301 substitute has been found. A more likely approach to overcome this issue is to study a variety of novel choices that can be used on specific situations. Identification of these alternatives requires a systematic methodology based on the understanding of the flame inhibition mechanisms that could address this search in promising directions. To this end, the present work presents a methodology to investigate fundamental phenomena involved in the combustion inhibition mechanism of CF 3Br by using detailed chemical kinetics which have been experimentally validated. Specialized combustion equipment, including a high-pressure shock tube and a flame speed bomb, are used to obtain important parameters including ignition delay time, OH*time histories, and flame speeds which are also employed as metrics for model validation. In particular, laminar flame speed is considerably important since it represents a fundamental property of the reacting mixture and provides a tool for deeper flame inhibition analysis to evaluate thermal and chemical inhibition contributions and saturation effects. Sensitivity analysis is performed to generate valuable information regarding key elementary reactions that limit and control flame inhibition behavior. Halon 1301 may be unique in its ability to modify both the chemical kinetics and thermal properties of a reacting system. With a fundamental understanding of the chemical and thermal advantages of CF 3Br as a fire suppressant, the same fundamental tools can be employed to test for similar attributes in candidate compounds. This approach provides a guide for identification of novel, chemically active inhibitors which behave similar to CF 3Br but can be significantly less harmful to the environment.
