Chemical Kinetic Studies of Reactions Relevant to Muzzle Flash and Afterburning Suppression by Potassium and Sodium Compounds

摘要

Rate constants have been determined for gas phase reactions of alkali species which are relevant to flame suppression chemistry by sodium and potassium compounds. Sources and detection methods for gas phase molecular alkali species kO, kO2, Na, NaO2 and NaOH have been developed and applied to kinetic studies of these species using a high temperature fast flow reactor. Rate constants for the recombination reactions of alkali atoms with molecular oxygen, K + O2 + M yields KO2 + M and Na + O2 + M yields NaO2 + M, have been measured as a function of temperature from 300 to 700 K. Laser induced fluorescence is used to monitor the disappearance of Na or K as a function of O2 and M. The reactions of NaOH, NaO2 and NaO with HCl at 300 K are found to proceed at their gas kinetic limits to form NaCl. Other reactions studied include: NaOH + H yield Na + H2O, NaCl + H yields Na + HCl and both Na and K with H2O2. KOH has been detected in the gas phase by infrared absorption at 424/cm using a tunable diode laser. This method has wide applicability for direct detection of a number of molecular alkali species for laboratory kinetic studies and for in situ combustion flame diagnostics. Theoretical sensitivity estimates are calculated for KOH, KO2, KO, NaOH, NaO2, NaO and NaCl for both high temperature, atmospheric pressure and low pressure flow tube conditions.