Effect of the initial temperature and composition of a hot transient jet on the ignition of H{sub 2}-air-diluent mixtures
- Centre National de la Recherche Scientifique, Orleans (France). Lab. de Combustion et Systemes Reactifs
An original facility has been built, which consists of a shock tube connected to a combustion chamber via an injector, in order to analyze the ignition of a combustible mixture by a subsonic hot gas jet. Using this technique, it is shown that the stagnation temperature, just prior to ejection, of an H{sub 2}-Ar mixture heated behind a reflected shock wave between 750 and 3000 K is the main parameter for igniting H{sub 2}-air-diluent (CO{sub 2} or H{sub 2}O) mixtures. The minimum stagnation temperature to ignite an H{sub 2}-air mixture is approximately equal to the self-ignition temperature of this mixture. If CO{sub 2} or H{sub 2}O is added to the combustible mixture, the minimum stagnation temperature must be increased. Beyond the critical diluent concentration, the mixture cannot be ignited whatever the initial jet temperature is. The temperature corresponding to the critical composition is called the minimum critical temperature. Under these conditions, the ignition limits by a hot jet constituted of a shock-heated H{sub 2}-Ar mixture have been determined for H{sub 2}-air-CO{sub 2} and H{sub 2}-air-H{sub 2}O mixtures. The conditions for which ignition is no longer observed for an H{sub 2}-air-H{sub 2}O mixture are the following: equivalence ratio {phi} = 0.55, initial temperature and pressure, respectively, of 403 K and 100 kPa, and mol% H{sub 2}O = 48. The ignition limits are compared with the classical flammability limits. The influence of the composition of the hot gas jet on the ignition limits of H{sub 2}-air-H{sub 2}O mixtures has been analyzed and discussed. The present result provide a new assessment, particularly important for nuclear reactor safety.
- OSTI ID:
- 93305
- Report Number(s):
- CONF-940711-; TRN: 95:018348
- Resource Relation:
- Conference: 25. international symposium on combustion, Irvine, CA (United States), 31 Jul - 5 Aug 1994; Other Information: PBD: 1994; Related Information: Is Part Of Twenty-fifth symposium (international) on combustion; PB: 1838 p.
- Country of Publication:
- United States
- Language:
- English
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