Effects of nitrogen and carbon dioxide on hydrogen explosion behaviors near suppression limit

• Published in: Journal of loss prevention in the process industries Vol. 67; p. 104228
• Main Authors: Yan, Caicai, Bi, Mingshu, Li, Yanchao, Gao, Wei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2020
• Subjects: Buoyancy instability; Hydrogen explosion behaviors; Suppression limit; Suppression mechanism; Suppression mechanism; Suppression limit; Hydrogen explosion behaviors; Buoyancy instability
• ISSN: 0950-4230
• DOI: 10.1016/j.jlp.2020.104228

By varying inert gas content, equivalence ratio and initial pressure, this study is aimed at investigating flame propagation behaviors and explosion pressure characteristics near suppression limit. For carbon dioxide, the weakest flame floating phenomenon is observed at Φ = 1.5 and the buoyant instability is enhanced when the equivalent ratio deviates to the rich and lean sides. For nitrogen, the buoyant instability decreases with increasing equivalent ratio. Both maximum explosion pressure and maximum pressure rise rate increase firstly and then decrease with the increase of equivalence ratio, and they decrease significantly with increasing content of carbon dioxide and nitrogen. For carbon dioxide, the critical suppression ratio of Φ = 0.6, 0.8, 1.0, 1.5 and 2.0 is 7.50, 7.18, 5.74, 3.83, and 2.87. For nitrogen, the critical suppression ratio of Φ = 0.6, 0.8, 1.0, 1.5 and 2.0 is 15.83, 11.87, 9.50, 6.33 and 4.75. Compared to nitrogen, the carbon dioxide is more effective on suppressing hydrogen explosion pressure. The adiabatic flame temperature, thermal diffusivity and mole fraction of active radicals continue to decrease with increasing content of carbon dioxide and nitrogen, which contributes to the decrease of laminar burning velocity. •Flame behavior under buoyancy instability is analyzed.•The critical suppression ratio of carbon dioxide and nitrogen is obtained.•The suppression mechanism of carbon dioxide and nitrogen is revealed.