Extinguishment of hydrogen laminar diffusion flames by water vapor in a cup burner apparatus |
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| Institution: | 1. State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, China;2. School of Civil Engineering, Zhengzhou University, Zhengzhou, Henan 450001, China;1. Aix-Marseille Université, IUSTI/UMR CNRS 7343, 5 rue E. Fermi, Marseille Cedex 13 13453, France;2. Departamento de Industrias, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chile;1. Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA;2. NASA Glenn Research Center, Cleveland, OH 44135, USA;3. Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093, USA;1. Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Avenue Cleveland, Cleveland, OH 44106, USA;2. Innovative Scientific Solutions, Inc., Dayton, OH 45440, USA;3. National Institute of Standards and Technology, Gaithersburg, MD 20899, USA |
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| Abstract: | Transient computations with full hydrogen chemistry were performed to reveal the flame structure and extinguishment process of co-flow, hydrogen diffusion flame suppressed by water vapor. As the concentration of water vapor was increased, the flame detached away from the burner brim and formed an edge flame at the flame base. Water vapor showed larger chemical inhibition effect than nitrogen when extinguishing hydrogen flame, which was attributed to its enhanced third body effect in the reaction H + O2 + M = HO2 + M. The minimum extinguishing concentration (MEC) of water vapor and nitrogen was predicted by Senecal formula and perfectly stirred reactor (PSR) model respectively. The MECs predicted by PSR model agree with the MECs calculated by Fluent, which shows that 1) the flame extinction is controlled by the flame base, and 2) radiation absorption is negligible. The measured MECs are in a reasonable agreement with the values calculated by Fluent, which demonstrates the accuracy of the CFD model. A simple model was used to investigate the relative importance of extinguishing mechanisms of water vapor. The results show that in a co-flow configuration the thermal cooling and chemical inhibition effect are the main extinguishing mechanisms in suppressing hydrogen diffusion cup burner flame. |
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| Keywords: | Hydrogen safety Diffusion flame Water vapor Nitrogen Flame suppression |
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