Quenching limits of inverse diffusion flames with enriched oxygen

Zhang, Yi; Sunderland, Peter B.

doi:10.1016/j.combustflame.2015.04.001

Cited by 4 publications

(2 citation statements)

References 32 publications

(45 reference statements)

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“…This phenomenon was also observed by Zhen at al. in a CoA burner setup, 32 when performing tests to estimate the quenching limits of methane, ethane, and ethylene IDFs with enriched oxygen. Apart from type A, all flame structures exhibit common characteristics.…”

Section: Resultsmentioning

confidence: 99%

Structure of CH₄–Air Inverse Diffusion Flames in a Multi-slit Burner

2021

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Inverse diffusion flame (IDF) configurations have shown to be robust to changes in fuel feed and combining desired characteristics of both diffusion and premixed flames. In this work, methane IDFs are characterized in a multi-slit burner. To this end, a multi-technique experiment with photography, particle image velocimetry, and flame chemiluminescence through spectroscopy is conducted. The flames studied encompass a range of conditions (0 ≤ V r ≤ 100) with laminar flow at two different power outputs (238 and 476 W). Four characteristic IDF structures were identified and denominated as types A, B, C, and D. Type A do not exhibit IDF-like characteristics and behave like normal diffusion flames. Types B, C, and D were found to exhibit a dual nature, with regions varying from a diffusion-like regime to a premixed-like regime. The velocity ratio V r was found to be the most important parameter when characterizing IDF, whereas the use of a global equivalence ratio ϕg can be misleading because it does not offer insight in actual reaction stoichiometry. Type C flames displayed ideal characteristics for the application in appliances as a result of its stability and absence of undesired yellow tips.

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Section: Resultsmentioning

confidence: 99%

Structure of CH₄–Air Inverse Diffusion Flames in a Multi-slit Burner

2021

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“…Additionally, the IDF existed in various engineering sceneries of power generation and fire safety. For instance, in many engines or staged combustion systems, the injection of central air into annular fuel streams can help to minimize the oxidation of combustor walls; , the leakage of enriched oxygen from the firefighter’s breathing equipment into an unventilated fire field would introduce a hazard in terms of the IDF geometry . Hence, our knowledge about the IDF combustion characteristics is of fundamental and practical importance in combustion and fire safety sciences (e.g., designing the advanced engines and high-efficiency extinguishment devices).…”

Section: Introductionmentioning

confidence: 99%

Comparative Study on the Dimethyl Ether Combustion Characteristics in Normal and Inverse Diffusion Spherical Flame Geometries

et al. 2020

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This paper makes a comparative study on the normal diffusion flame (NDF) and inverse diffusion flame (IDF) characteristics of dimethyl ether (DME) in microgravitational spherical diffusion flame geometry by simulations with detailed fuel chemistry and a transport model. It is found that there always existed two combustion modes (i.e., hot flame and cool flame) in either NDF or IDF condition. The combustion progress of hot flames was controlled by diffusive mixing, while that of cool flames was controlled by low-temperature competing kinetics. The cool-flame structure dynamics were far away from the chemical equilibrium. The low-temperature branching rate of DME was positively dependent on the oxygen level, while its termination rate was enhanced with the increasing temperature. Being rather distinct from the NDF counterpart, DME IDFs had the oxygen-enriched combustion feature in either hot- or cool-flame condition. Furthermore, DME hot-flame extinction was induced by thermal radiative loss, while the cool-flame extinction was induced especially by the decrease of the low-temperature branching rate. Compared with hot NDFs, it would be of less effectiveness to control the hot IDF combustion process by positive measures. However, combustion in the latter configuration was much more stable than the former. In either NDF or IDF geometry, the cool-flame chemistry could help to extend the fuel flammability range considerably, and the two-reaction-zone structure of cool flame was responsible for cool-flame stability. In addition, the IDFs had much better ignition performance than the NDF counterpart.

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