Exploring high-temperature interaction between NH3/H2 blends and NO in laminar flame propagation: Insight into the competition between H-NO and NHx-NO mechanisms

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-04-25 DOI:10.1016/j.combustflame.2025.114181

Jianguo Zhang , Jun Fang , Tianyou Lian , Sibo Han , Jiabiao Zou , Wei Li , Yuyang Li

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引用次数: 0

Abstract

Ammonia (NH₃) co-firing with hydrogen (H₂) and NH₃ pre-cracking are widely adopted combustion enhancement strategies for NH₃ applications in practical combustion devices, raising a growing need to understand the high-temperature interaction of NH₃/H₂ blends and nitric oxide (NO), which is critical for NO reduction mechanism. In this work, the oxygen-free outwardly propagating spherical flame method is used to investigate the laminar flame propagation of NH₃/H₂/NO and NH₃/H₂/NO/N₂ mixtures at 1 atm and 298 K. A non-monotonic behavior of laminar burning velocities (LBVs) of NH₃/H₂/NO mixtures with increasing H₂ content is observed. A kinetic model of NH₃/H₂/NO combustion is constructed and validated against the new data in this work and previous data in literature. Rate of production analysis, sensitivity analysis and updated fictitious diluent gas method are adopted to reveal the critical combustion chemistry in NH₃/H₂/NO flames with insight into the competition between H-NO and NH_x-NO mechanisms. The non-monotonic variation of LBVs can be attributed to the competition between thermal effect and chemical effect. The controlling mechanism of NO reduction and the sensitive mechanism of laminar flame propagation are revealed to be strongly dependent on fuel compositions and equivalence ratios. H-NO and NH₂-NO mechanisms both play important roles in lean NH₃/NO flame. With the increase of H₂ content, the contributions of NH_x-NO mechanisms to NO reduction and the sensitivity coefficients decrease, while the contribution of H-NO mechanism follows a reverse order. Under rich conditions, NH₂-NO mechanism has exclusively high sensitivity coefficients in NH₃/NO flames, while its rapidly decreasing significance and the increasing importance of H-NO mechanism with the increasing H₂ content leads to transitions in the most sensitive mechanism of laminar flame propagation at 0.5-0.7 H₂ contents. Compared with H-NO and NH₂-NO mechanisms, the NH-NO mechanism has negligible sensitivity coefficients, because its key reactions are mainly chain propagation reactions.

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探索NH3/H2共混物与NO在层流火焰传播中的高温相互作用：H-NO和NHx-NO竞争机制的洞察

氨（NH3）与氢（H2）共烧和NH3预裂化是实际燃烧装置中广泛采用的增强燃烧策略，因此越来越需要了解NH3/H2混合物与一氧化氮（NO）的高温相互作用，这对NO还原机制至关重要。本文采用无氧向外传播球形火焰法研究了NH3/H2/NO和NH3/H2/NO/N2混合物在1atm和298 K下的层流火焰传播。NH3/H2/NO混合物的层流燃烧速度随H2含量的增加呈非单调变化。建立了NH3/H2/NO燃烧的动力学模型，并根据本文的新数据和文献数据进行了验证。采用生成速率分析、敏感性分析和更新的虚拟稀释气体法揭示了NH3/H2/NO火焰的临界燃烧化学，并深入了解了H-NO和NHx-NO的竞争机制。LBVs的非单调变化可归因于热效应和化学效应的竞争。NO还原的控制机制和层流火焰传播的敏感机制强烈依赖于燃料成分和当量比。H-NO和NH2-NO机制在贫NH3/NO火焰中均起重要作用。随着H2含量的增加，NHx-NO机制对NO还原的贡献和敏感性系数减小，而H-NO机制的贡献则相反。在丰富条件下，NH2-NO机制在NH3/NO火焰中具有高敏感系数，而随着H2含量的增加，NH2-NO机制的重要性迅速降低，H-NO机制的重要性增加，导致在H2含量为0.5 ~ 0.7时层流火焰传播最敏感的机制发生转变。与H-NO和NH2-NO机制相比，NH-NO机制的敏感性系数可以忽略不计，因为其关键反应主要是链传播反应。

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.