Differences between the effects of NH3 cracking and H2 addition on the flame propagation of NH3/DME/Air mixtures: An experimental and kinetic study

IF 5.9 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2026-04-01 Epub Date: 2026-02-09 DOI:10.1016/j.combustflame.2026.114858

Huizhen Li , Huahua Xiao

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引用次数: 0

Abstract

Co-firing with other highly active fuels and partially dissociated ammonia (NH₃) are the two attractive ways to enhance the combustion properties of NH₃. In view of the ammonia/dimethyl ether/hydrogen (NH₃/DME/H₂) mixed combustion, it is necessary to explore the influence of different H₂ sources in blends on combustion characteristics. This work conducted experiments and simulations to study the differences in flame propagation between NH₃/DME/Air mixtures with partially dissociated NH₃ and those with H₂ addition. The flame morphology and laminar burning velocity (S_L) of 80%NH₃/20%DME/Air mixtures with various H₂ additions (X_H2 = 0-0.9) and NH₃ cracking ratios (γ = 0-0.9) were measured at equivalence ratios of ϕ = 0.7-1.7 and normal temperature/pressure (T_u = 298 K, P_u = 0.1 MPa) using the spherical constant-volume combustion approach. By comparing the change of instability evaluation parameters with increasing H₂ content, it can be inferred that the more wrinkles caused by the increase of H₂ concentration are mainly due to the enhancement of hydrodynamic instability caused by the decreasing flame thickness, and the mixtures with H₂ addition are more prone to flame instability than those with partially dissociated NH₃. The results of the measured and predicted S_L show that the partially dissociated NH₃ in NH₃/DME/Air mixtures can promote combustion to a higher extent than adding H₂ directly due to the more H₂ produced as γ = X_H2, and the degree is more serious with the increase of H₂ content. The results of decoupling thermal effect and chemical effect show that S_L is mainly dominated by the chemical effect. Compared to the mixtures with H₂ addition, the mixtures with partially dissociated NH₃ have a stronger promoting effect on chemical effect, while a weaker effect on thermal effect. In addition, the combustion processes of these two kinds of mixtures are similar through sensitivity and reaction pathways analysis.

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NH3裂解与H2加入对NH3/二甲醚/空气混合物火焰传播影响的差异：实验与动力学研究

与其他高活性燃料共烧和部分解离氨（NH3）是提高NH3燃烧性能的两种有吸引力的方法。针对氨/二甲醚/氢（NH3/二甲醚/H2）混合燃烧，有必要探讨混合物中不同H2源对燃烧特性的影响。本文通过实验和模拟研究了部分解离NH3与添加H2的NH3/二甲醚/空气混合物在火焰传播中的差异。在φ = 0.7 ~ 1.7的等效比和常温/常压（Tu = 298 K, Pu = 0.1 MPa）条件下，采用球形等体积燃烧法测量了不同H2添加量（XH2 = 0 ~ 0.9）和NH3裂解比（γ = 0 ~ 0.9）的80%NH3/20%二甲醚/空气混合物的火焰形态和层状燃烧速度（SL）。通过比较不稳定性评价参数随H2含量增加的变化，可以推断H2浓度增加引起的褶皱增多主要是由于火焰厚度减小引起的流体动力不稳定性增强，添加H2的混合物比部分解离NH3的混合物更容易发生火焰不稳定性。结果表明，NH3/二甲醚/空气混合物中部分解离的NH3比直接加入H2对燃烧的促进作用更大，因为其以γ = XH2的形式生成的H2更多，且随着H2含量的增加，促进作用更强。热效应和化学效应的解耦结果表明，热效应主要以化学效应为主。与加入H2的混合物相比，加入部分解离NH3的混合物对化学效应的促进作用更强，而对热效应的促进作用较弱。此外，通过灵敏度和反应路径分析，两种混合物的燃烧过程相似。

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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.