Experimental and kinetic analysis of laminar flame speed in hydrogen-enriched highly branched iso-alkanes: A comparison of iso-octane and iso-dodecane

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-09-26 DOI:10.1016/j.combustflame.2025.114506

Congjie Hong , Jiabiao Zou , Yada Leo , Janardhanraj Subburaj , Ayman M. Elbaz , William L. Roberts , Zuohua Huang , Yingjia Zhang , Aamir Farooq

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引用次数: 0

Abstract

Highly branched alkanes, critical components of sustainable aviation fuels (SAFs), significantly influence the efficiency and emissions of aircraft engines. With the increasing global demand for low-carbon aviation fuels, a deeper understanding of the combustion kinetics of highly branched alkanes is essential for optimizing fuel design and reducing carbon emissions. In this study, the laminar flame speeds of iso-octane (2,2,4-trimethyl pentane), iso-dodecane (2,2,4,6,6-pentamethylheptane; PMH) and their blends with hydrogen were investigated over equivalence ratios ranging 0.7 to 1.4, pressures from 0.5 to 1.0 bar, and temperatures of 353 and 395 K. Results indicate that iso-octane exhibits consistently higher laminar flame speeds than PMH across all equivalence ratios, with a more pronounced difference under lean conditions. Reaction pathway analysis reveals that PMH generates a higher yield of dienes, which consume a substantial amount of H radicals in further reactions, resulting in chain inhibition and a reduction in overall flame propagation. In contrast, iso-octane predominantly produces tert‑butyl and iso-propyl radicals, which further decompose into H and iso-butene/propene, thereby enhancing flame propagation. Hydrogen blending enhances flame speeds for both fuels, with a more pronounced effect on iso-octane. This is mainly due to the increased concentrations of key radicals (H, O, and OH), which accelerate chain reactions. This study presents the first experimental dataset of PMH laminar flame speed, addressing a critical gap for validating chemical kinetic models and enhancing combustion simulations. Additionally, the findings provide valuable insights into the combustion behavior of highly branched alkanes in hydrogen-enriched environments, supporting the development of low-carbon, high-efficiency clean fuels.

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富氢高支化异构烷烃层流火焰速度的实验与动力学分析：异辛烷与异十二烷的比较

高支链烷烃是可持续航空燃料（SAFs）的关键成分，对飞机发动机的效率和排放有重大影响。随着全球对低碳航空燃料需求的不断增长，深入了解高支链烷烃的燃烧动力学对于优化燃料设计和减少碳排放至关重要。在本研究中，研究了异辛烷（2,2,4-三甲基戊烷）、异十二烷（2,2,4,6,6-五甲基庚烷；PMH）及其与氢的共混物的层流火焰速度，其当量比为0.7至1.4，压力为0.5至1.0 bar，温度为353和395 K。结果表明，在所有等效比下，异辛烷的层流燃烧速度始终高于PMH，在稀薄条件下差异更为明显。反应途径分析表明，PMH产生了更高的二烯产率，二烯在进一步的反应中消耗了大量的H自由基，导致链抑制和整体火焰传播的减少。相反，异辛烷主要产生叔丁基和异丙基自由基，这些自由基进一步分解为H和异丁烯/丙烯，从而增强火焰的传播。混合氢提高了两种燃料的燃烧速度，对异辛烷的影响更明显。这主要是由于关键自由基（H， O和OH）的浓度增加，加速了链式反应。本研究提出了PMH层流火焰速度的第一个实验数据集，解决了验证化学动力学模型和增强燃烧模拟的关键空白。此外，这些发现为高支链烷烃在富氢环境中的燃烧行为提供了有价值的见解，支持了低碳、高效清洁燃料的开发。

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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.