Study of low-to-moderate temperature oxidation of 1,2,4-trimethylbenzene/n-heptane blends

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-05-10 DOI:10.1016/j.combustflame.2025.114223

S. Hossain , M. Abdulrahman , P.T. Lynch , EricK. Mayhew , K. Brezinsky

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Abstract

Single-pulse shock tube experiments were performed at a nominal pressure of 50 atm and a reaction time of 13 milliseconds (ms) over a temperature range of 700–1400 K to study the oxidation speciation of a 1,2,4-trimethylbenzene/n-heptane (HTMB) blend. The oxidation experiments were conducted across a range of equivalence ratios (φ = 2.0, 1.0, 0.50, and 0.25). Gas chromatography (GC) was used to quantitatively and qualitatively analyze the post-shock gases, providing speciation data on oxidation products as a function of temperature. The speciation results were simulated using the CRECK (CRECK_2003_TOT_HT_LT), LLNL, and Zeng_Xie mechanisms. All three mechanisms simulated the experimental speciation data well, with the CRECK mechanism demonstrating the best overall agreement. At lower temperatures (∼740 K) and under fuel-lean conditions (φ = 0.25), negative temperature coefficient (NTC) behavior was observed in both the reactants and the oxidation products, specifically in alkenes and aldehydes. Rate of production, sensitivity, and reaction path analyses were also conducted to investigate the reactions affecting the oxidation process. The primary reaction channel that initiates the oxidation process is H-abstraction by OH radicals, along with an additional H-abstraction reaction channel by HO₂ radicals, particularly under fuel-lean conditions. The formation of trimethylbenzyl radicals (RC₉H₁₁) from 1,2,4-trimethylbenzene decomposition inhibits the oxidation process, slowing down radical generation and, consequently, affecting the reactivity of n-heptane and the overall HTMB blend.

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1,2,4-三甲苯/正庚烷共混物的低温氧化研究

以1,2,4-三甲基苯/正庚烷（HTMB）共混物为研究对象，在标称压力为50 atm，反应时间为13毫秒（ms），温度范围为700 ~ 1400 K的单脉冲激波管实验条件下，研究了其氧化形态。氧化实验在φ = 2.0, 1.0, 0.50和0.25等比值范围内进行。气相色谱（GC）用于定量和定性分析后的冲击气体，提供氧化产物的形态数据作为温度的函数。采用CRECK （crec_2003_tot_ht_lt）、LLNL和增解机制对物种形成结果进行了模拟。所有三种机制都能很好地模拟实验物种形成数据，其中CRECK机制表现出最好的总体一致性。在较低温度（~ 740 K）和低燃料条件（φ = 0.25）下，在反应物和氧化产物中都观察到负温度系数（NTC）行为，特别是在烯烃和醛中。对反应的产率、灵敏度和反应路径进行了分析，探讨了反应对氧化过程的影响。启动氧化过程的主要反应通道是OH自由基的吸氢反应通道，以及HO 2自由基的吸氢反应通道，特别是在燃料稀薄的条件下。1,2,4-三甲基苯分解形成的三甲基苯自由基（RC₉H₁₁）抑制了氧化过程，减缓了自由基的产生，从而影响了正庚烷和整个HTMB混合物的反应性。

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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.