{"title":"甲烷/氨气/氮气与高温空气非预混逆流火焰的消光极限和自由基指数","authors":"Yuki Murakami, Takuya Tezuka, Hisashi Nakamura","doi":"10.1016/j.combustflame.2024.113540","DOIUrl":null,"url":null,"abstract":"<div><p>The extinction limits of non-premixed counterflow flames of methane (CH<sub>4</sub>)/ammonia (NH<sub>3</sub>)/nitrogen (N<sub>2</sub>) versus high-temperature air (<em>T</em><sub>Air</sub> = 700 K and 1000 K) were investigated both experimentally and numerically. Extinction stretch rates of non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures decreased greatly as the ammonia mixing ratio increased. Recent chemical kinetic models could well predict measured extinction limits of non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures, especially for <em>T</em><sub>Air</sub> = 1000 K. Chemical kinetic analyses indicated that the nature of NH<sub>3</sub> consuming active radicals but not regenerating them through its oxidation is the primary reason for the drastic decreases in extinction stretch rates of non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures. Furthermore, the combined metric of the transport weighted enthalpy (<em>TWE</em>) and the radical index (<em>RI</em>) is introduced for non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures. The OH-radical index (<em>RI</em><sub>OH</sub>), previously used in the combined metric for extinction limits of non-premixed counterflow flames of large hydrocarbons, expresses linear relationships with extinction limits for both <em>T</em><sub>Air</sub> conditions. According to further investigations on heat releases from individual reactions, the contribution to heat releases from a reaction involving O radicals, i.e., CH<sub>3</sub> + O ⇄ CH<sub>2</sub>O + H, becomes large in addition to reactions involving OH radicals, i.e., CO + OH ⇄ CO<sub>2</sub> + H and H<sub>2</sub> + OH ⇄ H + H<sub>2</sub>O. Based on the analyses, a new radical index based on the combination of OH and O radicals (<em>RI</em><sub>OH&O</sub>) is proposed. The <em>RI</em><sub>OH&O</sub> better expresses the linear relationship between extinction limits and the combined metric of <em>RI</em><sub>OH&O</sub> and <em>TWE</em>.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":null,"pages":null},"PeriodicalIF":5.8000,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0010218024002499/pdfft?md5=30f6fc89999ac63b449dd015a6b0b595&pid=1-s2.0-S0010218024002499-main.pdf","citationCount":"0","resultStr":"{\"title\":\"The extinction limits and the radical index of non-premixed counterflow flames of methane/ammonia/nitrogen versus high-temperature air\",\"authors\":\"Yuki Murakami, Takuya Tezuka, Hisashi Nakamura\",\"doi\":\"10.1016/j.combustflame.2024.113540\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The extinction limits of non-premixed counterflow flames of methane (CH<sub>4</sub>)/ammonia (NH<sub>3</sub>)/nitrogen (N<sub>2</sub>) versus high-temperature air (<em>T</em><sub>Air</sub> = 700 K and 1000 K) were investigated both experimentally and numerically. Extinction stretch rates of non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures decreased greatly as the ammonia mixing ratio increased. Recent chemical kinetic models could well predict measured extinction limits of non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures, especially for <em>T</em><sub>Air</sub> = 1000 K. Chemical kinetic analyses indicated that the nature of NH<sub>3</sub> consuming active radicals but not regenerating them through its oxidation is the primary reason for the drastic decreases in extinction stretch rates of non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures. Furthermore, the combined metric of the transport weighted enthalpy (<em>TWE</em>) and the radical index (<em>RI</em>) is introduced for non-premixed counterflow flames of CH<sub>4</sub>/NH<sub>3</sub> mixtures. The OH-radical index (<em>RI</em><sub>OH</sub>), previously used in the combined metric for extinction limits of non-premixed counterflow flames of large hydrocarbons, expresses linear relationships with extinction limits for both <em>T</em><sub>Air</sub> conditions. According to further investigations on heat releases from individual reactions, the contribution to heat releases from a reaction involving O radicals, i.e., CH<sub>3</sub> + O ⇄ CH<sub>2</sub>O + H, becomes large in addition to reactions involving OH radicals, i.e., CO + OH ⇄ CO<sub>2</sub> + H and H<sub>2</sub> + OH ⇄ H + H<sub>2</sub>O. Based on the analyses, a new radical index based on the combination of OH and O radicals (<em>RI</em><sub>OH&O</sub>) is proposed. The <em>RI</em><sub>OH&O</sub> better expresses the linear relationship between extinction limits and the combined metric of <em>RI</em><sub>OH&O</sub> and <em>TWE</em>.</p></div>\",\"PeriodicalId\":280,\"journal\":{\"name\":\"Combustion and Flame\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":5.8000,\"publicationDate\":\"2024-06-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.sciencedirect.com/science/article/pii/S0010218024002499/pdfft?md5=30f6fc89999ac63b449dd015a6b0b595&pid=1-s2.0-S0010218024002499-main.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Combustion and Flame\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0010218024002499\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ENERGY & FUELS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Combustion and Flame","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0010218024002499","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
引用次数: 0
摘要
通过实验和数值计算研究了甲烷(CH4)/氨(NH3)/氮(N2)与高温空气(TAir = 700 K 和 1000 K)非预混逆流火焰的消光极限。随着氨气混合比的增加,CH4/NH3 混合物的非预混合逆流火焰的熄灭伸展率大大降低。最新的化学动力学模型可以很好地预测 CH4/NH3 混合物非预混合逆流火焰的消光极限,特别是在 TAir = 1000 K 的情况下。化学动力学分析表明,NH3 消耗活性自由基而不是通过其氧化作用再生活性自由基的性质是 CH4/NH3 混合物非预混合逆流火焰消光伸展率急剧下降的主要原因。此外,还针对 CH4/NH3 混合物的非预混合逆流火焰引入了传输加权焓(TWE)和自由基指数(RI)的组合指标。之前用于大碳氢化合物非预混逆流火焰消光极限的组合指标中的羟基-自由基指数(RIOH)与 TAir 两种条件下的消光极限均呈线性关系。根据对单个反应释放热量的进一步研究,除了涉及 OH 自由基的反应(即 CO + OH ⇄ CO2 + H 和 H2 + OH ⇄ H + H2O)外,涉及 O 自由基的反应(即 CH3 + O ⇄ CH2O + H)对释放热量的贡献也变得很大。根据分析结果,提出了一种基于 OH 和 O 自由基组合的新自由基指数(RIOH&O)。RIOH&O 更好地表达了消光极限与 RIOH&O 和 TWE 组合指标之间的线性关系。
The extinction limits and the radical index of non-premixed counterflow flames of methane/ammonia/nitrogen versus high-temperature air
The extinction limits of non-premixed counterflow flames of methane (CH4)/ammonia (NH3)/nitrogen (N2) versus high-temperature air (TAir = 700 K and 1000 K) were investigated both experimentally and numerically. Extinction stretch rates of non-premixed counterflow flames of CH4/NH3 mixtures decreased greatly as the ammonia mixing ratio increased. Recent chemical kinetic models could well predict measured extinction limits of non-premixed counterflow flames of CH4/NH3 mixtures, especially for TAir = 1000 K. Chemical kinetic analyses indicated that the nature of NH3 consuming active radicals but not regenerating them through its oxidation is the primary reason for the drastic decreases in extinction stretch rates of non-premixed counterflow flames of CH4/NH3 mixtures. Furthermore, the combined metric of the transport weighted enthalpy (TWE) and the radical index (RI) is introduced for non-premixed counterflow flames of CH4/NH3 mixtures. The OH-radical index (RIOH), previously used in the combined metric for extinction limits of non-premixed counterflow flames of large hydrocarbons, expresses linear relationships with extinction limits for both TAir conditions. According to further investigations on heat releases from individual reactions, the contribution to heat releases from a reaction involving O radicals, i.e., CH3 + O ⇄ CH2O + H, becomes large in addition to reactions involving OH radicals, i.e., CO + OH ⇄ CO2 + H and H2 + OH ⇄ H + H2O. Based on the analyses, a new radical index based on the combination of OH and O radicals (RIOH&O) is proposed. The RIOH&O better expresses the linear relationship between extinction limits and the combined metric of RIOH&O and TWE.
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.