Combustion and Flame最新文献

{"title":"Continuous combustion of ammonia in a bubbling fluidized bed: Experimental and simulation study","authors":"Suyang Pan ,&nbsp;Jiliang Ma ,&nbsp;Xiaoping Chen ,&nbsp;Wenming Yang","doi":"10.1016/j.combustflame.2025.114343","DOIUrl":"10.1016/j.combustflame.2025.114343","url":null,"abstract":"<div><div>Ammonia, as a carbon-free energy carrier, supports the large-scale use of renewable energy, and its combustion is a key utilization pathway. This study examines the continuous combustion of ammonia in a bubbling fluidized bed using experiments and numerical simulations. The effects of equivalence ratio, fluidization velocity, secondary air injection location, and secondary oxygen ratio were investigated. Measurements focused on temperature distribution, ammonia conversion, and NO emissions, while simulations based on a two-fluid model revealed key reaction pathways. Results show that combustion mainly occurs in the dense phase. Lower equivalence ratios increase NO emissions, while fuel-rich conditions reduce NO but lower ammonia conversion. Higher fluidization velocity shortens residence time, reducing both NO emissions and conversion. The dense phase shows a catalytic effect on ammonia decomposition, affecting reactor temperature. At 900 °C, equivalence ratio of 1, and 40 % diluted oxygen, the main pathway from NH₃ to NO is: NH₃ → NH₂ → H₂NO → HNO → NO Notably, staged combustion, though typically used for NO reduction, increases NO and N₂O emissions in fluidized beds due to higher freeboard temperatures and enhanced conversion of NH₂/NH to NO.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114343"},"PeriodicalIF":5.8,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144587564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flame-wall interaction of thermodiffusively unstable hydrogen/air flames, Part I: Characterization of governing physical phenomena","authors":"Max Schneider,&nbsp;Hendrik Nicolai,&nbsp;Vinzenz Schuh,&nbsp;Matthias Steinhausen,&nbsp;Christian Hasse","doi":"10.1016/j.combustflame.2025.114320","DOIUrl":"10.1016/j.combustflame.2025.114320","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Hydrogen combustion systems operated under fuel-lean conditions offer great potential for low emissions. However, these operating conditions are also susceptible to intrinsic flame instabilities. Even though technical combustors are enclosed by walls that significantly influence the combustion process, intrinsic flame instabilities have mostly been investigated in canonical freely-propagating flame configurations unconfined by walls. This study aims to close this gap by investigating the flame-wall interaction of thermodiffusive unstable hydrogen/air flame through detailed numerical simulations in a two-dimensional head-on quenching configuration. It presents an in-depth qualitative and quantitative analysis of the quenching process, revealing the major impact factors of the instabilities on the quenching characteristics. The thermodiffusive instabilities result in lower quenching distances and increased wall heat fluxes compared to one-dimensional head-on quenching flames under similar operation conditions. The change in quenching characteristics is shown not to be driven by kinematic effects. Instead, the increased wall heat fluxes are caused by the enhanced flame reactivity of the unstable flame approaching the wall, which results from mixture variations associated with the instabilities. Overall, the study highlights the importance of studying flame-wall interaction in more complex domains than simple one-dimensional configurations, where such instabilities are inherently suppressed. Further, it emphasizes the need to incorporate local mixture variations induced by intrinsic combustion instabilities in combustion models for flame-wall interactions. In part II of this study, the scope is expanded to gas turbine and internal combustion engine relevant conditions through a parametric study, varying the equivalence ratio, pressure, and unburnt temperature.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;Novelty and Significance Statement&lt;/strong&gt;&lt;/div&gt;&lt;div&gt;This work presents novel simulations and in-depth analysis of flame-wall interaction (head-on quenching) of laminar thermodiffusively unstable hydrogen/air flames. Thermodiffusive instabilities are significant in technical combustion chambers enclosed by walls, such as gas turbines and internal combustion engines, particularly under lean conditions, where they raise safety concerns like flame flashback and increased thermal loads on walls. The study shows that these instabilities strongly affect flame-wall interaction, leading to smaller quenching distances and higher wall heat fluxes than in one-dimensional head-on quenching. Consequently, this work demonstrates that for flames susceptible to instabilities, such as lean hydrogen/air flames, one-dimensional head-on quenching simulations are inadequate for accurately determining wall heat fluxes and quenching distances. Additionally, this study highlights that differential diffusion effects induced by the intrinsic instabilities must be considered in combustion mod","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114320"},"PeriodicalIF":5.8,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Updated reaction rate rules for the construction and derivation of skeletal chemical mechanisms of lightly branched isoalkanes","authors":"Shuai Huang ,&nbsp;Yachao Chang ,&nbsp;Ying Huo ,&nbsp;Pengzhi Wang ,&nbsp;Yuxiang Zhu ,&nbsp;Jiaxin Liu ,&nbsp;Shangkun Zhou ,&nbsp;Jintao Chen ,&nbsp;Qingmiao Ding ,&nbsp;Henry J. Curran ,&nbsp;Ming Jia","doi":"10.1016/j.combustflame.2025.114340","DOIUrl":"10.1016/j.combustflame.2025.114340","url":null,"abstract":"<div><div><em>Iso</em>-alkanes are found in large quantities in both novel and conventional fuels. Accurate kinetic models for these fuels are essential for numerical simulations of combustion engines. However, existing chemical kinetic mechanisms are insufficient to fully elucidate the combustion chemistry of alkane isomers. Additionally, the influence of molecular structure differences between iso-alkanes, specifically differences in the position and number of methyl branches on their low-temperature oxidation pathways has not been comprehensively studied. The relationship between fuel properties, such as auto-ignition behavior and flame characteristics, and molecular structure is still not fully understood. The present study proposes updated reaction rate rules to establish skeletal kinetic mechanisms for monomethyl and dimethyl iso-alkanes with different positions of methyl substitution. Firstly, the important reaction classes from the sub-mechanisms of the hexane isomers are identified using reaction-class-based global sensitivity analysis. Subsequently, skeletal chemical mechanisms for 2-methyl and 3-methyl pentane are constructed, following a comparison of their critical reaction pathways. It is observed that the location of the methyl group significantly influences the positions of the critical H-atom abstraction reactions. This work further extends the study to dimethyl hexane isomers, by considering 2,2- and 2,3-dimethyl butane, and 2,3- and 2,4-dimethyl pentane. By integrating the monomethyl and dimethyl alkanes, reaction rate rules are updated for the construction of skeletal chemical mechanisms for larger iso-alkanes with similar molecular structures. Using reaction rate rules, skeletal chemical mechanisms of monomethyl and dimethyl iso-alkanes up to C₁₀ are constructed. Comparisons between experimental data and simulations show good agreement, demonstrating the robustness of the monomethyl and dimethyl iso-alkanes chemical mechanisms and the effectiveness of the proposed reaction rate rules.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114340"},"PeriodicalIF":5.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Confinement effects on a supersonic hydrogen jet flame in a duct","authors":"L. Gaipl ,&nbsp;T. Poinsot","doi":"10.1016/j.combustflame.2025.114302","DOIUrl":"10.1016/j.combustflame.2025.114302","url":null,"abstract":"<div><div>This study investigates high-speed, confined hydrogen-air jet flames, representative of leak scenarios from a high pressure hydrogen tank in practical applications. Using high-fidelity Large Eddy Simulation (LES) with detailed combustion chemistry and heat transfer modeling, the research examines a round supersonic jet flame confined within a duct, subjected to an air crossflow and impinging on the duct walls. The confined hydrogen jet flame interacts strongly with its surroundings (Viskanta, 1993), leading to significant thermal stresses and accelerated wall degradation. Two configurations are compared: Case W, where the flame has sufficient space to ignite and develop before interacting with the opposite wall (Bradley et al., 2019), and Case N, where the nozzle-to-plate spacing is smaller than the flame lift-off height, resulting in partial flame quenching due to confinement. Substantial differences are observed between cases W and N. For Case W, the flame is attached to the jet, exhibits a central premixed core followed by a stabilized diffusion zone like in free jet flames. For Case N, this jet region is quenched. However, the overall flame does not extinguish and combustion proceeds in a large diffusion flame, stabilized away from the jet. While higher quantities of unburnt hydrogen exit the duct compared to Case W, Case N exhibits similar heat loads onto the tunnel walls. This behavior is attributed to the changed flame stabilization as well as confinement effects on the crossflow jet interaction, that impact heat transfer characteristics. Last, an analysis of the probability density functions of temporally averaged local wall heat fluxes indicates a spatially more evenly distributed heat transfer for Case N than for Case W.</div><div><strong>Novelty and significance statement</strong></div><div>Supersonic hydrogen jet flames (issuing from a high-pressure tank through a nozzle) are usually studied in free space. Recent safety concerns for hydrogen leaks require to study how hydrogen jets will behave in very confined setups, where the nozzle exit to plate spacing is smaller than the nominal lift-off height of the jet flame. The investigation of these hydrogen jets into small ducts is crucial for safety in future hydrogen applications. This work presents the first detailed simulation of cases where the supersonic hydrogen jet is strongly confined in a duct. It shows that, for very small nozzle to plate spacings, hydrogen does not burn in the shear layer of the jet but diffuses and burns far away from the jet core, creating a new flame topology and different wall heat loads compared to standard free flames and classical impinging jets.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114302"},"PeriodicalIF":5.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman-Rayleigh and LIF-OH measurements in turbulent H2/N2 flames with and without compositional inhomogeneity","authors":"A.R.W. Macfarlane ,&nbsp;H. Tang ,&nbsp;M.J. Dunn ,&nbsp;G. Magnotti ,&nbsp;A.R. Masri","doi":"10.1016/j.combustflame.2025.114338","DOIUrl":"10.1016/j.combustflame.2025.114338","url":null,"abstract":"<div><div>This paper presents temperature and species measurements performed using Raman/Rayleigh scattering in turbulent partially premixed flames of H₂/N₂ = 40/60 by volume, issuing from the Sydney inhomogeneous piloted jet burner. Results are reported for three flames, with an equivalence ratio of φ = 4.76, one with a compositional inhomogeneous inlet, at 80 % of the blow-off velocity and the other two flames being compositionally homogeneous, one velocity is equal to the inhomgoeneous flame and the other at 80 % from blow-off. A key finding of this work is that the inhomogeneous flame is approximately half the length of the homogeneous flames, as verified using chemiluminescence and OH planar fluorescence imaging. Measurements of temperature and mass fractions of O₂, N₂, H₂O and H₂ reveal significant differences in the mixing, reactivity and differential diffusion between the three flames, particularly near the outlet. For the compositionally inhomogeneous case, there is a significant amount of unreacted and partially reacted fuel, at the outlet, and this is due to the short recess distance and large velocity ratio between the air in the annulus and fuel in the jet. These inhomogeneous mixtures, which may be stratified, interact with the hot pilot products and exhibit significant strain rates and hence local extinction. For both homogeneous cases, the flame burns robustly near the jet exit with only a modest increase in local extinction at higher jet velocities. The low velocity homogeneous flame has significant differntial diffusion close to the outlet, resembling a low strained multicomponent flamelet. Whilst both the inhomogeneous and high-velocity homogeneous flames have minimal differential diffusion, closely resemblimg a highly strained mutlicomponent and unity Lewis number flamelet simulation respectively. For all three flames, the mixture fraction, temperature, and species profiles approach similar scalar profiles downstream, reflecting a decay in the local extinction and differential diffusion effects.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114338"},"PeriodicalIF":5.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel approach for modeling iron microparticle oxidation during the reactive cooling process","authors":"Daoguan Ning ,&nbsp;Arne Scholtissek ,&nbsp;Andreas Dreizler","doi":"10.1016/j.combustflame.2025.114313","DOIUrl":"10.1016/j.combustflame.2025.114313","url":null,"abstract":"<div><div>This work introduces an easy-to-implement yet accurate method to model the temperature evolution of isolated iron microparticles during reactive cooling. The model is validated using state-of-the-art experimental data under multiple conditions. Because of its simplicity, this approach is poised for widespread adoption in large-scale iron dust flame modeling.</div><div><strong>Novelty and significance statement</strong></div><div>A novel approach is developed to model the reactive cooling of an isolated iron microparticle, which is validated using the experimental time history of particle temperature under different conditions. This method is more intuitive, accessible, and easier to implement compared to existing techniques. It significantly simplifies the modeling of iron particle combustion, enabling more efficient numerical simulations of iron dust flames.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114313"},"PeriodicalIF":5.8,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144572479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of Nitrogen Sites in Inhibiting the Growth of Nitrogen-containing Polycyclic Aromatic Compounds: A Theoretical Study and Soot Dynamic Model Improvement","authors":"Qingyang Liu,&nbsp;Haoye Liu,&nbsp;Tianyou Wang","doi":"10.1016/j.combustflame.2025.114334","DOIUrl":"10.1016/j.combustflame.2025.114334","url":null,"abstract":"<div><div>Although nitrogen-containing species are abundant intermediates in ammonia-doped hydrocarbon flame, the inhibitory effects of nitrogen-containing species on the formation of polycyclic aromatic hydrocarbons (PAHs) and soot have not been fully revealed yet. In this work, the reaction pathways for the formation of nitrogen-containing polycyclic aromatic compounds (NPACs) from methylenimine (CH₂NH) with benzene, naphthalene, and biphenyl were constructed to reveal the inhibitory effect of nitrogen sites introduced by nitrogen-containing species on the growth pathways of PAHs and soot. The G3(MP2,CC)//B3LYP method were employed to calculate the electronic structures and potential energy surfaces (PES). The Rice-Ramsperger-Kassel-Marcus (RRKM) theory and transition state theory methods were employed to calculate rate constants. PES analysis revealed that the reactions at the nitrogen site exhibit higher energy barriers compared to those at the carbon site. Rate constants analysis further indicated that the substitution and cyclization processes of the nitrogen sites of NPACs usually have a reaction rate constant of 1-2 orders of magnitude lower than that on the carbon sites, that is, the nitrogen sites exhibit significantly low reactivity during the growth process of NPACs. As a unique site in NPACs, the low-reactivity nitrogen site hinders the bonding of hydrocarbon molecules at this site, thereby inhibiting the growth of NPACs. Based on the above conclusions, a new soot dynamic model incorporating nitrogen chemistry was proposed. In this model, nitrogen-containing species present in high concentrations (NH_3<!-->, HCN, and CH₂​NH) generate nitrogen-containing functional groups with low-reactivity nitrogen sites on the soot surface through direct chemical reactions. Simulation results show that the new soot model significantly improves the prediction accuracy of soot reduction, with errors reduced by up to 80%. The predicted nitrogen-containing functional groups and nitrogen content of soot are also within the reasonable range supported by experimental data. This underscores the importance of accounting for the direct chemical effects of nitrogen-containing species in the soot model, and the low reactivity of nitrogen sites observed in this study serves as a theoretical foundation for inserting the inhibitory mechanism of nitrogen-containing functional groups on soot growth in the soot dynamic model.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114334"},"PeriodicalIF":5.8,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144569952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unsupervised neural-implicit laser absorption tomography for quantitative imaging of unsteady flames","authors":"Joseph P. Molnar ,&nbsp;Jiangnan Xia ,&nbsp;Rui Zhang ,&nbsp;Samuel J. Grauer ,&nbsp;Chang Liu","doi":"10.1016/j.combustflame.2025.114298","DOIUrl":"10.1016/j.combustflame.2025.114298","url":null,"abstract":"<div><div>This paper presents a novel neural-implicit approach to laser absorption tomography (LAT) with an experimental demonstration. A coordinate neural network is used to represent thermochemical state variables as continuous functions of space and time. Unlike most existing neural methods for LAT, which rely on prior simulations and supervised training, our approach is based solely on LAT measurements, utilizing a differentiable observation operator with line parameters provided in a standard spectroscopy database format. Although reconstructing scalar fields from multi-beam absorbance data is an inherently ill-posed, nonlinear inverse problem, our continuous space–time parameterization supports physics-inspired regularization strategies and enables data assimilation. Synthetic and experimental tests are conducted to validate the method, demonstrating robust performance and reproducibility. We show that our neural-implicit approach to LAT can capture the dominant spatial modes of unsteady flames from very sparse measurement data, indicating its potential to reveal combustion instabilities in measurement domains with minimal optical access.</div><div><strong>Novelty and Significance Statement</strong></div><div>Industrial environments, such as gas turbine test beds, present significant diagnostic challenges due to harsh operating conditions and limited optical access. In this work, we demonstrate the first long-time-horizon reconstructions of simultaneous 2D temperature and water vapor mole fraction fields in laboratory burners using neural-implicit laser absorption tomography (NILAT). We characterize NILAT’s performance through a synthetic phantom study featuring a realistic mean profile, broadband fluctuations, and tonal dynamics, highlighting its robustness and reconstruction accuracy. We also validate the applicability of established regularization parameter selection methods. This sensing framework extends beyond controlled laboratory conditions and offers potential for deployment in extreme environments where direct measurements are impractical.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114298"},"PeriodicalIF":5.8,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144569953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of applied AC electric field on flame spread over electrical wire with cross-linked polyethylene insulation","authors":"Zhisheng Li ,&nbsp;Huido Lee ,&nbsp;Jeong Park ,&nbsp;Suk Ho Chung","doi":"10.1016/j.combustflame.2025.114323","DOIUrl":"10.1016/j.combustflame.2025.114323","url":null,"abstract":"<div><div>The effect of applied AC electric field on flame spread over electrical wires with NiCr-core insulated by cross-linked polyethylene (XLPE) is experimentally investigated by varying the AC voltage and frequency. Results are compared with those for low-density polyethylene (LDPE) insulation, commonly studied in fire safety research. For the baseline case without applying electric field, XLPE-insulated case exhibits distinct behaviors such as flame splitting and a unique molten dripping via merging of newly-formed globular molten XLPE, which were not observed in LDPE-insulated one. Under applied electric fields, the flame spread rate (FSR) and molten insulation dynamics differ markedly between XLPE and LDPE. Two regimes of FSR behavior are identified for XLPE and three for LDPE, depending on voltage and frequency. At high voltage and frequency, induced magnetic fields promote flame vortex formation, increasing flame width and FSR, while excessive conditions lead to flame extinction through mass loss via electrospray and dielectrophoresis. Scaling analyses are applied to elucidate the underlying mechanisms. The flame spread rates are phenomenologically characterized depending on these various phenomena in terms of the frequency and voltage, especially emphasizing the electric field intensity on the unburned wire surface. The extinction conditions are correlated with AC voltage and frequency.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114323"},"PeriodicalIF":5.8,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of NH3 addition on soot particles and gaseous precursors formation in C2H4 pyrolysis","authors":"Kai Zhang ,&nbsp;Yishu Xu ,&nbsp;Ronghao Yu ,&nbsp;Jiahui Wu ,&nbsp;Xiaobei Cheng","doi":"10.1016/j.combustflame.2025.114324","DOIUrl":"10.1016/j.combustflame.2025.114324","url":null,"abstract":"<div><div>The pyrolysis of C₂H₄/NH₃ mixtures was conducted in a plug flow reactor (PFR) in the temperature range of 973 K-1373 K. The pyrolysis products, including C₂H₄, NH₃, C₂H₂, C₆H₆ and HCN, were quantified using gas chromatography (GC) and Fourier transform infrared (FTIR) spectroscopy to elucidate the thermal decomposition behavior of C₂H₄ and NH₃, as well as the effects of NH₃ on the formation of gaseous soot precursors. The results indicate that both C₂H₄ and NH₃ conversion increase during co-pyrolysis compared to their individual pyrolysis. Moreover, C₂H₄ shows a more pronounced promoting effect on NH₃ decomposition. Kinetic analysis reveals that the reactions C₂H₄ + NH₂ and NH₃ + CH₃ are primarily responsible for the increased conversion of C₂H₄ and NH₃, respectively. The effects of NH₃ on soot precursors formation (e.g., C₂H₂ and C₆H₆) exhibit a non-monotonic trend with reaction temperature. Specifically, NH₃ addition promotes soot precursors formation below 1273 K but inhibits it above 1273 K. This trend is determined by the competition between NH₃-induced enhancement of C₂H₄ decomposition and the effects of C<img>N interactions. The former consistently promotes the formation of soot precursors, while the latter becomes significantly effective in inhibiting their formation only above 1273 K by removing C atoms from participating in soot precursors formation. This finding is supported by FTIR measurements with a significant increase of HCN being formed at temperature at 1273 K. It should be noted that as the temperature further increases, the concentration of HCN decreases due to its involvement in the formation of N-containing polycyclic aromatic hydrocarbons (NPAHs). Meaningfully, the molecular structure of NPAHs were identified using gas chromatography-mass spectrometry (GC–MS). Notably, existing kinetic mechanisms are unable to satisfactorily predict the quantitative trends of the experimental results, highlighting the need for further mechanism improvement and refinement.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114324"},"PeriodicalIF":5.8,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144562940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}