Combustion and Flame最新文献

{"title":"Interaction of ammonia with nitric oxide and nitrous oxide: Multi-species time-history measurements and comprehensive kinetic modeling","authors":"Jiabiao Zou ,&nbsp;Mohammad Adil ,&nbsp;Ali Elkhazraji ,&nbsp;Aamir Farooq","doi":"10.1016/j.combustflame.2025.114135","DOIUrl":"10.1016/j.combustflame.2025.114135","url":null,"abstract":"<div><div>Interaction chemistry of ammonia and nitrogen oxides (NOx and N₂O) was investigated with the help of laser-based multi-species measurements in a shock tube. Mid-infrared laser diagnostics were set up to measure the time-histories of NH₃, NO, N₂O and H₂O in shock-heated NH₃/NO/Ar and NH₃/N₂O/Ar mixtures over temperatures of 1418–2381 K and pressures of 1.10–1.90 bar. A comprehensive H/N/O nitrogenous combustion model was formulated and validated with our experimental data, as well as a wide array of literature data encompassing various NH₃-NOx systems and other nitrogenous systems over temperatures of 425–2455 K, pressures of 0.8–100 bar, and equivalence ratios of 0.23–2.7. In the NH₃-NO system, the reactions NH₂+NO=N₂+H₂O and NH₂+NO=NNH+OH dominate NH₃ consumption and NO reduction, while NH+NO=N₂O+<em>H</em> governs N₂O formation. Sensitivity analysis of the branching ratio of NH₂+NO→NNH+OH and NH₂+NO→N₂+H₂O highlighted the significance of the proposed rate values in improving model performance, particularly at temperatures below 1800 K. In the NH₃-N₂O system, the kinetics of NH₂+N₂O, NH+N₂O and NH₃/NH₂/NH+<em>O</em> were identified as critical targets for kinetic modeling. Experimental and kinetic analysis revealed a three-stage NO reduction phenomena in NH₃-NO system, with effective NO reduction occurring over a narrow temperature range of 1400–1600 K and residence times ranging 1 to 700 ms. In the NH₃-N₂O system, nearly 90 % nitrogen oxides reduction was observed over 1075–1600 K and residence times of &lt;1 s. These findings provide valuable insights for optimizing ammonia-fueled combustion systems to minimize nitrogen oxide emissions.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114135"},"PeriodicalIF":5.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746574","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":"Experimental study of butanol droplet combustion in a turbulent, elevated-pressure environment","authors":"Arash Arabkhalaj,&nbsp;Cameron Verwey,&nbsp;Madjid Birouk","doi":"10.1016/j.combustflame.2025.114150","DOIUrl":"10.1016/j.combustflame.2025.114150","url":null,"abstract":"<div><div>To assist in the search for clean liquid alternative fuels for future combustion engines, the combustion characteristics of butanol droplets were experimentally investigated. The experiments were conducted under varying flow turbulence intensity, <span><math><msup><mrow><mi>q</mi></mrow><mrow><mn>0.5</mn></mrow></msup></math></span>, (up to <span><math><mrow><mn>0.5</mn></mrow></math></span> m/s), pressure (up to 11 bar), and ambient compositions, including different levels of <span><math><msub><mi>O</mi><mn>2</mn></msub></math></span>, <span><math><mrow><mi>C</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, and <span><math><msub><mi>N</mi><mn>2</mn></msub></math></span>, at room temperature. A fan-stirred spherical chamber, equipped with four pairs of axial fans, was used to generate a controlled turbulent flow field with negligible mean velocity. A 500 µm butanol droplet was suspended on a single micro-fiber at the center of the chamber and ignited using a coil resistance wire. The combustion process, including the droplet time history and luminous flame structure, was recorded using two synchronized cameras. The findings revealed that increasing ambient pressure enhances the burning rate, <span><math><msub><mi>K</mi><mi>b</mi></msub></math></span>, while the effect of turbulence varies with pressure. At low pressure, turbulence has minimal impact, whereas at higher pressure, <span><math><msub><mi>K</mi><mi>b</mi></msub></math></span> increases with <span><math><msup><mrow><mi>q</mi></mrow><mrow><mn>0.5</mn></mrow></msup></math></span>, before declining due to temporary luminous extinction (TLE). Butanol exhibits a lower <span><math><msub><mi>K</mi><mi>b</mi></msub></math></span> than heptane; however, under high-pressure, high-turbulence conditions, their <span><math><msub><mi>K</mi><mi>b</mi></msub></math></span> values converge. Additionally, butanol droplet combustion is influenced by <span><math><msub><mi>O</mi><mn>2</mn></msub></math></span> and <span><math><mrow><mi>C</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span> concentrations. Oxygen improves <span><math><msub><mi>K</mi><mi>b</mi></msub></math></span> by delaying TLE, while <span><math><mrow><mi>C</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span> reduces <span><math><msub><mi>K</mi><mi>b</mi></msub></math></span> by lowering flame temperature and thermal conductivity of the ambient mixture.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114150"},"PeriodicalIF":5.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-temperature ignition of ammonia/methyl isopropyl ketone: A shock tube experiment and a kinetic model","authors":"Weihao Zeng ,&nbsp;Chun Zou ,&nbsp;Tianci Yan ,&nbsp;Qianjin Lin ,&nbsp;Lingfeng Dai ,&nbsp;Jiacheng Liu ,&nbsp;Yu Song","doi":"10.1016/j.combustflame.2025.114004","DOIUrl":"10.1016/j.combustflame.2025.114004","url":null,"abstract":"<div><div>The ignition delay times (IDTs) of NH₃/methyl isopropyl ketone (MIPK) mixtures with MIPK blending ratios of 5 %, 10 %, and 30 % were measured at pressures of 1.75 and 10 bar, temperatures ranging from 1100 to 2000 K, under stoichiometric condition. The IDTs were found to exhibit a sharp decrease at 5 % MIPK blending ratio and then reduced slowly with further MIPK addition. Increasing pressure could enhance the ignition-promoting effects of MIPK. A detailed MIPK-NH₃ model was constructed including the MIPK sub-model, the NH₃ sub-model, and the cross-reactions between C-containing species and N-containing species which consisted of the prompt NO formation reactions and reburn type reactions, the recombination and oxidation reactions of small amines, H-abstraction reactions, and disproportionation reactions. The predictions calculated by the MIPK-NH₃ model are in good agreement with the measured IDTs. The analysis showed that the cross-reactions evidently inhibit the ignition of NH₃/MIPK, which is mainly attributed to the disproportionation reactions; and the ignition-inhibiting effects decrease with the increasing pressure or MIPK blending ratio. The effects of the MIPK blending ratio and cross-reactions on the ignition of NH₃/MIPK were analyzed in detail. The oxidation pathways of NH₃/MIPK were also discussed.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114004"},"PeriodicalIF":5.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746579","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":"Study on the in-flame electron transport behaviors towards early-stage engine knocking detection","authors":"Guangyu Dong ,&nbsp;Yanxiong Zhou ,&nbsp;Zhijun Wu ,&nbsp;Robert Dibble ,&nbsp;Liguang Li ,&nbsp;Ze Wang","doi":"10.1016/j.combustflame.2025.114140","DOIUrl":"10.1016/j.combustflame.2025.114140","url":null,"abstract":"<div><div>In future high-efficiency engines that implement high compression ratios, the occurrence of knock/super knock phenomena, primarily triggered by the end gas auto-ignition (EGAI), will pose a significant challenge. To address this issue, ion sensing technology has emerged as a highly promising approach for real-time detection of knock events. However, the reliability of ion sensing based EGAI detection is still poor due to the electron ambipolar diffusion process. When EGAI occurs at the far end of the engine combustion chamber, the electrons produced in the EGAI zone are bound to positive ions due to electrostatic force. In such case, the electrons can hardly diffuse out of the zone and be collected by the anode of spark plugs (which functioned as the ion probes in production engines), consequently leading to the fault of ion sensing method. To overcome this challenge, the behaviors of electron transport under various external electric field configurations are analyzed by simulating the end gas ignition process in a constant volume combustion chamber (CVCC). The findings demonstrate that an external electric field can surmount the electrostatic force acting on electrons and positive ions. Specifically, when the voltage applied from the DC power source in the ion sensing circuit exceeds 10 kV, numerical analysis suggests a transition from electron ambipolar diffusion to unipolar diffusion. Consequently, electrons can successfully diffuse out of the EGAI zone in the CVCC. This enables the collection of ion current signals by an ion probe positioned outside of that zone. Thus, the potential of early-stage engine knocking detection based on ion sensing is highlighted, particularly since high voltages can be configured by incorporating engine ignition modules into the ion sensing systems.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114140"},"PeriodicalIF":5.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746577","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":"Examination of differential diffusion effects in spatially-developing supersonic mixing layer hydrogen flames","authors":"Jieli Wei ,&nbsp;Xu Zhu ,&nbsp;Nana Wang","doi":"10.1016/j.combustflame.2025.114138","DOIUrl":"10.1016/j.combustflame.2025.114138","url":null,"abstract":"<div><div>Differential diffusion (DD) plays a crucial role in the fundamental understanding of combustion process, particular in the context of hydrogen or hydrogen-blended fuel flames. This paper intends to address whether the impact of DD on the flame stabilization in the turbulence-dominant supersonic flow can be negligible and if not, to elucidate its mechanisms. To this end, a spatially-developing supersonic non-premixed mixing layer hydrogen flame is simulated by large eddy simulations. Three distinct flow-chemistry interaction patterns: <em>laminar flow-chemistry, transition-chemistry</em>, and <em>turbulence-chemistry</em> are well designed within the mixing layer to examine the dependence of the DD effect on turbulence and its implications for flame stabilization. Results show that the importance of DD in flame-base zones of <em>transition-chemistry</em> and <em>turbulence-chemistry</em> interaction patterns is more pronounced than in <em>laminar flow-chemistry</em> one, even though their turbulence effects are more significant. The DD effect is observed to shorten the flame lift-off length and shift the leading point dynamic from a low-frequency to a high-frequency mode. Further “budget analysis” of transport- and chemistry- effect of DD shows that although the transport contribution of DD diminishes in turbulence-dominant flow-chemistry interaction patterns, the chemistry contribution of DD, i.e., sensitivity of the ignition delay time (IDT) to DD, is increased due to the low mixture temperature. Specifically, even a minor increase in the concentration of certain radicals, such as H, caused by DD can result in a significant reduction in IDT. This is primarily responsible for DD shortening the flame lift-off length within <em>transition-chemistry</em> and <em>turbulence-chemistry</em> interaction patterns. In <em>laminar flow-chemistry</em> pattern, DD facilitates the reaction to withstand high strain rates and in turn reducing the flame lift-off length.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114138"},"PeriodicalIF":5.8,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143739690","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":"Theoretical study of the real-fluid laminar flame propagation under supercritical conditions by using the virial equation of state and the Enskog transport model","authors":"Junfeng Bai,&nbsp;Xin Zhang,&nbsp;Hao Zhao","doi":"10.1016/j.combustflame.2025.114144","DOIUrl":"10.1016/j.combustflame.2025.114144","url":null,"abstract":"<div><div>A real-fluid computation model using the Virial equation of state and the Enskog transport model was developed in this work to simulate real-fluid laminar flame propagations, and it was also compared with the Redlich-Kwong-Ely-Hanley/Takahashi real-fluid model in literature. The real-fluid effects of equation of state, thermodynamics, chemical potential, thermal conductivity, and mass diffusion have been investigated on the freely propagating flame simulations of different fuels. The contribution and the source of uncertainties by different real-fluid properties are also comprehensively discussed. The overall effects of real-fluid behaviors on the laminar flame speed simulations in H₂O-dilute mixtures can reach 35 % at 100 atm, which reveal that accurate descriptions of real-fluid effects are crucial for flame speed predictions, especially using dilute gas with a high polarization, such as H₂O. The Redlich-Kwong-Ely-Hanley/Takahashi model shows severe over-predictions of the hydrogen laminar flame speeds due to its significant weakness in predictions of thermal conductivities of mixtures by comparing with the NIST data, while the present Virial-Enskog model exhibits more reasonable predictability. The real-fluid simulations of the laminar flame speeds of DME and n-heptane flames by using the Virial-Enskog model and the Redlich-Kwong-Ely-Hanley/Takahashi model are compared with the available experimental data. It shows a crucial real-fluid effect on the simulations of DME and n-heptane flame speeds, up to 8 % discrepancy from the ideal-gas flame speed prediction, even at 20–25 atm. Overall, the Virial-Enskog model provides better estimations of the real-fluid behaviors than the empirical Redlich-Kwong-Ely-Hanley/Takahashi model, especially at high pressures.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114144"},"PeriodicalIF":5.8,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746576","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":"Experimental and modeling study on the high-temperature ignition of ammonia/diethyl ketone","authors":"Tianci Yan,&nbsp;Chun Zou,&nbsp;Qianjin Lin,&nbsp;Yi Yuan,&nbsp;Lingfeng Dai,&nbsp;Jiacheng Liu","doi":"10.1016/j.combustflame.2025.114069","DOIUrl":"10.1016/j.combustflame.2025.114069","url":null,"abstract":"<div><div>The ignition delay times (IDTs) of NH₃/diethyl ketone (DEK) mixtures at DEK blending ratios (<em>X</em>_DEK) of 0.05, 0.1, and 0.5 were measured in a shock tube at equivalence ratios (φ) of 0.5, 1.0 and 2.0, pressures of 1.75 and 10 bar, and temperatures from 1200 to 1900 K. The addition of DEK with <em>X</em>_DEK = 0.05 significantly improves the combustion performance of ammonia. A detailed DEK-NH₃ model was proposed including the NH₃ sub-model, the DEK sub-model, and the cross-reactions between hydrocarbon/oxygenated species and nitrogen-containing species. The model well predicts the IDTs of NH₃/DEK mixtures measured in this study, and the IDTs of pure NH₃ reported in the literature. The cross-reactions consist of the prompt NO and reburn reactions (reaction-class 1), the recombination reactions and the oxidation reactions of small amines (reaction-class 2), the H-atom abstraction reactions (reaction-class 3), and the disproportionation reactions (reaction-class 4). The comparison of the model predictions shows that the reaction-class 1 and 2 have negligible effects on the ignition. The reaction-class 3 slightly promotes the ignition and the reaction-class 4 significantly inhibits the ignition. The dependence of the effects of the cross-reactions on the blending ratio and pressure are discussed in detail. The NH₃/DEK oxidation pathway is also analyzed.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114069"},"PeriodicalIF":5.8,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746578","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":"Fundamental investigation of methanol flash boiling combustion under direct injection conditions","authors":"Mingli Cui ,&nbsp;Mohamed Nour ,&nbsp;Jinhong Fu ,&nbsp;Weixuan Zhang ,&nbsp;Guodong Wang ,&nbsp;Hongchang Xu ,&nbsp;Bowei Yao ,&nbsp;Xuesong Li","doi":"10.1016/j.combustflame.2025.114147","DOIUrl":"10.1016/j.combustflame.2025.114147","url":null,"abstract":"<div><div>The task of reducing carbon emissions has become a primary goal for energy utilization purposes via combustion. The use of e-fuels/alternative fuels is a viable solution to enable zero carbon emission during the life cycle. However, the combustion of such fuels, such as methanol, is somehow different from combusting gasoline or diesel in the aspects of fuel atomization/evaporation and combustion mechanisms, etc. Flash boiling atomization is a promising atomization approach for improving the atomization and evaporation of alcohol fuels. The use of flash boiling atomization has been validated in optical gasoline direct injection (GDI) engines. However, the fundamental understanding of the impact of flash boiling on fuel combustion is still missing. This investigation focuses on the combustion of methanol fuel in a constant volume combustion chamber in a GDI fuel-air mixing fashion. The spray and flame propagation characteristics are obtained via high-speed imaging. Furthermore, detailed combustion product analysis is carried out using an online Fourier transform infrared (FTIR) device to distinguish the fundamental difference when combusting the fuel under sub-cooled and flash boiling conditions. Soot produced during the combustion is collected by mesh grids and analyzed via a transmission electron microscope (TEM). The results show that flash boiling promotes combustion efficiency under rich combustion conditions. Compared to sub-cooled combustion, methanol flash boiling combustion increases CO/CO2 emissions by 11.8 % and aldehydes emissions by 19.3 %, while reducing unburned hydrocarbons by approximately 30 %. NOx and aromatics emissions are decreased under methanol flash boiling combustion by 49.7 % and 55.1 %, respectively. Compared to n-heptane, methanol sub-cooled combustion reduces the production of soot particles. The stronger oxidation effect of methanol suppresses nuclei-mode soot generation, and the soot particles from methanol combustion feature shorter, more compact, and orderly stacked graphene layers. Moreover, flash boiling atomization further inhibits soot formation from methanol combustion.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114147"},"PeriodicalIF":5.8,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143740084","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 general formalism for determining the unburnt composition in multi-stream species transport-based CFD simulations","authors":"Simone Castellani ,&nbsp;Gianmarco Lemmi ,&nbsp;Pier Carlo Nassini ,&nbsp;Roberto Meloni ,&nbsp;Antonio Andreini","doi":"10.1016/j.combustflame.2025.114128","DOIUrl":"10.1016/j.combustflame.2025.114128","url":null,"abstract":"<div><div>The imperative to decarbonise combustion necessitates technical solutions that increasingly rely on the concurrent utilisation of different fuels and/or oxidisers. The complexity of the reactive mixture compositions in such scenarios poses additional challenges from a CFD modelling perspective. While species transport models can generally describe multi-stream combustion problems directly, the definition of turbulence-chemistry interaction closures or the proper comprehension of combustion regimes often requires the reconstruction of the non-reactive mixing field. This work proposes a general comprehensive formalism for determining the unburnt composition in multi-stream combustion environments. The method relies on the elemental mass fraction conservation for the definition of a linear system that can be solved at runtime to retrieve the local unburnt mixture composition. The introduced formalism allows to assess the number of auxiliary stream-tracking scalars <span><math><mrow><mi>a</mi><mo>−</mo><mi>p</mi><mi>r</mi><mi>i</mi><mi>o</mi><mi>r</mi><mi>i</mi></mrow></math></span>, thereby minimising computational efforts and effectively enabling the use of the inherent information within the set of transported species. The study presents an application example where a dual-fuel turbulent combustion scenario is numerically investigated. In this context, the consistency of the method with respect to the use of passive scalars has been discussed with and without the species equi-diffusivity assumption. A procedure for the <span><math><mrow><mi>a</mi><mo>−</mo><mi>p</mi><mi>r</mi><mi>i</mi><mi>o</mi><mi>r</mi><mi>i</mi></mrow></math></span> estimation of the error introduced by the species preferential diffusion has been proposed, providing insights about the expected uncertainty on the predicted mixture composition and the respective flame properties.</div><div><strong>Novelty and Significance Statement</strong></div><div>The determination of the non-reactive mixing field is crucial for understanding reactive CFD simulations based on species transport. Additionally, in turbulent combustion models, knowing the unburnt composition is often a pivotal requirement for the model closure. While recalculated mixture fractions can determine the unburnt composition in dual-stream problems, this approach is inappropriate for multi-stream problems. This research introduces a novel generalised method for determining unburnt mixture composition in multi-stream combustion scenarios using CFD calculations based on species transport. The proposed method minimises the need for additional passive scalars by efficiently utilising existing information from the solved equations and boundary conditions, leveraging elemental mass fraction conservation.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114128"},"PeriodicalIF":5.8,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725034","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":"N-containing pollutant formation in pyrrole counterflow diffusion flames","authors":"Bingjie Chen ,&nbsp;Sebastian Faller ,&nbsp;Luna Pratali Maffei ,&nbsp;Andrea Nobili ,&nbsp;Matteo Pelucchi ,&nbsp;Xingcai Lu ,&nbsp;Heinz Pitsch","doi":"10.1016/j.combustflame.2025.114136","DOIUrl":"10.1016/j.combustflame.2025.114136","url":null,"abstract":"<div><div>Biomass conversion through direct combustion (energy production) or pyrolysis (bio-oil production) are novel concepts to reduce CO₂ emission in the energy sector. However, the nitrogen content in biomass feedstocks may result in elevated N-containing pollutants, e.g., NO_x, NH₃, HCN, and nitriles, yet their formation chemistry remains unclear. In this work, we studied N-containing pollutant formation in counterflow diffusion flames fuelled by pyrrole, a biomass tar surrogate component that accounts for the majority of fuel nitrogen. 27 species, including 8 N-containing species, were identified and measured in three flames with designed boundary conditions to reveal the influence of flame temperature and methane addition. Species mole fraction comparisons showed that methane addition and higher flame temperature promoted C₂–C₆ hydrocarbon formation, but mole fractions of N-containing species did not change much, reflecting less dependence on flame temperature or hydrocarbons in the species pool. An existing kinetic model for pyrrole pyrolysis and combustion was developed by updating the formation reactions of N-containing species based on recent literature studies. Numerical simulations using the kinetic model well reproduced mole fractions of most species except for NO and NO₂. Model analyses illustrated the nitrogen conversion pathways from pyrrole to individual N-containing pollutant species, and indicated the possible reactions for underestimated mole fractions of NO and NO₂. This work contributes to a better understanding of the combustion properties of N-containing fuels and N-containing pollutants in the context of biomass energy clean utilization.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114136"},"PeriodicalIF":5.8,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}