Combustion and Flame最新文献

{"title":"N2O reduction with selective excitation of species by non-equilibrium plasma in an NH3/air mixture","authors":"Nan Liu ,&nbsp;Qi Chen ,&nbsp;Xingyu Lu ,&nbsp;Jiaying Pan ,&nbsp;Haiqiao Wei ,&nbsp;Xingqian Mao","doi":"10.1016/j.combustflame.2025.114164","DOIUrl":"10.1016/j.combustflame.2025.114164","url":null,"abstract":"<div><div>Non-equilibrium plasma can enhance NH₃ combustion and simultaneously decrease N₂O/NO_x emissions at low temperatures. This study proposes a method of selective excitation of specific species in an NH₃/air mixture, such as O₂, N₂, air, or NH₃, to assess the effects for decreasing N₂O concentrations in the non-equilibrium plasma-assisted NH₃ oxidation via numerical modeling. The selective excitation is realized by removing the electron impact reactions and chemical reactions involving excited species apart from the target species. The results demonstrate that the selective excitation of specific species can significantly reduce N₂O concentrations compared with plasma-excited NH₃/air mixtures at low temperatures. Specifically, the optimal N₂O emission reduction at 800 K is achieved with plasma excitation of O₂. Due to the absence of interactions between NH₃ and electron/electronically excited state species N₂* and N(²D), the concentrations of NH/NH₂ radicals contributing to N₂O production dramatically decrease. Meanwhile, the primary N₂O consumption pathway becomes more prominent due to the efficient production of O(¹D). The reaction rate of the main N₂O production pathway is 1–2 orders of magnitude lower than that of the NH₃/air mixture. This work offers valuable insight and guidance for combustor design in advanced engines to effectively reduce N₂O emissions by using non-equilibrium plasma.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114164"},"PeriodicalIF":5.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792533","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":"Experiments and simulations of aluminum particle agglomeration based on the real structure of propellants","authors":"Hui Liu ,&nbsp;Guangxue Zhang ,&nbsp;Huanhuan Gao ,&nbsp;Wenke Zhang ,&nbsp;Jianzhong Liu","doi":"10.1016/j.combustflame.2025.114146","DOIUrl":"10.1016/j.combustflame.2025.114146","url":null,"abstract":"<div><div>In the combustion procession of solid propellants, aluminum particles tend to coalesce and eventually produce spherical agglomerates with diameters ranging from tens to hundreds of micrometers on the burning surface. This study proposed the characterization of the agglomeration process and accurate prediction of the agglomerate size of aluminum particles in solid propellants through the combined application of experimental and modeling techniques. The true structures of three solid propellants were obtained using 3D X-ray imaging technology, based on which the three-dimensional topological structure of the solid propellant was established. Considering physical processes such as the regression of the burning surface of the solid propellant, aluminum particle exposure, turbulent pulsation, and the heating and melting of aluminum particles, the agglomeration process, the size distribution of aluminum agglomerates were eventually obtained through simulation. The agglomeration process and the size distribution of aluminum agglomerates during the combustion of three solid propellants at 7 MPa were obtained using an electric heating wire ignition combustion experimental system combined with a high-speed camera. In this study, the re-agglomeration process of agglomerates occurring after detachment from the burning surface (both near and far from the burning surface) was captured using experimental methods for the first time. The simulation results were compared with the experimental results, validating the accuracy of the model from three aspects: the movement process of the burning surface and the agglomerate structure, special agglomeration behavior (re-agglomeration at different distances from the burning surface), and the size distribution of agglomerates. The deviation in the equivalent mean particle size (<em>D</em>₅₀, <em>D</em>₉₀, and <em>D</em>_4,3) of the aluminum agglomerate size distribution between the experimental results and the simulation results were all &lt;8.60 %. This indicates that the model established in this study can accurately predict the size distribution of aluminum agglomerates. Further predictions were made using this model to study the effects of changes in pressure (3–10 MPa), aluminum particle volume content (8 %-14 %), and ammonium perchlorate (AP) particle size (46–456 µm) on aluminum particle agglomeration. The results showed that increasing the pressure reduces the degree of aluminum particle agglomeration, while increasing the aluminum content or AP particle size exacerbates aluminum particle agglomeration.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114146"},"PeriodicalIF":5.8,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768574","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":"Combustion kinetics of the e-fuels methyl formate and dimethyl carbonate: A modeling and experimental study","authors":"Jianfei Yang ,&nbsp;Sascha Jacobs ,&nbsp;Chaimae Bariki ,&nbsp;Joachim Beeckmann ,&nbsp;Florian vom Lehn ,&nbsp;Dong Yan ,&nbsp;Karl Alexander Heufer ,&nbsp;Heinz Pitsch ,&nbsp;Liming Cai","doi":"10.1016/j.combustflame.2025.114112","DOIUrl":"10.1016/j.combustflame.2025.114112","url":null,"abstract":"<div><div>The Oxygenated hydrocarbons methyl formate (MeFo) and dimethyl carbonate (DMC) are regarded as promising e-fuel candidates. Their blends were investigated in engine experiments, showing satisfactory performance. In this work, the reaction kinetics of MeFo, DMC, and their blends are thus investigated for a deep understanding of their fundamental combustion characteristics. A chemical mechanism is proposed based on a newly developed MeFo model, which was revised by including missing reaction channels, incorporating rate and thermochemical data calculated theoretically at a high level, and modifying rate constants of sensitive reactions. In a comprehensive comparison of literature models with all available experimental data, the DMC mechanism of Sun et al. (Sun et al., 2016) shows the best performance, and its DMC-specific chemistry is thus added to the MeFo mechanism. The DMC submechanism is further revised in terms of reaction pathways and rate coefficients for improved prediction accuracy, where the rate coefficients of DMC reactions are updated analogously to the corresponding reactions in the MeFo submechanism if applicable, according to the similar C-H bond dissociation energies of DMC and MeFo. The mechanism is validated based on both experimental literature data for neat MeFo and DMC as well as new ignition delay times and laminar burning velocities measured as part of this study for their blends. Good agreement is observed between model predictions and experiments over a wide range of conditions. Finally, the underlying reaction pathways of neat MeFo and DMC as well as their blends are explored by means of reaction flux analysis, and implications are discussed in terms of their engine application potentials. It is revealed that the blending has a very minor impact on the underlying relative reaction fluxes of the two components.</div><div><strong>Novelty and Significance Statement</strong></div><div>The reaction kinetics of the promising e-fuel candidates MeFo, DMC, and their blends are investigated experimentally and numerically in this work. New experimental data of ignition delay times and laminar burning velocities are reported for the blends of MeFo and DMC, which are missing in the literature. A new kinetic model is proposed, which is validated successfully against all available literature data for neat MeFo and DMC as well as the new experimental results obtained as part of this study. The reaction pathways of MeFo, DMC, and their blends are explored. It is revealed that the blending has a very minor impact on the underlying relative reaction fluxes of the two components.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114112"},"PeriodicalIF":5.8,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768063","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":"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}