Proceedings of the Combustion Institute最新文献

{"title":"Unveiling the pyrolysis mechanism of 2-Azido-N,N-dimethylethylamine via SVUV-PIMS and kinetic modeling","authors":"Qingbo Zhu,&nbsp;Weiping Pan,&nbsp;Qiang Xu,&nbsp;Long Zhu,&nbsp;Zhandong Wang","doi":"10.1016/j.proci.2026.106225","DOIUrl":"10.1016/j.proci.2026.106225","url":null,"abstract":"<div><div>2-Azido-N,N-dimethylethanamine (DMAZ) is a promising candidate for use as bipropellant that has been studied as the potential substitute for hydrazine. An in-depth understanding of the DMAZ decomposition mechanism is crucial for its application in engines. In this work, the pyrolysis of DMAZ was conducted in a jet-stirred reactor (JSR) at atmospheric pressure over a temperature range of 480–900 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was employed to detect numerous intermediates, including alkanes, alkenes, amines, imines, and nitriles. Experimental results indicate that DMAZ begins to decompose at temperatures as low as 540 K. The primary consumption pathway was identified as N<img>N bond cleavage of the azido group, generating N₂ and the N(CH₃)₂CH₂CHNH, which governs the pyrolysis behavior of DMAZ. Furthermore, a kinetic model was developed and validated, demonstrating good predictive capability for fuel reactivity and the formation of most intermediates. The detailed experimental results and kinetic analysis in this work are expected to contribute valuable references to further research on the combustion mechanism of DMAZ.</div></div><div><h3>Novelty and significance statement</h3><div>The pyrolysis of the hypergolic propellant 2-Azido-N,N-dimethylethylamine (DMAZ) was investigated using SVUV-PIMS to map the detailed species distribution. This approach revealed numerous nitrogen-containing intermediates, providing novel insights into the primary reaction pathways and the role of azido group dissociation. Based on these findings, a comprehensive thermal decomposition network was constructed. A validated kinetic model incorporating key unimolecular and H-abstraction pathways was developed, which captures the decomposition process and intermediate formation. This study provides fundamental insights into the thermal decomposition mechanism of DMAZ, a promising green hypergolic propellant candidate intended to replace toxic hydrazine-based fuels. By offering detailed speciation data and a validated kinetic model, the research delivers critical reference information for the development of DMAZ-based propulsion systems, and supports more accurate predictions of fuel behavior under engine-relevant conditions. These findings contribute to the advancement of safer and more sustainable propulsion technologies and support the global effort to transition toward environmentally friendly propellants.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106225"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148656886","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":"Carbon particle formation, nanostructure and morphology in H2-blended CH4 pyrolysis: Shock tube experiments and modeling","authors":"Gibson Clark,&nbsp;Chengze Li,&nbsp;Mohammad Adib,&nbsp;Jahanbakhsh Jahanzamin,&nbsp;Jesse W. Streicher,&nbsp;Enoch Dames,&nbsp;Shruthi Dasappa,&nbsp;Adam M. Boies,&nbsp;M. Reza Kholghy,&nbsp;Ronald K. Hanson","doi":"10.1016/j.proci.2026.106301","DOIUrl":"10.1016/j.proci.2026.106301","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In emerging electrified pyrolysis systems like those for hydrogen (H&lt;sub&gt;2&lt;/sub&gt;) and carbon nanoparticle (CNP) co-generation, H&lt;sub&gt;2&lt;/sub&gt; can significantly impact yields and CNP properties. H&lt;sub&gt;2&lt;/sub&gt; inhibits high-temperature particle synthesis via hydrogen-abstraction-carbon-addition (HACA) pathways, yet its influence on inception, morphology, and nanostructure remains unclear. This study examines the influence of 5% H&lt;sub&gt;2&lt;/sub&gt; addition to the pyrolysis of 5% methane (CH&lt;sub&gt;4&lt;/sub&gt;) in argon behind reflected shock waves at initial temperatures (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) of 1850–2450 K and pressures (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) around 4.6 atm. Time-resolved laser absorption quantified CH&lt;sub&gt;4&lt;/sub&gt; and acetylene (C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;) time histories, showing that H&lt;sub&gt;2&lt;/sub&gt; shifts more carbon into C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;, and constraining kinetic-model analysis of its influence on pathways to propargyl (C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;3&lt;/sub&gt;) and benzene (C&lt;sub&gt;6&lt;/sub&gt;H&lt;sub&gt;6&lt;/sub&gt;). A two-wavelength extinction scheme (633, 1064 nm) shows a &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; increase in induction time (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ind&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;), delayed maturity, and a &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; reduction in volume fraction (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;v&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) with H&lt;sub&gt;2&lt;/sub&gt; addition. Transmission electron microscopy (TEM) reveals primary particles with 22% smaller diameter (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;), yet similar spacing (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;0.4&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;nm&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) and length (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;0.85&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;nm&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) of the graphitic layers that formed between 2085–2355 K. Simulations can predict both &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;v&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; trends, but fail to capture &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ind&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; at high &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; at both temperature extremes. Combined experiments and modeling show the role of H&lt;sub&gt;2&lt;/sub&gt; in altering the pathways and partitioning of condensed-phase carbon that increase the prevalence of less ordered and optically weaker material, while delaying the formation and reducing the yields of typical CNP aggregate","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106301"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148737771","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":"Extending a two-equation acetylene/benzene based soot production model for pool fires fueled by heptane/toluene blends","authors":"Fatiha Nmira ,&nbsp;Hussain Najmi ,&nbsp;Jean-Louis Consalvi","doi":"10.1016/j.proci.2026.106001","DOIUrl":"10.1016/j.proci.2026.106001","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Two-equation, acetylene/benzene-based soot production models were applied with success to model soot production in buoyant flames fueled by aliphatics, such as ethylene or heptane. The objective of this article is to extend these models to predict soot production for liquid fuels containing aromatics, that are of great importance for fire safety applications. The extended model assumes that gas-phase chemistry governs the effects of fuel sooting propensity on soot formation rates (nucleation and surface growth) and that, for a given gas-phase thermochemical state, these effects scale inversely with the laminar smoke-point height, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;. In practice, the gas-phase related part of the soot formation rates for aliphatic/aromatic mixtures is scaled from those of a reference aliphatic fuel. Heptane is used as reference in the present study. The soot model was coupled with a steady laminar flamelet/presumed filtered density function approach, which properly models the interactions between chemistry, soot production, radiation, and turbulence. This was used to perform large eddy simulations of 15 and 30 cm diameter pool fires fueled by heptane and two heptane/toluene blends with toluene volume fractions of 5% and 10%, respectively. Model predictions reproduce with high fidelity the temperature and soot volume fraction statistics, as well as the radiative outputs. More specifically, for given pool diameter, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and height above the burner, the predicted soot volume fraction, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, satisfies the same normalized radial profile as the experiments, namely &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, supporting the modeling assumptions. The proposed methodology based on LSP concept can be readily extended to other alkane/aromatic surrogate fuels in fire safety applications. The principle challenge remains the extension of subgrid-scale turbulence-soot interaction model to predict the transition to heavily smoking flames.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Novelty and significance statement:&lt;/em&gt; This research addresses a fundamental issue for the fire community of soot production and radiation in sooting aliphatic/aromatic mixtures. This issue also concerns a broader audience than the fire community, as soot production by such mixtures is an important topic in engine combustion. The novel aspect of this research is to propose a methodology to extend two-equation acetylene/benzene-based soot production models that are widely used for fire and combustion applications, to model soot production in liquid fuels contain","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106001"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148314626","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 differential diffusion on the critical velocity gradient for boundary layer flashback of laminar hydrogen–air flames","authors":"Takuto Komatsu,&nbsp;Jianhong Lin,&nbsp;Evatt R. Hawkes","doi":"10.1016/j.proci.2026.106121","DOIUrl":"10.1016/j.proci.2026.106121","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Boundary layer flashback (BLF) has been a major challenge for hydrogen-fuelled lean premixed gas turbine combustors. Although the critical velocity gradient (CVG) model has been widely used to predict the onset of BLF, it does not incorporate the effects of differential diffusion, which for lean premixed hydrogen flames lead to local enrichment, potentially leading to higher flashback propensity than predicted by CVG. To investigate this, premixed hydrogen flames propagating in a laminar boundary layer adjacent to an isothermal wall are simulated using two-dimensional direct numerical simulation. To isolate and expose differential diffusion effects, numerical experiments are performed with different molecular transport models. Simulations are compared across equivalence ratios from 0.4 to 1.0 with (a) a mixture-averaged model with the Soret effect, (b) a mixture-averaged model without the Soret effect, and (c) a unity-Lewis-number model. Results show that the CVG concept effectively captures the trends for confined flashback limit for the unity-Lewis-number model, where differential diffusion is inherently suppressed. However, when differential diffusion is included, CVG significantly underpredicts the flashback limit in fuel-lean conditions, with the Soret effect enhancing the discrepancy. These effects are pronounced under very lean conditions but diminish with equivalence ratio. Strong local enrichment is observed in lean conditions, which we show leads to higher flame speeds, smaller penetration distance of the flame tip, and enhanced flow deceleration, all of which enhance flashback. Flow deceleration is qualitatively collapsed by a simple scaling model. Stretch is explored in pursuit of potential corrections to flame speed, however a large peak stretch and a wall heat transfer effect are observed, invalidating a linearised model. Although the CVG model is found to be fundamentally applicable, it must be modified to account for both differential diffusion and wall heat transfer to accurately predict the flashback limit for lean hydrogen combustion.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Novelty and significance statement:&lt;/em&gt; The development of large-scale, 100% hydrogen-fuelled, dry low emissions gas turbines would present new opportunities to decarbonise energy generation. To enable this, boundary layer flashback is a serious problem that must be mitigated. Through a novel comparison of two-dimensional direct numerical simulations with different molecular transport models, this paper presents the most comprehensive quantification to date of the importance of differential diffusion and the Soret effect in the context of critical velocity gradient model. It shows that both effects are significant, and that the widely used flashback criterion fails for lean hydrogen/air mixtures since it does not account for them. It therefore points to a need for revised models that include differential diffusion and offers insights that will be useful for their developme","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106121"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148656924","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":"Unraveling the decomposition of 1-phenylethyl hydroperoxide: Insights from synchrotron VUV mass spectrometry, theoretical calculations, and kinetic modeling","authors":"Shuyao Chen,&nbsp;Huicun Li,&nbsp;Zhihong Hu,&nbsp;Long Zhu,&nbsp;Lili Xing,&nbsp;Zhandong Wang","doi":"10.1016/j.proci.2026.106273","DOIUrl":"10.1016/j.proci.2026.106273","url":null,"abstract":"<div><div>The decomposition kinetics and reaction network of 1-phenylethyl hydroperoxide (1-PEHP), a key intermediate in the low-temperature oxidation of ethylbenzene, were investigated experimentally and theoretically. High-purity 1-PEHP was synthesized and its pyrolysis was studied in a jet-stirred reactor with toluene as OH radical scavenger. The pyrolysis experiments were conducted at 450–700 K and 1atm and the reaction products were analyzed by synchrotron vacuum-ultraviolet photoionization mass spectrometry (SVUV-PIMS). The decomposition rate constants of 1-PEHP were determined from the decay curve of 1-PEHP by assuming first-order kinetics. The measured rate constants agree well with the reported Arrhenius expression for organic hydroperoxides in the literature. The thermal decomposition and subsequent reaction pathways of the 1-phenylethyloxide radical were further explored using quantum chemical calculations. Based on these results, an optimized kinetic model was developed. The updated model reproduces well the experimental species profiles and provides improved predictions for benzaldehyde, acetophenone, ethylbenzene, styrene, and bibenzyl. Reaction pathway analysis reveals that 1-PEHP decomposition is dominated by O–OH bond dissociation, followed by benzaldehyde formation via β-scission of the C₆H₅CH(O<strong>·)</strong>CH₃ radical. The modified model enhances understanding of the low-temperature oxidation mechanism of short-chain aromatic hydrocarbons and provides valuable kinetic data for modeling low-temperature oxidation of ethylbenzene.</div><div>Novelty and significance statement: Despite its recognized role in ethylbenzene low-temperature oxidation, the decomposition kinetics of 1-phenylethyl hydroperoxide (1-PEHP) have not previously been determined on a species-specific basis, and current mechanisms rely on rate estimates derived from alkyl hydroperoxides. This study provides direct rate constants for 1-PEHP O–OH bond dissociation and establishes the decomposition pathways of the corresponding 1-phenylethyloxide radical using quantum chemical calculations. The resulting rate coefficients were incorporated into a refined kinetic model, leading to changes in reaction networks and improved agreement with experimentally observed aromatic product distributions. In particular, the analysis quantifies the dominance of benzaldehyde-forming channels and clarifies their coupling with benzyl radical chemistry. By replacing analogy-based parameters with experimentally and theoretically calculated values, this work reduces uncertainty in aromatic hydroperoxide chemistry and strengthens the mechanistic basis of low-temperature oxidation models for ethylbenzene and related fuels.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106273"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148657008","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":"Constructing CuCe/SAPO-34 with enhanced activity for ammonia combustion via rapid joule heating","authors":"Running Kang,&nbsp;Liwei Lu,&nbsp;Xiaokun Yi,&nbsp;Wenjun Liang,&nbsp;Feng Bin,&nbsp;Xiaolin Wei","doi":"10.1016/j.proci.2026.106208","DOIUrl":"10.1016/j.proci.2026.106208","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Catalytic NH&lt;sub&gt;3&lt;/sub&gt; combustion presents a promising strategy to overcome the challenges of high ignition temperature and excessive NO&lt;sub&gt;x&lt;/sub&gt; emissions in the clean utilization of carbon-free NH&lt;sub&gt;3&lt;/sub&gt; fuel. This investigation elucidated distinct structure-activity relationships and combustion pathways of CuCe/S catalysts prepared via different synthesis methods. The catalyst synthesized by rapid Joule heating (CuCe/S-J, T&lt;sub&gt;90&lt;/sub&gt;=330 °C) significantly outperforms its conventionally mixed counterpart (CuCe/S-M, T&lt;sub&gt;90&lt;/sub&gt;=396 °C) in NH&lt;sub&gt;3&lt;/sub&gt; combustion activity. Series of characterizations (&lt;em&gt;in situ&lt;/em&gt; ESEM and XAFS etc.) reveal that the superior activity of CuCe/S-J originates from its highly dispersed CuO dispersion (83.5%) on the SAPO support, and stronger Cu–Ce interaction induced by the rapid thermal process, which facilitates efficient electron transfer (Cu⁺+Ce&lt;sup&gt;4&lt;/sup&gt;⁺–O→Cu&lt;sup&gt;2&lt;/sup&gt;⁺+Ce&lt;sup&gt;3&lt;/sup&gt;⁺–O&lt;sub&gt;V&lt;/sub&gt;), generate more active Cu&lt;sup&gt;2&lt;/sup&gt;⁺ species (0.76) and Ce&lt;sup&gt;3&lt;/sup&gt;⁺–O&lt;sub&gt;V&lt;/sub&gt; sites at the interface. As evidenced by H&lt;sub&gt;2&lt;/sub&gt;-TPR and NH&lt;sub&gt;3&lt;/sub&gt;-TPD-MS, these features collectively enhance the redox ability and NH&lt;sub&gt;3&lt;/sub&gt; adsorption-activation. &lt;em&gt;In situ&lt;/em&gt; IR and isotopic (&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;2&lt;/sub&gt;) transient experiments delineate the reaction pathways: NH&lt;sub&gt;3&lt;/sub&gt; adsorbed on active sites (Cu-OH&lt;sup&gt;+&lt;/sup&gt; and Cu&lt;sup&gt;2+&lt;/sup&gt;) reacts with activated lattice oxygen to form key intermediates (HNO, NH&lt;sub&gt;4&lt;/sub&gt;⁺, NH&lt;sub&gt;2&lt;/sub&gt;), which subsequently decompose to produce N&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O at lower temperature on CuCe/S-J. These findings not only confirm the viability of environmentally friendly catalytic combustors for ammonia fuel, but provide fundamental insights for designing high-performance catalyst.&lt;/div&gt;&lt;div&gt;Novelty and significance statement: Catalytic combustion of high-concentration NH&lt;sub&gt;3&lt;/sub&gt; is a prospective technology to address the high ignition temperature and increased NO&lt;sub&gt;x&lt;/sub&gt; production in direct gaseous NH&lt;sub&gt;3&lt;/sub&gt; combustion, but is rarely reported so far. This work proposes an innovative rapid Joule heating method to prepare CuCe/-J catalyst, and the enhanced structure-activity relationship of CuCe/S-J is thoroughly elucidated. The activity of CuCe/S-J (T&lt;sub&gt;90&lt;/sub&gt;=330 °C) is better than CuCe/S-M (T&lt;sub&gt;90&lt;/sub&gt;=396 °C) by traditional Muffle furnace heating prepared method, attributed to the former exhibits stronger metal-metal and metal-support interactions, reflecting the higher Cu dispersity (83.5%) and more Cu&lt;sup&gt;2&lt;/sup&gt;⁺+Ce&lt;sup&gt;3&lt;/sup&gt;⁺–O&lt;sub&gt;V&lt;/sub&gt; interface on CuCe/S-J. The M-K reaction mechanism was precisely revealed by &lt;em&gt;in situ&lt;/em&gt; IR and isotopic (&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;2&lt;/sub&gt;) transient tracer. The significance of this research lies in demonstrating the feasibility of environmentally friendly catalytic combustors for ammonia fuel, while also advancing the understanding of advanced cat","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106208"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148582350","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":"Species-dependent NTC behavior during the evolution of wall-stabilized diethyl ether cool flames","authors":"Meng Zhou,&nbsp;Yuji Suzuki,&nbsp;Minhyeok Lee","doi":"10.1016/j.proci.2026.106240","DOIUrl":"10.1016/j.proci.2026.106240","url":null,"abstract":"<div><div>The increasing demand for high-efficiency and low-emission combustion strategies has stimulated sustained interest in understanding the low-temperature chemistry of alternative biofuels, such as diethyl ether (DEE). However, studies focusing on the low-temperature oxidation and ignition behavior of DEE cool flames remain limited. In this study, the negative temperature coefficient (NTC) behavior associated with the ignition process of a premixed wall-stabilized DEE/O₂ cool flame was investigated by examining the temporal evolutions of key intermediate species as the wall temperature increased. Experiments were conducted using a stagnation flow system at an equivalence ratio of 0.2. An aperture-sampling structure, a differential pumping system, and a high-resolution time-of-flight mass spectrometer (TOF-MS) enable time-resolved, minimally intrusive mass spectra acquisition. The results show that the low-temperature oxidation of DEE initiates near 600 K, followed by an NTC behavior beginning at approximately 680 K. Within the examined temperature range up to 740 K, the detected species behave distinctly, with ethyl vinyl ether (C₄H₈O) and 2-methyl-1,3-dioxolane (C₄H₈O₂-<em>cy</em>) showing monotonic increase, ethylene (C₂H₄) presenting a two-stage increase, while ethyl formate (C₃H₆O₂) and ethyl acetate (C₄H₈O₂) exhibit earlier turnover and subsequent decline. Among the kinetic models tested, the Tran et al. model qualitatively captures the observed evolution trends of most detected species, although it estimates a stronger overall low- and intermediate-temperature reactivity of DEE under the present conditions.</div></div><div><h3>Novelty and significance statement</h3><div>The low-temperature oxidation of DEE has been extensively examined in canonical configurations. However, studies of undiluted DEE cool flames remain limited. In particular, investigations incorporating coupled heat release and mass transfer are scarce, especially those addressing ignition and NTC behaviors that are essential for advancing combustion science and practical applications. This study addresses this gap by examining the species-resolved low-temperature oxidation processes of premixed DEE cool flames using time-resolved, minimally intrusive measurements of species evolution with a TOF-MS. This approach enables a detailed inspection of not only the initiation of low-temperature oxidation but also the subsequent NTC behavior in actual cool flame fields. The measured evolution patterns of individual species reveal important characteristics of DEE cool flame chemistry. They also provide benchmarks for validating and refining kinetic models under more complex and practical conditions beyond canonical reactors.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106240"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148582322","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":"RFNO-PINN: A Physics-Informed Neural Operator for Predicting Multi-Species Combustion Dynamics","authors":"Yang Zheng,&nbsp;Leilei Xu,&nbsp;Xieming Wu,&nbsp;Yuchen Zhou,&nbsp;Dezhi Zhou,&nbsp;Xingcai Lu,&nbsp;Xue-Song Bai","doi":"10.1016/j.proci.2026.106152","DOIUrl":"10.1016/j.proci.2026.106152","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Stiff chemical kinetics and multi-scale coupling pose significant challenges for deep learning surrogates of reacting flows, where purely data-driven models can violate conservation laws and produce thermochemically inconsistent states. This work proposes a physics-informed reaction-path-driven Fourier Neural Operator (RFNO-PINN) for efficient prediction of multi-dimensional multi-species reacting flows. The framework introduces reaction-path-driven species grouping to construct chemically meaningful operator branches and incorporates physics-informed losses to enforce thermochemical consistency and global conservation laws. Two classes of physics constraints are applied, including local thermochemical losses and global partial differential equation (PDE) residual losses. The proposed framework is evaluated on a laminar methane/air counterflow diffusion flame and a turbulent CH&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;/NH&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;/air dual-swirl flame. Compared with the baseline Fourier Neural Operator (FNO), the reaction-path-informed RFNO improves prediction accuracy, while RFNO-PINN further enhances physical consistency and suppresses nonphysical oscillations in species mass fractions. In long-horizon autoregressive rollouts, RFNO-PINN reduces the relative prediction error by 49% compared with FNO and significantly improves elemental mass conservation. Over the rollout window of 20 ms, the fluctuation range of the sum of elemental mass fractions decreases by 64% relative to RFNO and by 96% relative to FNO. These results show that by integrating reaction-path structure with physics-informed constraints, the proposed RFNO-PINN significantly improves the stability, accuracy, and physical consistency of neural operator surrogates for multi-species reacting flows.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Novelty and significance statement:&lt;/em&gt; This work presents a physics-informed neural operator framework (RFNO-PINN) that integrates combustion-specific structural priors with physics-based constraints for multi-species reacting flows. Building on existing physics-informed operator-learning studies that incorporate physics through training objectives, RFNO-PINN further embeds combustion-specific prior knowledge into the operator architecture through reaction-path-driven species grouping. The key innovations are threefold: (i) reaction-path-driven species grouping is introduced to construct chemically meaningful operator branches that capture coupled production–consumption relationships among species; (ii) an implicit residual correction (IRC) mechanism is developed to exploit temporal coherence from the input history and improve autoregressive prediction stability; and (iii) physics-informed constraints combining local thermochemical conservation and global PDE-residual regularization are incorporated, and their complementary roles in improving physical consistency an","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106152"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148582413","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 kinetic study on the role of NOx on the low-temperature oxidation of pentane isomers","authors":"Zhe Ren,&nbsp;Chao Zhou,&nbsp;Yaozong Duan,&nbsp;Zhen Huang,&nbsp;Dong Han","doi":"10.1016/j.proci.2026.106219","DOIUrl":"10.1016/j.proci.2026.106219","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Low-temperature oxidation of hydrocarbons in the presence of nitrogen oxides (NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt;) is of importance to advanced combustion systems because NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt; can alter ignition behavior, oxidation pathways, and pollutant formation through strong coupling with the radical pool. In ammonia/hydrocarbon dual-fuel concepts in particular, NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt; is not merely a final pollutant but also an active participant in the combustion chemistry, making it necessary to understand how NO and NO&lt;sub&gt;2&lt;/sub&gt; interact with representative hydrocarbon components. In this work, the effects of NO&lt;sub&gt;2&lt;/sub&gt; and NO on the oxidation of three pentane isomers, namely &lt;em&gt;neo&lt;/em&gt;-pentane, &lt;em&gt;n&lt;/em&gt;-pentane, and &lt;em&gt;iso&lt;/em&gt;-pentane, were investigated experimentally in a jet-stirred reactor (JSR) and interpreted using detailed kinetic models. Experiments were performed at an equivalence ratio of 1.0, atmospheric pressure, temperatures of 550–1050 K, and NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt; addition levels of 0, 0.05, and 0.1 mol%. The results show that both NO&lt;sub&gt;2&lt;/sub&gt; and NO inhibit low-temperature oxidation but promote fuel consumption at intermediate and high temperatures, while the magnitude and temperature dependence of the response strongly depend on fuel structure. Among these isomers, &lt;em&gt;n&lt;/em&gt;-pentane exhibits the strongest sensitivity, and 0.1% NO nearly eliminates its negative temperature coefficient (NTC) behavior. By contrast, &lt;em&gt;neo&lt;/em&gt;-pentane and &lt;em&gt;iso&lt;/em&gt;-pentane show weaker concentration effects and more uniform responses to NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt; addition. Kinetic analyses indicate that NO&lt;sub&gt;2&lt;/sub&gt; mainly acts through NO-NO&lt;sub&gt;2&lt;/sub&gt;-HONO/HNO&lt;sub&gt;2&lt;/sub&gt; cycling and radical-pool redistribution, whereas NO perturbs the low-temperature network more directly through ROO + NO = RO + NO&lt;sub&gt;2&lt;/sub&gt;, which competes with QOOH formation. These findings clarify the coupled roles of NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt; chemistry and molecular structure in pentane-isomer oxidation, and provide mechanistic insights relevant to NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt;-sensitization fuel oxidation in low-emission combustion systems.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Novelty and significance statement&lt;/h3&gt;&lt;div&gt;This work provides a systematic experimental and kinetic comparison of the effects of NO&lt;sub&gt;2&lt;/sub&gt; and NO on the low-temperature oxidation of three pentane isomers under unified JSR conditions. By combining oxidation measurements with updated kinetic models informed by recent mechanistic insight into NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt;-hydrocarbon cross-reactions, the study distinguishes the indirect radical-pool modulation induced by NO&lt;sub&gt;2&lt;/sub&gt; from the more direct ROO-consuming effect of NO. It further shows that the final oxidation response is governed by the intrinsic low-temperature chemistry of each fuel isomer. The resulting dataset and mechanistic interpretation provide useful benchmarks for developing NO&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt;-sensitive hydrocarbon oxid","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106219"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148582369","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":"Unraveling the positive ion chemistry in ammonia-methane flames","authors":"Andrey V. Cherepanov,&nbsp;Vitaly G. Kiselev,&nbsp;Anatoly A. Chernov,&nbsp;Andrey G. Shmakov,&nbsp;Denis A. Knyazkov","doi":"10.1016/j.proci.2026.106222","DOIUrl":"10.1016/j.proci.2026.106222","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Ammonia-methane mixtures are considered promising low-carbon fuels for future power generation, yet the understanding of ion chemistry in such flames remains limited. This work presents the first comprehensive study of positive ion chemistry in laminar premixed NH&lt;sub&gt;3&lt;/sub&gt;/CH&lt;sub&gt;4&lt;/sub&gt; flames at 1 atm by combining molecular beam mass spectrometry (MBMS), saturation current measurements, and detailed kinetic modeling supported by quantum chemistry calculations. Mass spectra recorded in the flame reaction zone identified a number of key flame cations, including H&lt;sub&gt;3&lt;/sub&gt;O⁺, NH&lt;sub&gt;4&lt;/sub&gt;⁺, NO⁺, HCNH⁺, CH&lt;sub&gt;2&lt;/sub&gt;NH&lt;sub&gt;2&lt;/sub&gt;⁺, CH&lt;sub&gt;3&lt;/sub&gt;NH&lt;sub&gt;3&lt;/sub&gt;⁺, C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;3&lt;/sub&gt;NH&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, H&lt;sub&gt;2&lt;/sub&gt;NCO⁺, CHN&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;4&lt;/sub&gt;⁺ and C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;5&lt;/sub&gt;NH&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, as well as their ammonia and water clusters formed during sampling. Saturation current measurements confirmed the CH + O pathway as the primary route of chemiionization, leading to the selection of the Zhang et al. mechanism (Fuel 341 (2023) 127676) as the optimal neutral chemistry basis. Based on the experimental findings, a comprehensive ion-chemistry mechanism was constructed by merging previously developed models for hydrocarbon flames and for the carbon-free NH&lt;sub&gt;3&lt;/sub&gt;/H&lt;sub&gt;2&lt;/sub&gt; system, and extending them with reactions for the identified nitrogen-carbon cations. The proposed mechanism reproduces the spatial profiles of the major cations and captures key experimental trends. Notably, the inclusion of HONO-mediated pathways proved essential for correctly predicting NO&lt;sup&gt;+&lt;/sup&gt; formation in the post-flame zone, a significant improvement over previous mechanisms that substantially underestimated NO&lt;sup&gt;+&lt;/sup&gt; abundance. These results provide detailed insight into the coupled N–C–H–O ion chemistry in ammonia-methane flames and establish a foundation for simulation of ion currents and behavior of electrified flames, and the development of ion-based diagnostics and control strategies for ammonia-fueled combustion systems.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;Novelty and significance statement&lt;/strong&gt;&lt;/div&gt;&lt;div&gt;This study presents the first comprehensive investigation of positive ion chemistry in NH&lt;sub&gt;3&lt;/sub&gt;/CH&lt;sub&gt;4&lt;/sub&gt; flames. Multiple cations specific to ammonia-methane combustion are identified by molecular beam mass spectrometry, and their structural and thermochemical characterization is provided using high-accuracy quantum chemical calculations. An ion chemistry mechanism, validated against measured spatial distributions of ions and saturation currents, offers novel insights into ion formation pathways during the combustion of ammonia-methane blends. The significance of this work lies in enabling ion-based technologies for ammonia-methane combustion, a promising low-carbon energy solution. By identifying key ions and providing the first validated ion chemistry mechanism for an H&lt;img&gt;C-O&lt;img&gt;N system, we estab","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106222"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148582496","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}