Pub Date : 2025-12-13DOI: 10.1016/j.fuel.2025.138007
Zuochao Yu , Donghui Ci , Yong He , Junjie Jiang , Wubin Weng , Yanqun Zhu , Shixing Wang , Dayong Tian , Zhihua Wang
Ammonia, as a carbon-free fuel, offers great potential for reducing carbon emissions through co-combustion with hydrocarbons such as methane. However, in practical combustion systems, high concentrations of CO2 and NO resulting from staged combustion or flue gas recirculation (FGR) can significantly affect flame propagation and pollutant formation. In this work, the temperature, OH radical and NO distribution in laminar planar NH3/CH4/O2/NO/CO2 premixed flames established in a heat flux burner under various equivalence ratios and ammonia blending ratios were investigated using the ultraviolet broadband absorption spectroscopy (UVBAS) technique. The results confirm the accuracy of UVBAS in regions with mild gradients (e.g., post-flame zones) and successfully capture the dual role of NO—acting as an oxidizer in the pre-ignition zone and rapidly forming as the primary nitrogen oxide beyond the flame front. One-dimensional laminar flame simulations based on detailed chemical kinetic mechanisms were performed to validate the experimental data and analyze reaction pathways. While most mechanisms show good agreement in predicting laminar burning velocities (SL) and OH profiles, significant discrepancies remain in NO formation predictions. Based on sensitivity and rate-of-production (ROP) analyses combined with experimental measurements, key reaction sub-mechanisms were refined and improved.
{"title":"Experimental and kinetic study of temperature and OH/NO profiles in laminar NH3/CH4/O2/NO/CO2 premixed flames","authors":"Zuochao Yu , Donghui Ci , Yong He , Junjie Jiang , Wubin Weng , Yanqun Zhu , Shixing Wang , Dayong Tian , Zhihua Wang","doi":"10.1016/j.fuel.2025.138007","DOIUrl":"10.1016/j.fuel.2025.138007","url":null,"abstract":"<div><div>Ammonia, as a carbon-free fuel, offers great potential for reducing carbon emissions through co-combustion with hydrocarbons such as methane. However, in practical combustion systems, high concentrations of CO<sub>2</sub> and NO resulting from staged combustion or flue gas recirculation (FGR) can significantly affect flame propagation and pollutant formation. In this work, the temperature, OH radical and NO distribution in laminar planar NH<sub>3</sub>/CH<sub>4</sub>/O<sub>2</sub>/NO/CO<sub>2</sub> premixed flames established in a heat flux burner under various equivalence ratios and ammonia blending ratios were investigated using the ultraviolet broadband absorption spectroscopy (UVBAS) technique. The results confirm the accuracy of UVBAS in regions with mild gradients (e.g., post-flame zones) and successfully capture the dual role of NO—acting as an oxidizer in the pre-ignition zone and rapidly forming as the primary nitrogen oxide beyond the flame front. One-dimensional laminar flame simulations based on detailed chemical kinetic mechanisms were performed to validate the experimental data and analyze reaction pathways. While most mechanisms show good agreement in predicting laminar burning velocities (<em>S<sub>L</sub></em>) and OH profiles, significant discrepancies remain in NO formation predictions. Based on sensitivity and rate-of-production (ROP) analyses combined with experimental measurements, key reaction sub-mechanisms were refined and improved.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 138007"},"PeriodicalIF":7.5,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-13DOI: 10.1016/j.fuel.2025.137989
Abdelmola Albadwi , Saltuk Buğra Selçuklu , Mehmet Fatih Kaya
Proton exchange membrane water electrolyzers (PEMWEs) are among the most promising technologies for sustainable hydrogen production. However, optimizing their operational performance remains a critical challenge. This study investigates the combined effects of anode and cathode electrocatalyst loadings on PEMWE performance using explainable machine learning (ML) approaches. A comprehensive experimental dataset of 1344 samples, incorporating parameters such as catalyst loadings (3-4 mgIrO2 cm−2 for anode and 0.4-0.7 mgPt/C cm−2 for cathode), membrane type (Nafion 115 and Aquivion E98-09S), temperature (50-80 °C), flow rate (50-100 mL min−1), torque (2-2.5 N·m), and current density were analyzed. Four ML models, Extreme Gradient Boosting (XGBoost), Random Forest (RF), Decision Tree (DT), and Categorical Boosting (CatBoost), were trained to predict current density under varying conditions. Bayesian hyperparameter optimization was applied to enhance predictive accuracy, with the DT model achieving the best performance (R2 = 0.9594), as validated by the Wilcoxon signed-rank test. SHapley Additive exPlanations (SHAP) analysis was used to interpret model outputs, identifying temperature and cathode catalyst loading as the most influential features. A nonlinear correlation was observed between catalyst loadings and current density. Best electrochemical performance was achieved with catalyst loadings of 0.6 mgPt/C cm−2 for platinum-carbon (Pt/C) composite at the cathode and optimized IrO2 loading at the anode. Furthermore, a cost-performance trade-off analysis revealed the most efficient configuration, offering a 14.8 % improvement in performance at reduced material cost. This study demonstrates the potential of explainable ML in guiding the design and optimization of PEMWEs, providing a data-driven framework for enhancing hydrogen production efficiency.
质子交换膜水电解槽（PEMWEs）是最有前途的可持续制氢技术之一。然而，优化它们的运行性能仍然是一个关键的挑战。本研究使用可解释的机器学习（ML）方法研究了阳极和阴极电催化剂负载对PEMWE性能的综合影响。对1344个样品的综合实验数据集进行了分析，包括催化剂负载（阳极为3-4 mgIrO2 cm -2，阴极为0.4-0.7 mgPt/C cm -2）、膜类型（Nafion 115和aquvion E98-09S）、温度（50-80°C）、流速（50-100 mL min -1）、扭矩（2-2.5 N·m）和电流密度等参数。四个ML模型，极端梯度增强（XGBoost），随机森林（RF），决策树（DT）和分类增强（CatBoost），被训练来预测不同条件下的电流密度。采用贝叶斯超参数优化方法提高预测精度，DT模型的预测效果最佳（R2 = 0.9594），经Wilcoxon有符号秩检验验证。SHapley加性解释（SHAP）分析用于解释模型输出，确定温度和阴极催化剂负载是最具影响力的特征。催化剂负载与电流密度之间存在非线性关系。当铂碳（Pt/C）复合材料的阴极催化剂负载为0.6 mgPt/C cm−2，阳极催化剂负载为优化后的IrO2时，电化学性能最佳。此外，成本-性能权衡分析揭示了最有效的配置，在降低材料成本的情况下，性能提高了14.8%。该研究证明了可解释ML在指导PEMWEs设计和优化方面的潜力，为提高氢气生产效率提供了数据驱动的框架。
{"title":"Performance prediction of proton exchange membrane water electrolyzers using explainable machine learning: effects of varying anode and cathode catalyst loadings","authors":"Abdelmola Albadwi , Saltuk Buğra Selçuklu , Mehmet Fatih Kaya","doi":"10.1016/j.fuel.2025.137989","DOIUrl":"10.1016/j.fuel.2025.137989","url":null,"abstract":"<div><div>Proton exchange membrane water electrolyzers (PEMWEs) are among the most promising technologies for sustainable hydrogen production. However, optimizing their operational performance remains a critical challenge. This study investigates the combined effects of anode and cathode electrocatalyst loadings on PEMWE performance using explainable machine learning (ML) approaches. A comprehensive experimental dataset of 1344 samples, incorporating parameters such as catalyst loadings (3-4 mg<sub>IrO2</sub> cm<sup>−2</sup> for anode and 0.4-0.7 mg<sub>Pt/C</sub> cm<sup>−2</sup> for cathode), membrane type (Nafion 115 and Aquivion E98-09S), temperature (50-80 °C), flow rate (50-100 mL min<sup>−1</sup>), torque (2-2.5 N·m), and current density were analyzed. Four ML models, Extreme Gradient Boosting (XGBoost), Random Forest (RF), Decision Tree (DT), and Categorical Boosting (CatBoost), were trained to predict current density under varying conditions. Bayesian hyperparameter optimization was applied to enhance predictive accuracy, with the DT model achieving the best performance (R<sup>2</sup> = 0.9594), as validated by the Wilcoxon signed-rank test. SHapley Additive exPlanations (SHAP) analysis was used to interpret model outputs, identifying temperature and cathode catalyst loading as the most influential features. A nonlinear correlation was observed between catalyst loadings and current density. Best electrochemical performance was achieved with catalyst loadings of 0.6 mg<sub>Pt/C</sub> cm<sup>−2</sup> for platinum-carbon (Pt/C) composite at the cathode and optimized IrO<sub>2</sub> loading at the anode. Furthermore, a cost-performance trade-off analysis revealed the most efficient configuration, offering a 14.8 % improvement in performance at reduced material cost. This study demonstrates the potential of explainable ML in guiding the design and optimization of PEMWEs, providing a data-driven framework for enhancing hydrogen production efficiency.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 137989"},"PeriodicalIF":7.5,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.137969
Qi Liu , Minglu Dai , Tao Zhang , Bin Shi , Hui Zhang , Tianren Fu , Lin Li , Lunbo Duan
Real-time and accurate dynamic temperature distribution reconstruction is crucial for industrial processes. To address the challenges of improving both temporal and spatial resolution in acoustic tomography temperature reconstruction, this study introduces a virtual microphone array (VM) method. This method expands the acoustic path matrix and Time-of-Flight (TOF) matrix, effectively mitigating the issue of underdetermined equations caused by enhanced discretization in reconstruction, thereby improving spatial resolution in the reconstructed region. Additionally, a hybrid deep neural network model, the TOF Temperature Reconstruction Network (TTR-Net), is developed to overcome the prolonged reconstruction time associated with matrix expansion. Numerical simulations and experimental results demonstrate that the VM method significantly enhances reconstruction quality and spatial resolution. Compared to the original approach, the average reconstruction error is reduced by 2.405%, and spatial resolution is improved by a factor of 49. The TTR-Net, built on the VM array, demonstrates superior noise resistance and stability, achieving an average reconstruction error of 4.694% when compared to a 64-channel thermocouple array, with a more concentrated error distribution. The integrated acoustic tomography framework, combining the VM array with TTR-Net, reduces reconstruction time by two orders of magnitude and lowers reconstruction error by a factor of 2.51 compared to conventional methods. This methodology enables industrial-grade, high spatiotemporal resolution temperature field reconstruction.
{"title":"High spatiotemporal resolution acoustic tomography based on virtual microphone array and hybrid deep learning","authors":"Qi Liu , Minglu Dai , Tao Zhang , Bin Shi , Hui Zhang , Tianren Fu , Lin Li , Lunbo Duan","doi":"10.1016/j.fuel.2025.137969","DOIUrl":"10.1016/j.fuel.2025.137969","url":null,"abstract":"<div><div>Real-time and accurate dynamic temperature distribution reconstruction is crucial for industrial processes. To address the challenges of improving both temporal and spatial resolution in acoustic tomography temperature reconstruction, this study introduces a virtual microphone array (VM) method. This method expands the acoustic path matrix and Time-of-Flight (TOF) matrix, effectively mitigating the issue of underdetermined equations caused by enhanced discretization in reconstruction, thereby improving spatial resolution in the reconstructed region. Additionally, a hybrid deep neural network model, the TOF Temperature Reconstruction Network (TTR-Net), is developed to overcome the prolonged reconstruction time associated with matrix expansion. Numerical simulations and experimental results demonstrate that the VM method significantly enhances reconstruction quality and spatial resolution. Compared to the original approach, the average reconstruction error is reduced by 2.405%, and spatial resolution is improved by a factor of 49. The TTR-Net, built on the VM array, demonstrates superior noise resistance and stability, achieving an average reconstruction error of 4.694% when compared to a 64-channel thermocouple array, with a more concentrated error distribution. The integrated acoustic tomography framework, combining the VM array with TTR-Net, reduces reconstruction time by two orders of magnitude and lowers reconstruction error by a factor of 2.51 compared to conventional methods. This methodology enables industrial-grade, high spatiotemporal resolution temperature field reconstruction.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 137969"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.138001
Junxuan Huang, Yanfen Liao, Hailong Yang, Zejie Zheng, Xiaoqian Ma
Red mud (RM), an iron-based industrial solid waste, holds potential as an oxygen carriers (OCs) for biomass chemical looping gasification due to its low cost. To enhance the reactivity of red mud, this paper proposed a modification scheme involving co-doping with spent lithium-ion battery cathode materials. The study investigated the optimal doping amount to achieve maximum gasification reactivity under specific conditions for the modified red mud. The steam/carbon ratio for steam reforming was optimized to achieve maximum syngas yield and stability of the oxygen carrier during redox cycling. Compared to raw RM, the modified RM-20CM exhibited increased specific surface area and greater numbers of active sites. A nickel–iron bimetallic synergistic effect enhanced oxygen vacancy concentration within the oxygen carriers, thereby improving oxygen mobility. The stable lattice template enabled the OCs to maintain high OCs activity throughout gasification cycles, while added cobalt-manganese oxide catalyzed light hydrocarbon cracking. Over 10 gasification cycles, RM-20CM sustained consistent syngas yield (1470.5 mL/g), carbon conversion efficiency (82.7 %), and cold gas efficiency (93.8 %).
{"title":"Improvement of red mud oxygen carriers in biomass chemical looping gasification using battery cathode materials doping","authors":"Junxuan Huang, Yanfen Liao, Hailong Yang, Zejie Zheng, Xiaoqian Ma","doi":"10.1016/j.fuel.2025.138001","DOIUrl":"10.1016/j.fuel.2025.138001","url":null,"abstract":"<div><div>Red mud (RM), an iron-based industrial solid waste, holds potential as an oxygen carriers (OCs) for biomass chemical looping gasification due to its low cost. To enhance the reactivity of red mud, this paper proposed a modification scheme involving co-doping with spent lithium-ion battery cathode materials. The study investigated the optimal doping amount to achieve maximum gasification reactivity under specific conditions for the modified red mud. The steam/carbon ratio for steam reforming was optimized to achieve maximum syngas yield and stability of the oxygen carrier during redox cycling. Compared to raw RM, the modified RM-20CM exhibited increased specific surface area and greater numbers of active sites. A nickel–iron bimetallic synergistic effect enhanced oxygen vacancy concentration within the oxygen carriers, thereby improving oxygen mobility. The stable lattice template enabled the OCs to maintain high OCs activity throughout gasification cycles, while added cobalt-manganese oxide catalyzed light hydrocarbon cracking. Over 10 gasification cycles, RM-20CM sustained consistent syngas yield (1470.5 mL/g), carbon conversion efficiency (82.7 %), and cold gas efficiency (93.8 %).</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 138001"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.137976
Jiexin Hou , Yunkai Ji , Ermeng Zhao
Low reservoir permeability and insufficient thermal energy are the main factors limiting the gas production rate of low-permeability hydrate bearing layers (HBLs) developed by depressurization. In this paper, a method combining reservoir stimulation with low-frequency electric field heating is proposed for the development of such reservoirs. On this basis, a mathematical model for reservoir stimulation-assisted electric heating development was constructed by integrating the discrete fracture method, the current continuity equation, and hydrate phase equilibrium and kinetic equations. The production capacity and the evolution of physical fields under different development methods were compared based on numerical simulation results. The study indicates that reservoir stimulation can significantly accelerate the depressurization rate of the reservoir and the dissociation rate of hydrates, increasing production by up to 170.1 % compared to depressurization alone. Electric heating can rapidly supplement thermal energy in the later stages of depressurization when heat is largely depleted, promoting hydrate dissociation and further increasing production by 39.4 % compared to reservoir stimulation-assisted depressurization. The energy consumption analysis shows that the energy efficiency of implementing low-frequency electric field heating can reach 14.4. The use of electric heating for developing low-permeability HBLs can not only substantially increase production capacity but also achieve excellent energy utilization efficiency.
{"title":"A study on the numerical simulation method for developing low-permeability natural gas hydrate reservoirs with reservoir stimulation-assisted electric heating","authors":"Jiexin Hou , Yunkai Ji , Ermeng Zhao","doi":"10.1016/j.fuel.2025.137976","DOIUrl":"10.1016/j.fuel.2025.137976","url":null,"abstract":"<div><div>Low reservoir permeability and insufficient thermal energy are the main factors limiting the gas production rate of low-permeability hydrate bearing layers (HBLs) developed by depressurization. In this paper, a method combining reservoir stimulation with low-frequency electric field heating is proposed for the development of such reservoirs. On this basis, a mathematical model for reservoir stimulation-assisted electric heating development was constructed by integrating the discrete fracture method, the current continuity equation, and hydrate phase equilibrium and kinetic equations. The production capacity and the evolution of physical fields under different development methods were compared based on numerical simulation results. The study indicates that reservoir stimulation can significantly accelerate the depressurization rate of the reservoir and the dissociation rate of hydrates, increasing production by up to 170.1 % compared to depressurization alone. Electric heating can rapidly supplement thermal energy in the later stages of depressurization when heat is largely depleted, promoting hydrate dissociation and further increasing production by 39.4 % compared to reservoir stimulation-assisted depressurization. The energy consumption analysis shows that the energy efficiency of implementing low-frequency electric field heating can reach 14.4. The use of electric heating for developing low-permeability HBLs can not only substantially increase production capacity but also achieve excellent energy utilization efficiency.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 137976"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.138000
Zhaohui Sui , Qian Xu , Jing Cheng , Cheng Zhang , Yilin Chen , Kankan Liu , Shiwen Lei , Lixin Zhang , Fengbo Guo
Hydrogen energy, due to its renewable and sustainable nature, has become an inevitable choice for addressing energy shortages and ensuring sustainable human development. By regulating the electronic structure and self-adjusting mechanisms between transition metal atoms, electrocatalytic activity can be effectively enhanced. Here, Mn-CoFeSe2 was synthesized as a highly efficient bifunctional electrocatalyst with accelerated charge transfer kinetics by Mn doped and selenization reaction of layered double hydroxide CoFe-LDH. Results demonstrate that Mn-CoFeSe2 exhibits outstanding electrocatalytic activity and stability under alkaline conditions: HER overpotentials at 10 and 100 mA cm−2 are 141 mV and 286 mV, respectively, while OER overpotentials are 174 mV and 261 mV. When assembled into overall water splitting electrolyzer, it required only 1.54 V cell potential at a current density of 10 mA cm−2, with current density remaining essentially unchanged during 200 h of stability testing. The introduction of Mn induces a localized electronic restructuring in Mn-CoFeSe2 due to Mn’s strong electron-withdrawing effect, causing electron transfer from Fe to Mn. This electronic rearrangement between Co, Fe, and Mn atoms modifies the electronic structure of Mn-CoFeSe2, thereby enhancing charge transport. Following selenization, Se atoms transfer electrons to the Co, Fe, and Mn metal centers, strengthening the covalent nature of the metal-selenium bonds and thereby optimizing the electronic structure of the catalytic active sites. Thin-striped nanosheets expose more active sites, while the interwoven cluster structures formed by these sheets facilitate charge transport and transfer, significantly enhancing electrochemical activity for overall water splitting. This study provides an effective approach for developing highly efficient, environmentally friendly, a transition metal-based layered selenide catalyst for sustained and stable overall water splitting.
氢能具有可再生、可持续的特点，已成为解决能源短缺、保障人类可持续发展的必然选择。通过调节过渡金属原子间的电子结构和自调节机制，可以有效地提高电催化活性。本文通过层状双氢氧化物fe - ldh的Mn掺杂和硒化反应，合成了具有加速电荷转移动力学的高效双功能电催化剂Mn- cofese2。结果表明，Mn-CoFeSe2在碱性条件下表现出良好的电催化活性和稳定性：10和100 mA cm−2下的HER过电位分别为141 mV和286 mV，而OER过电位分别为174 mV和261 mV。当组装成整体的水分解电解槽时，仅需1.54 V的电池电位，电流密度为10 mA cm - 2，在200 h的稳定性测试中电流密度基本保持不变。Mn的引入引起了Mn- cofese2的局部电子重构，这是由于Mn的强吸电子效应，导致电子从Fe转移到Mn。Co， Fe和Mn原子之间的电子重排改变了Mn- cofese2的电子结构，从而增强了电荷输运。硒化后，Se原子将电子转移到Co、Fe和Mn金属中心，加强了金属-硒键的共价键性质，从而优化了催化活性位点的电子结构。薄条纹纳米片暴露出更多的活性位点，而这些纳米片形成的相互交织的团簇结构促进了电荷的传递和转移，显著提高了整体水分解的电化学活性。该研究为开发高效、环保的过渡金属基层状硒化物催化剂提供了有效途径。
{"title":"Coupling interface constructions of clustered Mn-CoFeSe2 derived from CoFe-LDH for efficient overall water splitting","authors":"Zhaohui Sui , Qian Xu , Jing Cheng , Cheng Zhang , Yilin Chen , Kankan Liu , Shiwen Lei , Lixin Zhang , Fengbo Guo","doi":"10.1016/j.fuel.2025.138000","DOIUrl":"10.1016/j.fuel.2025.138000","url":null,"abstract":"<div><div>Hydrogen energy, due to its renewable and sustainable nature, has become an inevitable choice for addressing energy shortages and ensuring sustainable human development. By regulating the electronic structure and self-adjusting mechanisms between transition metal atoms, electrocatalytic activity can be effectively enhanced. Here, Mn-CoFeSe<sub>2</sub> was synthesized as a highly efficient bifunctional electrocatalyst with accelerated charge transfer kinetics by Mn doped and selenization reaction of layered double hydroxide CoFe-LDH. Results demonstrate that Mn-CoFeSe<sub>2</sub> exhibits outstanding electrocatalytic activity and stability under alkaline conditions: HER overpotentials at 10 and 100 mA cm<sup>−2</sup> are 141 mV and 286 mV, respectively, while OER overpotentials are 174 mV and 261 mV. When assembled into overall water splitting electrolyzer, it required only 1.54 V cell potential at a current density of 10 mA cm<sup>−2</sup>, with current density remaining essentially unchanged during 200 h of stability testing. The introduction of Mn induces a localized electronic restructuring in Mn-CoFeSe<sub>2</sub> due to Mn’s strong electron-withdrawing effect, causing electron transfer from Fe to Mn. This electronic rearrangement between Co, Fe, and Mn atoms modifies the electronic structure of Mn-CoFeSe<sub>2</sub>, thereby enhancing charge transport. Following selenization, Se atoms transfer electrons to the Co, Fe, and Mn metal centers, strengthening the covalent nature of the metal-selenium bonds and thereby optimizing the electronic structure of the catalytic active sites. Thin-striped nanosheets expose more active sites, while the interwoven cluster structures formed by these sheets facilitate charge transport and transfer, significantly enhancing electrochemical activity for overall water splitting. This study provides an effective approach for developing highly efficient, environmentally friendly, a transition metal-based layered selenide catalyst for sustained and stable overall water splitting.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 138000"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.138002
Pablo Comendador , Maria Cortazar , Maite Artetxe , Laura Santamaria , Martin Olazar , Gartzen Lopez
Sorption Enhanced Steam Reforming (SESR) is a promising approach for upgrading the process of biomass Pyrolysis and in line Steam Reforming (PY-SR), although it entails higher operational complexity. Thus, different alternatives for SESR cyclic operation were addressed in this study. Fixed and fluidized bed operating regimes, as well as several sorbent to catalyst ratios, were analyzed. The expansion of the fluidized bed constrained the sorbent to catalyst ratio, with a maximum value allowable of 1. Small concentrations of CO and CH4 were identified during the pre-breakthrough period in the fluidized bed due to a rather poor coupling between the catalyst and the sorbent. Fixed bed allowed using sorbent to catalyst ratios of up to 3, thus resulting in higher pre-breakthrough periods with H2 productions close to the theoretical value (0.1183 gH2 g−1biomass) and H2 purities close to 100 mol% in the 1st cycle. After three operation cycles, the catalyst was more deactivated as the sorbent to catalyst ratio was higher. The deactivation was attributed to the reaction between the CaO in the sorbent and the Al2O3 in the catalyst, giving rise to the formation of variable amounts of calcium aluminates in the catalyst.
吸附强化蒸汽重整（SESR）是生物质热解和在线蒸汽重整（PY-SR）过程升级的一种有前途的方法，尽管它需要更高的操作复杂性。因此，本研究提出了不同的SESR循环操作方案。分析了固定床和流化床的操作制度，以及几种吸附剂与催化剂的比例。流化床的膨胀限制了吸附剂与催化剂的比例，允许的最大值为1。由于催化剂和吸附剂之间的耦合较差，在突破前的流化床中发现了低浓度的CO和CH4。固定床允许使用吸附剂与催化剂的比例高达3，从而产生更长的突破前周期，H2产量接近理论值（0.1183 gH2 g - 1biomass），第一个循环的H2纯度接近100 mol%。经过3次循环后，随着吸附剂与催化剂比例的增加，催化剂失活程度越高。失活是由于吸附剂中的CaO与催化剂中的Al2O3发生反应，在催化剂中形成了不同数量的铝酸钙。
{"title":"Insights into the cyclic operation of sorption enhanced steam reforming of biomass pyrolysis volatiles: Role of contact mode and sorbent to catalyst ratio","authors":"Pablo Comendador , Maria Cortazar , Maite Artetxe , Laura Santamaria , Martin Olazar , Gartzen Lopez","doi":"10.1016/j.fuel.2025.138002","DOIUrl":"10.1016/j.fuel.2025.138002","url":null,"abstract":"<div><div>Sorption Enhanced Steam Reforming (SESR) is a promising approach for upgrading the process of biomass Pyrolysis and in line Steam Reforming (PY-SR), although it entails higher operational complexity. Thus, different alternatives for SESR cyclic operation were addressed in this study. Fixed and fluidized bed operating regimes, as well as several sorbent to catalyst ratios, were analyzed. The expansion of the fluidized bed constrained the sorbent to catalyst ratio, with a maximum value allowable of 1. Small concentrations of CO and CH<sub>4</sub> were identified during the pre-breakthrough period in the fluidized bed due to a rather poor coupling between the catalyst and the sorbent. Fixed bed allowed using sorbent to catalyst ratios of up to 3, thus resulting in higher pre-breakthrough periods with H<sub>2</sub> productions close to the theoretical value (0.1183 g<sub>H2</sub> g<sup>−1</sup><sub>biomass</sub>) and H<sub>2</sub> purities close to 100 mol% in the 1<sup>st</sup> cycle. After three operation cycles, the catalyst was more deactivated as the sorbent to catalyst ratio was higher. The deactivation was attributed to the reaction between the CaO in the sorbent and the Al<sub>2</sub>O<sub>3</sub> in the catalyst, giving rise to the formation of variable amounts of calcium aluminates in the catalyst.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 138002"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.137941
Yaozong Duan , Dong Han , Fashe Li , Hua Wang
Prenol (3-methyl-2-buten-1-ol) has been considered as a potential additive to gasoline, due to its unique octane hyperboosting feature when blended with commercial gasoline or primary reference fuels. However, such an interesting feature was absent in its isomer counterpart, i.e., iso-prenol (3-methyl-3-buten-1-ol). To reveal the potential reasons of this unique feature, it is essential to gain a better understanding of the combustion chemistry for prenol and iso-prenol. In this work, a comprehensive study on the reaction kinetics of hydrogen abstraction reactions from prenol isomers by hydrogen atom was performed with high-level quantum chemical calculation method. The single point energies for reaction species were calculated at CCSD(T)/CBS level of theory, with optimized geometries of the lowest-energy conformers determined at M06-2X/6–311+G(2df,2p) level of theory. The rate coefficients in 400-2000 K temperatures were calculated using the canonical variational transition state theory with multistructural torsional anharmonicity and small-curvature tunneling corrections. Special attentions were paid to the effects of fuel structures, including the presence and location of C=C bond and hydroxyl moiety, via demonstrating a thorough comparison with the theoretical calculations for iso-pentanol and alkene counterparts of prenol isomers reported in the literature. Temperature-dependent thermochemical parameters of prenol isomers and their fuel radicals were derived from the multistructural partition functions, together with the standard formation enthalpies determined with the isodesmic reaction method. Rate coefficients and thermochemistry were incorporated into the kinetic models of prenol isomers to investigate their influence on the performance of prenol/iso-prenol oxidation and pyrolysis. This study provides a better understanding on the combustion chemistry of prenol isomers and reactions between unsaturated alcohols and H atom.
{"title":"Towards a better understanding of the combustion chemistry for prenol and iso-prenol: An ab initio kinetic study on hydrogen abstraction reactions by hydrogen atom","authors":"Yaozong Duan , Dong Han , Fashe Li , Hua Wang","doi":"10.1016/j.fuel.2025.137941","DOIUrl":"10.1016/j.fuel.2025.137941","url":null,"abstract":"<div><div>Prenol (3-methyl-2-buten-1-ol) has been considered as a potential additive to gasoline, due to its unique octane hyperboosting feature when blended with commercial gasoline or primary reference fuels. However, such an interesting feature was absent in its isomer counterpart, i.e., <em>iso</em>-prenol (3-methyl-3-buten-1-ol). To reveal the potential reasons of this unique feature, it is essential to gain a better understanding of the combustion chemistry for prenol and <em>iso</em>-prenol. In this work, a comprehensive study on the reaction kinetics of hydrogen abstraction reactions from prenol isomers by hydrogen atom was performed with high-level quantum chemical calculation method. The single point energies for reaction species were calculated at CCSD(T)/CBS level of theory, with optimized geometries of the lowest-energy conformers determined at M06-2X/6–311+G(2df,2p) level of theory. The rate coefficients in 400-2000 K temperatures were calculated using the canonical variational transition state theory with multistructural torsional anharmonicity and small-curvature tunneling corrections. Special attentions were paid to the effects of fuel structures, including the presence and location of C=C bond and hydroxyl moiety, via demonstrating a thorough comparison with the theoretical calculations for <em>iso</em>-pentanol and alkene counterparts of prenol isomers reported in the literature. Temperature-dependent thermochemical parameters of prenol isomers and their fuel radicals were derived from the multistructural partition functions, together with the standard formation enthalpies determined with the isodesmic reaction method. Rate coefficients and thermochemistry were incorporated into the kinetic models of prenol isomers to investigate their influence on the performance of prenol/<em>iso</em>-prenol oxidation and pyrolysis. This study provides a better understanding on the combustion chemistry of prenol isomers and reactions between unsaturated alcohols and H atom.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 137941"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.138006
Jian Zheng, Haiou Wang, Kun Luo, Jianren Fan
In the present work, direct numerical simulations (DNS) were performed to understand the effect of body force on the stability and NO formation in lean hydrogen-enriched ammonia premixed flames. In the linear regime, two-dimensional DNS were conducted under various body force conditions. It was found that the effect of body force on the linear growth rate is negligible when Fr > 1 and becomes significant when Fr < 1, with Fr being the Froude number defined as , where is the body force magnitude, is the laminar flame speed and is the flame thickness. In the nonlinear regime, three-dimensional DNS were carried out with two different Froude numbers, i.e. Fr = 10 and Fr = 0.033. Both laminar and turbulent flames were considered. The flame consumption speed in the low Fr cases are much higher than that in the high Fr cases, which is primarily due to the increase of flame area. Under laminar conditions, the flame morphology and flame curvature differ significantly between the high and low Fr cases, while the differences become less pronounced for the turbulent cases. The distributions of flame displacement speed and flame stretch along the flame front were analyzed, which are closely related to the flame curvature. The NO formation characteristics were examined, and it was shown that the mass fraction of NO within the flame brush is higher in the low Fr cases, attributed to a wider range of high-temperature region related to superadiabatic combustion. The diagram of global nitrogen flow was analyzed, revealing that both the body force and turbulence rarely change the shares of various nitrogen pathways. The impact of curvature on NO pathways was also explored, showing that the production rate of various NO pathways is significantly enhanced in positively curved regions compared with that in negatively curved regions.
{"title":"The characteristics of stability and NO formation in lean hydrogen-enriched ammonia premixed flames with varying body force","authors":"Jian Zheng, Haiou Wang, Kun Luo, Jianren Fan","doi":"10.1016/j.fuel.2025.138006","DOIUrl":"10.1016/j.fuel.2025.138006","url":null,"abstract":"<div><div>In the present work, direct numerical simulations (DNS) were performed to understand the effect of body force on the stability and NO formation in lean hydrogen-enriched ammonia premixed flames. In the linear regime, two-dimensional DNS were conducted under various body force conditions. It was found that the effect of body force on the linear growth rate is negligible when <em>Fr</em> > 1 and becomes significant when <em>Fr</em> < 1, with <em>Fr</em> being the Froude number defined as <span><math><mrow><msubsup><mi>S</mi><mrow><mi>L</mi></mrow><mn>2</mn></msubsup><mo>/</mo><mi>g</mi><msub><mi>δ</mi><mi>L</mi></msub></mrow></math></span>, where <span><math><mrow><mi>g</mi></mrow></math></span> is the body force magnitude, <span><math><mrow><msub><mi>S</mi><mi>L</mi></msub></mrow></math></span> is the laminar flame speed and <span><math><mrow><msub><mi>δ</mi><mi>L</mi></msub></mrow></math></span> is the flame thickness. In the nonlinear regime, three-dimensional DNS were carried out with two different Froude numbers, i.e. <em>Fr</em> = 10 and <em>Fr</em> = 0.033. Both laminar and turbulent flames were considered. The flame consumption speed in the low <em>Fr</em> cases are much higher than that in the high <em>Fr</em> cases, which is primarily due to the increase of flame area. Under laminar conditions, the flame morphology and flame curvature differ significantly between the high and low <em>Fr</em> cases, while the differences become less pronounced for the turbulent cases. The distributions of flame displacement speed and flame stretch along the flame front were analyzed, which are closely related to the flame curvature. The NO formation characteristics were examined, and it was shown that the mass fraction of NO within the flame brush is higher in the low <em>Fr</em> cases, attributed to a wider range of high-temperature region related to superadiabatic combustion. The diagram of global nitrogen flow was analyzed, revealing that both the body force and turbulence rarely change the shares of various nitrogen pathways. The impact of curvature on NO pathways was also explored, showing that the production rate of various NO pathways is significantly enhanced in positively curved regions compared with that in negatively curved regions.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 138006"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.fuel.2025.137884
Shania Sánchez , David Santalices , Jesús Belmar , Nuria Verastegui , Susana Briz , Juan Meléndez
This work presents an experimental methodology for the quantification of unburned methane (CH4) flow in laboratory-scale air assisted flares. The approach relies on the use of a mid-infrared hyperspectral Fourier Transform Infrared (FTIR) imaging system operated in absorption mode, in combination with a gas capture setup that ensures complete extraction of combustion products. The extracted gases are directed through a T-shaped tube with an extended optical path, where their transmittance spectra are recorded and fitted to a radiative transfer model to retrieve CH4 column densities. The core of the method is a calibration procedure that establishes a relationship between these column densities and mass flow rates by releasing known CH4 flows through the burner and measuring the corresponding column densities in the tube. The methodology is applied to assess the performance in terms of the CH4 destruction and removal efficiency (DRE) of a flare under different levels of air assistance and crosswind. The results reveal a critical threshold beyond which CH4 emissions increase significantly due to partial flame extinction, thus lowering the DRE, and demonstrate the method’s ability to resolve temporal variations in combustion efficiency with a time resolution of 10 s. Although developed in a controlled laboratory setting, the proposed technique provides a reliable framework for studying combustion instability and validating field-deployable remote sensing technologies. Its implementation can contribute to improving flare performance assessment and to the mitigation of methane emissions from industrial combustion sources.
{"title":"Measurement of unburned methane in air-assisted flares using FTIR absorption spectroscopy on extracted gases","authors":"Shania Sánchez , David Santalices , Jesús Belmar , Nuria Verastegui , Susana Briz , Juan Meléndez","doi":"10.1016/j.fuel.2025.137884","DOIUrl":"10.1016/j.fuel.2025.137884","url":null,"abstract":"<div><div>This work presents an experimental methodology for the quantification of unburned methane (CH<sub>4</sub>) flow in laboratory-scale air assisted flares. The approach relies on the use of a mid-infrared hyperspectral Fourier Transform Infrared (FTIR) imaging system operated in absorption mode, in combination with a gas capture setup that ensures complete extraction of combustion products. The extracted gases are directed through a T-shaped tube with an extended optical path, where their transmittance spectra are recorded and fitted to a radiative transfer model to retrieve CH<sub>4</sub> column densities. The core of the method is a calibration procedure that establishes a relationship between these column densities and mass flow rates by releasing known CH<sub>4</sub> flows through the burner and measuring the corresponding column densities in the tube. The methodology is applied to assess the performance in terms of the CH<sub>4</sub> destruction and removal efficiency (DRE<span><math><mrow><msub><mtext>CH</mtext><mrow><mn>4</mn></mrow></msub></mrow></math></span>) of a flare under different levels of air assistance and crosswind. The results reveal a critical threshold beyond which CH<sub>4</sub> emissions increase significantly due to partial flame extinction, thus lowering the DRE<span><math><mrow><msub><mtext>CH</mtext><mrow><mn>4</mn></mrow></msub></mrow></math></span>, and demonstrate the method’s ability to resolve temporal variations in combustion efficiency with a time resolution of 10 s. Although developed in a controlled laboratory setting, the proposed technique provides a reliable framework for studying combustion instability and validating field-deployable remote sensing technologies. Its implementation can contribute to improving flare performance assessment and to the mitigation of methane emissions from industrial combustion sources.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"410 ","pages":"Article 137884"},"PeriodicalIF":7.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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