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Flame mode transitions in outer recirculation zone of lean premixed prevaporized n-decane/air swirling flames

Experimental Thermal and Fluid Science 2025年 168卷

作者： Lin, Wenjun Zhang, Weijie Liu, Hongfang Gao, Zhihao Cai, Xiao Wang, Jinhua Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center Mianyang621000 China

The outer recirculation zone (ORZ) flame modes and their transition were experimentally investigated in lean premixed prevaporized n-decane/air swirling flames. The flame structure and flow field were measured employing simultaneous CH2O/OH-PLIF and OH-PLIF/PIV laser diagnostics. The ORZ temperature was estimated with thermocouples. Three ORZ flame modes were identified: (1) mode II, characterized by extensive CH2O but nearly absent OH in the ORZ;(2) mode III, with flickering CH2O and OH in the ORZ;(3) mode IV, with flickering OH in the ORZ but nearly without CH2O. Besides, the mode I is defined as the inner shear layer (ISL) flame and mode V is the ISL/outer shear layer (OSL) flame. A theoretical diagram from mode I to V is achieved describing transition from the ISL to ISL/OSL flames. It is confirmed that the presence of CH2O in the ORZ results from the first-stage low-temperature autoignition, which is validated to be predictable with the ignition Damköhler number (Daig) after examining the fluid residence time and ignition delay time. It is found that the high-temperature ORZ flame indicated by the flickering OH radicals cannot be predicted merely using Daig. Instead, the increased flame speed and intensified ISL flame propagation into the ORZ due to the elevated equivalence ratio influence a lot, which can also be promoted by the shear layer vortices. These processes are expected to motivate the entrainment of hot burnt gas into the ORZ thus to form the high-temperature ORZ flame. The flickering ORZ flame is undesirable due to the potentially induced combustion instabilities, and this work can broaden its understanding and provide insights for its suppression. © 2025 Elsevier Inc.

关键词： Thermocouples

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A 3D-dimensional interconnected structured poly (m-phenylene isophthalamide) nanofiber separator with Li1.5Al0.5Ge1.5(PO4)3 for high-safety lithium-sulfur batteries

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Journal of power Sources 2025年 645卷

作者： Liu, Jianwei Zhu, Lei Chai, Qinqin Sun, Shiyi Yang, Xiaomeng Sun, Jingyun Zhang, Yating Zhu, Youyu Yan, Wei College of Chemistry and Chemical Engineering Xi'an University of Science and Technology Shaanxi Xi'an710054 China Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao tong University Shaanxi Xi'an710049 China Xi'an Hantang Analysis & Test Co. Ltd Shaanxi Xi'an710201 China

Safety concerns have consistently presented substantial obstacles to the widespread adoption of lithium-sulfur (Li-S) batteries. Conventional polyolefin separators, which are characterized by low flash points and insufficient mechanical strength, pose potential safety hazards, including risks of fire and explosion under extreme operating conditions. In this study, we introduce a thermally stable and non-flammable poly-m-phenyleneisophthalamide (PMIA)-based multifunctional separator (L-PMIA separator), which is enhanced with lithium aluminum germanium phosphate (Li1.5Al0.5Ge1.5(PO4)3 or LAGP) fillers. By incorporating g high-ionic-conductivity LAGP and establishing an interconnected framework, this design effectively mitigates the issues of particle agglomeration and uneven commonly ion transport associated with traditional separators. The L-PMIA separator demonstrates remarkable mechanical strength (with a tensile strength of 8.5 MPa and a puncture force of 0.72 N) and thermal stability (showing no dimensional shrinkage even at 200 °C), while also facilitating the formation of continuous ion channels that inhibit lithium dendrite growth. Consequently, Li-S batteries utilizing the 4L-PMIA separator demonstrated a reversible capacity of 4.97 mAh cm−2 after 150 cycles, even under conditions of high sulfur loading (6.75 mg cm−2), limited electrolyte availability (E/S = 7), and elevated temperatures. This approach offers novel insights for the development of future energy storage systems characterized by enhanced safety and performance. © 2025 Elsevier B.V.

关键词： Lithium sulfur batteries

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Research on control strategies for rapid load decrease events in fluoride salt reactor-supercritical CO2 Brayton cycle systems

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Nuclear engineering and Design 2025年 439卷

作者： Shichang, Yun Xinyu, Li Dalin, Zhang Ping, Song Wenxi, Tian Suizheng, Qiu Guanghui, Su State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Marine Thermal Power Technology Wuhan Second Ship Design and Research Institute Wuhan China

This study delves into the control strategies for the Fluoride-salt-cooled High-temperature Reactor-Supercritical CO2 (SCO2) Brayton cycle power generation system under rapid grid load reduction scenarios. By developing a dynamic simulation model, the system's dynamic response characteristics under rapid load changes were analyzed, and a combined control strategy emphasizing safety, speed, and economic efficiency was proposed. The research first compared the dynamic response characteristics and steady-state performance of different bypass configurations under load rejection conditions. The computational results indicate that all three bypass control systems exhibit excellent load-following capabilities, effectively responding to a 50 % load step change within 10 s. However, significant differences were observed in their steady-state thermodynamic performance: the upper cycle bypass control achieves the highest steady-state efficiency (η = 29.92 %), followed by the turbine bypass control (η = 27.50 %), with the heat source bypass control showing relatively lower efficiency (η = 26.49 %). Although the upper cycle bypass offers superior efficiency, it leads to a substantial increase in the working fluid flow through the compressor (ΔQ = 15 %) during operation, raising the risk of compressor blockage and necessitating additional flow restriction and anti-blocking interlock control systems. Considering system safety, control complexity, and engineering feasibility, the turbine bypass system, with its relative independence and lower operational risk, is deemed more suitable as the primary control strategy for load rejection conditions. Building on this, the study proposes a combined control strategy that leverages the strengths of both bypass control and inventory control. During the initial phase of rapid load reduction, the bypass control system quickly adjusts the turbine bypass valve opening to promptly respond to grid load changes, ensuring system frequency stability

关键词： Frequency stability

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Enhancing the Frequency Control Stability in Large-Scale VPPs with Limited Capacity of Fast-Response Units 19th

Enhancing the Frequency Control Stability in Large-Scale VPP...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Liang, Jun Tian, Zeyu Zhang, Penghua Zhang, Mingyue Li, Wei Liu, Huan Chong, Daotong China Nuclear Power Operation Technology Co. Ltd. Hangzhou 311215 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China China Nuclear Power Operation Management Co. Ltd. Jiaxing 314300 China

ISBN: (纸本)9789819647996

As renewable energy penetration increases, Virtual power Plants (VPPs) must not only manage energy scheduling but also ensure system security, particularly in response to frequency fluctuations. Existing research focuses on optimizing Primary Frequency Control (PFC) and developing specific control strategies for VPP units. In this study, a dynamic simulation model of a VPP was constructed, and two control systems—Energy Management System (EMS) and Capacity Coordinated Frequency Control (CCFC)—were established and optimized for better control effectiveness. The results demonstrate that the EMS designed for rapid energy storage response is better than traditional methods in responding frequency disturbances caused by rapid power demand changes. Under EMS control, the frequency nadir improved by 17.5%, and the time to reach steady-state was reduced by 77.2% during rapid power increases. Similarly, the nadir improved by 17.1%, and the steady-state time was reduced by 69.5% during power decreases. In addition, the coordinated optimization of EMS and CCFC enhances the VPP’s ability to manage large-scale power fluctuations. The safe power step adaptation range is expanded from 5 MW to 25 MW when the BESS’s dispatchable power is limited. This study highlights the potential of integrated control strategies to significantly enhance the frequency regulation and overall stability of VPPs. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Energy Management System Frequency Fluctuations Primary Frequency Control Virtual power Plant

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Effect of surface roughness on corrosion behaviour of stainless steel in supercritical CO 2

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Journal of Materials Research and Technology 2025年 36卷 4946-4954页

作者： Liyong Cao Wenyan Zhang Chongjun Jiang Hui Wang Hong An Chao Ye Jiyun Ren Xiaole Huang Lei Deng China University of Xihua Chengdu 610039 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China China University of Petroleum-Beijing Beijing 102249 China PipeChina Gansu Branch Lanzhou 730070 China Zhengzhou Yutong Group Co. Ltd. Zhengzhou 450000 China

To study the effect of surface roughness on the corrosion behavior of austenitic steels in supercritical CO 2 , the corrosion experiments were conducted on 304 and 310S stainless steels at 550 °C and 15 MPa. The corroded samples were characterized using XRD and SEM-EDS. The results demonstrate that surface roughness significantly affects the morphology and structure of the oxide films formed on 310S stainless steel. Samples prepared with varying surface roughness (grounded using from 200# to 1000# metallographic abrasive papers) showed that rougher surfaces tend to develop denser oxide layers, whereas smoother surfaces exhibit relatively loose and porous oxide films. Despite these differences in oxide structure, the overall corrosion weight gain remained largely unaffected, indicating minimal oxide shedding from 310S steel. The oxidation product is mainly Cr 2 O 3 . For 304 stainless steel, surface roughness was found to influence the composition of surface oxides. Both 200# and 1000# samples formed loose, porous oxide films prone to spallation, with the primary constituents being Fe 3 O 4 , (Fe, Cr) 3 O 4 and Fe 2 O 3 . Because the content of (Fe, Cr) 3 O 4 and Fe 3 O 4 of the former is higher, more voids appear in the oxide film, leading to spallation within the first 100 h of exposure. The rougher surface showed a more pronounced loss of oxide. But for the 600# sample, the main component is Fe 2 O 3 . Carburization was observed to intensify with increasing surface roughness in both materials. Notably, the 200# sample of 310S stainless steel exhibited more severe carburization compared to the 1000# sample of 304 stainless steel.

关键词： Supercritical CO 2 Corrosion Austenitic stainless steels Surface roughness Oxidation

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Application and Optimization of Monte Carlo Method for Simulation of Light Propagation in Biological Tissue

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Zhongguo Jiguang/Chinese Journal of Lasers 2025年第9期52卷

作者： Zhang, Hao Liu, Yifeng Wu, Wenjuan Li, Dong Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Objective The Monte Carlo (MC) method has become a cornerstone for simulation of light propagation in biological tissues, particularly for applications in laser therapy and medical imaging. However, traditional voxel-based Monte Carlo (VMC) methods often exhibit significant errors when dealing with complex curved surfaces due to the inherent limitations of structured grid discretization. By contrast, tetrahedron-based Monte Carlo (TMC) methods, based on unstructured meshes, offer better adaptability to complex geometries but incur higher computational cost. This study aims to address the trade-off between computational efficiency and accuracy in light propagation simulations by proposing a novel correction method to improve the performance of VMC in handling curved interfaces with large refractive index differences. The objective is to enhance the accuracy of VMC while maintaining its computational efficiency, making it more viable for practical biomedical applications, such as laser treatment and optical diagnosis. Methods This study compares the performance of VMC and TMC in light propagation simulations under different refractive index conditions. We propose a coordinate transformation-based correction method to reduce the errors in VMC caused by the inaccurate handling of reflection and refraction at curved interfaces. The simulations were carried out on a multi-layer skin tissue model with varying refractive index conditions;the laser light was directed at blood vessels embedded within the dermis. The correction method involves transforming the photon direction vector in a way that accounts for the curvature of the interface, thereby improving the accuracy of light photon interactions at the tissue boundaries. Simulations were conducted using MATLAB, and the results were validated through experimental cases, such as diabetic retinopathy laser treatment. The computational setup included an Intel i7-9700K processor and an NVIDIA GTX 3080 graphics card (GPU). Resu

关键词： Laser surgery

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Uncertainty and Sensitivity Analysis of Containment Aerosol Removal Under Severe Accident

SSRN

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SSRN 2025年

作者： Ou, Pingwen Chen, Yongzheng Chen, Peng Ouyang, Yong Guo, Chao Su, Guanghui China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China State Key Laboratory of Nuclear Power Safety Technology and Equipment China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

This study focuses on the uncertainty and sensitivity analysis of containment aerosol removal under severe accident conditions using the severe accident integral code ASTEC, validated by experiments carried by CNPRI, and the coupled uncertainty and sensitivity tool SUNSET. A "separated" methodology is introduced, which distinguishes between thermal-hydraulic and aerosol boundary conditions to highlight the impact of containment aerosol mechanisms. Eleven uncertainty input parameters related are selected for uncertainty propagation and the Spearman correlation coefficient is utilized to describe sensitivity. The removal factor exhibits significant variation, with peaks due to temporary enhancement of diffusiophoresis deposition caused by corium relocation and subsequent steam generation. Uncertainty in the removal factor is substantial before aerosol release termination and narrows afterward. The gravitational settling and the diffusiophoresis deposition are the most important contributors with approximately 70% and 20% deposited aerosol mass, respectively. The initial mass medium diameter, the gravitational shape factor and the agglomeration shape factor are the most influential input parameters in aerosol removal, including in-containment deposition and environmental release, and they should be considered discreetly with conservatism in source term estimation and radioactive consequence evaluation in nuclear engineering. © 2025, The Authors. All rights reserved.

关键词： Sensitivity analysis

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X-ray computed tomography (XCT) study of jetting in a fluidized bed: Effects of two-component fluidization

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Particuology 2025年 102卷 264-274页

作者： Zhong Xiang Xi Chen Shuguang Liu Theodore J. Heindel School of Energy and Environment Southeast University Nanjing 210096 China State Key Laboratory of Low-carbon Smart Coal-fired Power Generation and Ultra-clean Emission Southeast University Nanjing 210096 China Center for Multiphase Flow Research and Education and Department of Mechanical Engineering Iowa State University Ames IA 50011 USA

Fluidization of non-spherical particles is commonly found in the biomass and solid waste processing industry, and the jetting characteristic above the aeration plate is critical to the fluidization performance of these particles. In this study, cylindrical particles are used as typical non-spherical particles and co-fluidized with small bed material particles. X-ray computed tomography (XCT) is used to reconstruct the 3D structure of the aeration plate region, allowing for the identification of individual aeration jets. The effects of jet velocity ( U j ), cylindrical particle mass fraction ( ω ), cylindrical particle density ( ρ i ), and the cylindrical particle sphericity ( ϕ ) on jet shape and volume are investigated. The experimental results indicate that decreasing the cylindrical particle mass fraction ( ω ) and particle density ( ρ i ) increases the jet length ( L ), maximum jet diameter ( D ), and maximum jet volume ( V ), but have little effect on the jet half angle ( θ ). The cylindrical particle density ( ρ i ) is the most sensitive factor for jet shape, while the effect of cylinder particle sphericity ( ϕ ) on jet shape is insignificant. A correlation of jet length ( L ) in a two-component fluidized bed with cylindrical particles and bed material is proposed based on all the experimental results.

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Simulation study on mineral transformation behaviors and ash fusion characteristics during high-alkali coal combustion under deep peaking conditions

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Fuel 2025年 399卷

作者： Liu, Jiamiao Ma, Guowei Du, Yongbo Wang, Chang'an Zhao, Yonggang Wu, Wanzhu Shi, Longping Zhao, Lin Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China National Energy Group Science and Technology Research Institute Co. Ltd. Nanjing210046 China Company Xi'an710076 China Huayuan Power Plant National Energy Group Hami Coal Power Co. Ltd. Hami839000 China

The safe and efficient combustion of high-alkali coal under deep peaking conditions remains a critical research focus. Boiler operating parameters under such conditions frequently fluctuate, markedly though incompletely understood in their influence on fouling and slagging, necessitating further investigation. Here, mineral transformation and ash fusion characteristics during high-alkali coal combustion in the main combustion zone were simulated through thermodynamic equilibrium calculations, addressing its fouling issues under deep peaking conditions. Variable loads were decomposed into distinct factors for analysis due to challenges of direct simulation. Additionally, the plasma ashing method was employed to prepare ash samples. High-alkali coals with distinct properties exhibit significant variations in mineral distribution, elemental evolution, ash fusion temperature, and viscosity. Abundant fayalite (Fe2SiO4) was observed in Hongshaquan (HSQ) coal, forming stable mineral phases with other components. In Shaerhu (SEH) coal, sodium primarily exists in the gaseous phase at high temperatures, significantly contributing to fouling. Meanwhile, Jiangjunmiao (JJM) and Wucaiwan (WCW) coals demonstrate limited mineral phases but higher ash fusion temperatures, with over 30 % of iron in the gaseous phase. The mineral transformation and ash fusion behaviors in various local combustion atmospheres follow consistent trends. The formations of gaseous sodium hydroxide (NaOH(g)) and sodium oxide in the slag phase (Na2O(slag)) are promoted with weakening reducing atmospheres, while total gaseous sodium content decreases. The slag phases of calcium, magnesium, and iron increase, accompanied by a decline in ash viscosity. However, unburned carbon inversely influences mineral transformation and ash fusion characteristics compared to excess air coefficients. This research provides theoretical support for overcoming the key technical challenges associated with high-alkali coal combus

关键词： Iron analysis

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Low-energy and accelerated hydrogen release from MgH2–5 wt% NaTiOxH catalyzed hydrogen storage reactor by graphite responsive microwave

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Journal of Magnesium and Alloys 2025年

作者： Wang, Bofei Wu, Zhen Liu, Honghao Yang, Fusheng Zhang, Zaoxiao Yao, Jing Li, Qian Cao, Hujun Li, Bo State Key Laboratory of Fluorine & Nitrogen Chemicals School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow for Power Engineering Xi'an Jiaotong University Xi'an710049 China National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing400044 China Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian116023 China Faculty of Engineering Electrical Energy Management Group University of Bristol BristolBS8 1QU United Kingdom

Owing to high thermal stability and large reaction enthalpy, MgH2 has high reaction temperatures and sluggish reaction kinetics in the dehydrogenation process, which consumes lots of energy. To achieve hydrogen release with low energy consumption, accelerated reaction rate, and high heating uniformity, this paper proposes a novel method of graphite responsive microwave-assisted thermal management with NaTiOxH catalyst. A multi-physics model of the 5 wt% NaTiOxH catalyzed MgH2 reactor integrated with a microwave generator is developed to investigate the reaction, heat and mass transfer process of hydrogen release. It is found that the graphite responsive microwave heating method could improve the temperature uniformity of reaction bed, reduce the energy consumption by at least 10.71% and save the hydrogen release time by 53.49% compared with the traditional electric heating method. Moreover, the hydrogen desorption thermodynamics could be improved with the increase of microwave power. The hydrogen release time is shortened by 19.55% with the increase of 20 W microwave power. Meanwhile, it is also concluded that the microwave excitation frequency of 2.1 GHz and the graphite content of 2 wt% have better heating performance. Therefore, it can be verified that the graphite responsive microwave heating helps to low-energy and accelerated hydrogen release from MgH2 hydrogen storage reactor. © 2025

关键词： Reaction rates

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