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Modeling and Performance Analysis on an Integrated System Combining Supercritical Carbon Dioxide Brayton Cycle with Leakage Feedback Utilizing a Heat Pump or Direct Compression

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Journal of Engineering for Gas Turbines and Power 2025年第10期147卷 101011页

作者： Qi, Yinke Ma, Xiaofeng Jiang, Peixue Zhu, Yinhai Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Beijing Key Laboratory of CO2 Utilization and Reduction Technology Department of Energy and Power Engineering Tsinghua University Beijing100084 China

CO2 leakage due to the coexistence of pressure differentials and clearances within the integrated turbine-Alternator-compressor (TAC) of the kW-level sCO2 Brayton cycle is a key issue affecting cycle efficiency and long-Term stable operation. To analyze the impact of leakage and feedback, this study examined the integrated system of the sCO2 Brayton cycle with leakage feedback and compared the system performance differences between heat pump feedback and direct compression feedback. Thermodynamic models for the Brayton cycle and feedback unit were established, and the effects of varying key parameters were analyzed. A genetic algorithm was employed to further optimize the system. The selection suggestion charts for the feedback unit were obtained. It is recommended to choose a direct compression feedback unit for conditions with a cavity pressure higher than 6.41 MPa, whereas a heat pump feedback unit is recommended for other conditions. The heat pump feedback unit has advantages particularly at high rotational speeds, low leakage factors, and low cavity pressures. The efficiency of the optimized integrated system is improved by up to 12.53%. The net power accounted for only 53.6% of the turbine output power, the main cycle compression power accounted for 32.1%, the TAC losses accounted for 10.7%, and the total compression power of the feedback unit accounted for 3.7%. Ignoring the internal leakage and losses of TAC can overestimate the power generation capacity of the Brayton cycle, resulting in it being only 79% of the ideal case after considering losses and power consumption. © 2025 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Brayton cycle

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Study on the effects of combustion characteristics of pyrotechnic charges on pyrotechnic shocks

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Defence technology(防务技术) 2025年第4期46卷 79-98页

作者： Jingcheng Wang Shihui Xiong Huina Mu Xiaogang Li Yuquan Wen State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

This study calculates the combustion characteristics of various gas-generating and micro gas pyrotechnic charges,including aluminium/potassium perchlorate,boron/potassium nitrate,carbon black/potassium nitrate,and silicon-based delay compositions,using thermodynamic software.A multiphase flowthermal-solid coupling model was established,and the combustion process of the pyrotechnic charges within a closed bomb was *** pyrotechnic shock generated by combustion was *** combustion pressures and pyrotechnic shocks were *** simulation results demonstrated good agreement with experimental ***,the mechanism of shock generation by the combustion of pyrotechnic charges in the closed bomb was *** effects of the combustion characteristics of the pyrotechnic charges on the resulting pyrotechnic shocks were systematically ***,the shock response spectrum of the gas-generating pyrotechnic charges is greater than that of the micro gas compositions at most frequencies,particularly in the mid-field pyrotechnic shocks(3-10 kHz).Furthermore,the pyrotechnic shocks increase approximately linearly with the impulse of the gas-generating pyrotechnic charges.

关键词： Pyrotechnic charges Pyroshock Closed bomb tests Combustion characteristics Multiphase flow-thermal-solid coupling

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Control model for burning-bubble clouds formed by confined melt-cast explosives under thermal stimulation

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Defence technology 2025年 48卷 268-283页

作者： Li, Zhi Duan, Zhuoping Bai, Zhiling Jiao, Jixuan Xu, Liji Zhang, Liansheng Huang, Fenglei State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing100081 China

DNAN-based insensitive melt-cast explosives have been widely utilized in insensitive munition in recent years. When constrained DNAN-based melt-cast explosives are ignited under thermal stimulation, the base explosive exists in a molten liquid state, where high-temperature gases expand and react in the form of bubble clouds within the liquid explosive;this process is distinctly different from the dynamic crack propagation process observed in the case of solid explosives. In this study, a control model for the reaction evolution of burning-bubble clouds was established to describe the reaction process and quantify the reaction violence of DNAN-based melt-cast explosives, considering the size distribution and activation mechanism of the burning-bubble clouds. The feasibility of the model was verified through experimental results. The results revealed that under geometrically similar conditions, with identical confinement strength and aspect ratio, larger charge structures led to extended initial gas flow and surface burning processes, resulting in greater reaction equivalence and violence at the casing fracture. Under constant charge volume and size, a stronger casing confinement accelerated self-enhanced burning, increasing the internal pressure, reaction degree, and reaction violence. Under a constant casing thickness and radius, higher aspect ratios led to a greater reaction violence at the casing fracture. Moreover, under a constant charge volume and casing thickness, higher aspect ratios resulted in a higher internal pressure, increased reaction degree, and greater reaction violence at the casing fracture. Further, larger ullage volumes extended the reaction evolution time and increased the reaction violence under constant casing dimensions. Through a matching design of the opening threshold of the pressure relief holes and the relief structure area, a stable burning reaction could be maintained until completion, thereby achieving a control of the reaction violen

关键词： Flow of gases

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Tuning thermal stability and mechanical sensitivity of polynitro compounds via integrating energetic ionic salts

Energetic Materials Frontiers

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Energetic Materials Frontiers 2025年第1期6卷 59-66页

作者： Xu, Mei-Qi Dong, Wen-Shuai Lu, Zu-Jia Li, Cong Zhang, Chao Zhao, Bin-Shan Li, Deng-Ke Tian, Feng-Yuan Yu, Qi-Yao Zhang, Jian-Guo State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing100081 China

Polynitro energetic compounds are a class of oxidant-rich energetic materials, playing a significant role in the field of solid propellants. Generally, an increase in the number of nitro groups present in these compounds is associated with a decrease in thermal stability, while simultaneously resulting in an enhancement of mechanical sensitivity. The incorporation of nitrogen-containing organic bases in the synthesis of polynitro energetic ionic salts facilitates a more uniform distribution of charge and promotes the formation of both intramolecular and intermolecular hydrogen bonds. This strategy effectively enhances the thermal stability of HEDMs while decreasing their mechanical sensitivity. In this study, two polynitro nitrogen-containing organic salts based on the triazole framework, namely ammonium salt (4) and hydroxylamine salt (5), were designed and synthesized. Comprehensive characterization revealed that both 4 and 5 exhibited excellent detonation performance (D: 8220–8959 m⋅s−1), good thermal stability (Td: 154–175°C), and low mechanical sensitivity (IS: 30–32 J;FS: 240–288 N). Therefore, nitrogen-containing organic salts enhance the overall performance of polynitro energetic compounds, offering significant advantages in terms of safety and application potential. © 2025 The Authors

关键词： Solid propellants

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Low sintering shrinkage porous ceramics: Principles, progress, and perspectives

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Journal of Advanced Ceramics 2025年第2期14卷 1-36页

作者： Jie Xu Yueqi Shao Xiaoying Feng Xiaoyan Zhang Hao Li Jinlong Yang Feng Gao State Key Laboratory of Solidification Processing MIIT Key Laboratory of Radiation Detection Materials and DevicesSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Porous ceramics are lightweight materials with diverse pore structures and are widely applied in areas such as thermal insulation, sound absorption, filtration, catalysis, and energy storage. However, excessive shrinkage during the sintering process of porous ceramics leads to cracking and deterioration, posing significant challenges for achieving complex shapes. Despite its importance, the field of low sintering shrinkage porous ceramics has not received sufficient attention. This review systematically discusses the principles and progress in the development of low sintering shrinkage porous ceramics. First, we introduce the characteristics of various preparation methods, including partial sintering, particle-stabilized foaming, gel-casting, foam-gelcasting, and additive manufacturing (AM). We then explain three primary principles of low sintering shrinkage from the perspectives of the volume effect and mass transfer processes. This review focuses on the properties and applications of typical low sintering shrinkage ceramics such as mullite and alumina, particularly their mechanical properties and thermal conductivity as thermal insulation and ceramic cores. Finally, we summarize the current state and present future perspectives on low sintering shrinkage porous ceramics.

关键词： porous ceramics low sintering shrinkage volume expansion mass transfer process pore structure properties

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Aerodynamic Optimization and Flow Mechanism for a Compressor Cascade at Low Reynolds Number

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Journal of thermal science 2025年第1期34卷 92-109页

作者： LI Lin ZHANG Jianshe CHEN Caiyan TAN Wei ZHANG Yanfeng Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing 100190China

Low-Reynolds-number effect is an important factor affecting the performance of compressors and other main components of high-altitude long-endurance unmanned aerial *** improve the flow condition and reduce flow loss under the condition of high altitude and low Reynolds number(Re),this paper proposes an optimization process based on a surrogate model,which combines the class-shape transformation method(CST),the Latin hypercube sampling(LHS)method,the light gradient-boosting machine algorithm(LightGBM),and a genetic algorithm(GA)to optimize a high-subsonic compressor *** surrogate model is verified to be accurate and can be used in the optimization *** accuracy of the GA is higher than the other algorithms under common test *** optimization results are verified by numerical simulation,and the flow differences before and after optimization are compared,especially the flow within the boundary *** changing the blade shape,the optimization process adjusts the loading distribution to delay the transition of the optimized blade on the suction surface,which changes the turbulent reattachment in the laminar separation bubble(LSB)into laminar ***,the mixing loss induced by the turbulent reattachment of the LSB and the wake loss of turbulent separation at the trailing edge are significantly reduced,and the performance of the compressor profile is finally *** addition,turbulent separation of the optimized profile is delayed reducing the range of the wake region on the suction *** this optimization process,the reduction of total pressure loss coefficient at Re of 2.5×10^(5),3.5×10^(5),and 4.5×10^(5) are 16.32%,20.76%,and 22.16%,respectively.

关键词： low Reynolds numbers compressor optimization boundary layer transition

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Effect of Ti Additions on Mechanical and Thermodynamic Properties of W-Ti Alloys: A First-principles Study

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Journal of Wuhan University of technology(Materials science) 2025年第1期40卷 246-257页

作者： ZHANG Jian NIE Wei HUANG Jin ZHU Ke LIU Ruxia ZHANG Ruizhi LUO Guoqiang SHEN Qiang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Institute for Carbon Neutrality University of Science and Technology BeijingBeijing 100083China

The mechanical and thermodynamic properties of W-Ti alloys(including W_(15)Ti_(1),W_(14)Ti_(2),W_(12)Ti_(4) and W_(8)Ti_(8) alloys)were investigated by the first-principles approach based on density functional *** results indicate that W-Ti alloys except W_(8)Ti_(8) are thermodynamically *** modulus and hardness of W-Ti alloys are smaller than those of pure tungsten and gradually decrease with increasing Ti ***,their B/G ratios and Poisson's ratios exceed those of pure tungsten,suggesting that the introduction of Ti decreases the mechanical strength while enhancing the ductility of W-Ti *** thermal expansion coefficients for W-Ti alloys all surpass those of pure tungsten,indicating that the introduction of titanium exacerbates the thermal expansion behavior of W-Ti ***,elevated pressure has the capacity to suppress the thermal expansion tendencies in titanium-doped tungsten *** study offers theoretical insights for the design of nuclear materials by exploring the mechanical and thermodynamic properties of W-Ti alloys.

关键词： first-principles mechanical properties thermodynamic properties tungsten-titanium alloys

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Study on sulfur resistance of MnO2/Beta zeolite in toluene catalytic combustion: The effect of increased acidity on catalytic performance

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Chinese Journal of Chemical Engineering 2025年第2期78卷 187-195页

作者： Zhuo Wang Zetao Jin Hanqi Ning Baishun Jiang Kaiyuan Xie Shufeng Zuo Qiuyan Wang Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process College of Chemistry and Chemical Engineering Shaoxing University College of Materials Science and Engineering Beijing University of Technology State Key Laboratory of Elemento-Organic Chemistry Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) College of Chemistry Nankai University

Sulfur dioxide(SO2) frequently coexist with volatile organic compounds(VOCs) in exhaust gas. The competitive adsorption of SO2and VOCs can adversely affect the efficiency of catalytic combustion,leading to catalyst poisoning and irreversible loss of activity. To investigate the impact of sulfur poisoning on the catalysts, we prepared the Mn O2/Beta zeolite, and a corresponding series of sulfur-poisoned catalysts through in-situ thermal decomposition of(NH4)2SO4. The decrease in toluene catalytic activity of poisoned Mn O2/Beta zeolite primarily results from the conversion of the active species Mn O2to Mn SO4. However, the crystal structure and the porous structure of Mn O2/Beta zeolite were stable, and original structure was still maintained when 1.6%(mass) sulfur species were introduced. Furthermore,the extra-framework Al of Beta zeolite could capture sulfur species to generate Al2(SO4)3, thereby reducing sulfur species from reacting with Mn4+active sites. The combination of sulfur and Beta zeolite was found to directly produce new strong-acid sites, thus effectively compensating for the effect of reduced Mn4+active species on the catalytic activity.

关键词： (NH4)2SO4 Beta zeolite In-situ thermal decomposition Sulfur-resistant mechanism VOCs catalytic oxidation

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Development of a versatile and high-loading capacity yeast surface assembly system via SpyC/SpyT conjugation

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Process Biochemistry 2025年 155卷 13-22页

作者： Xu, Ke Liu, Hailin Du, Chao Zhang, Faying Wang, Wenya Zhang, Guimin State Key Laboratory of Green Biomanufacturing College of Life Science and Technology Beijing University of Chemical Technology Beijing100029 China State Key Laboratory of Biocatalysis and Enzyme Engineering School of Life Sciences Hubei University Wuhan430062 China

The yeast surface display (YSD) system for enzyme immobilization has a wide range of applications and is of great value in various studies. However, despite the many advantages of the YSD system, the amount of proteins it can display is limited, which restricts its potential applications. To enhance the applicability of the YSD system, we introduced a highly efficient and stable conjugation tool (SpyCatcher-SpyTag (SpyC-SpyT)) into the YSD system and developed a Saccharomyces cerevisiae surface assembly (SSA) system with high loading capacity. The SpyC-SpyT can spontaneously form molecular isopeptide bonds, and the target proteins can be assembled in the SSA system within 5 min. By increasing the copy of SpyC and integrating the expression fragment into the rDNA region, we successfully screened a genetically stable and high-copy strain that could assemble ∼7.8 × 106 SpyT-eGFP molecular count/cell. The organophosphate hydrolase immobilized by the SSA system not only has the similar enzyme activity as the free enzyme, but also has improved thermal stability and enhanced tolerance to acidic and alkaline environments. Further, we found that the immobilized enzyme still retained 77.7 % of its enzyme activity after 6 cycles. In conclusion, we successfully constructed a novel, efficient and stable SSA system for the development of the YSD system. © 2025 Elsevier Ltd

关键词： Enzyme immobilization

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Enhancing the photocatalytic efficiency by the molecular modification effect derived from pollutant adsorption on highly crystalline BiOBr

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Journal of Environmental sciences 2025年第2期148卷 263-273页

作者： Yang Jin Tongyin Liu Yanpeng Mao Fan Li Chun Hu National Engineering Laboratory for Reducing Emissions from Coal Combustion Engineering Research Center of Environmental Thermal Technology of Ministry of EducationShandong Key Laboratory of Energy Carbon Reduction and Resource UtilizationSchool of Energy and Power EngineeringShandong UniversityJinan 250061China Beijing Enterprises Water Group<China>Investment Limited Beijing 100102China Institute of Environmental Research at Greater Bay Key Laboratory for Water Quality and Conservation of the Pearl River DeltaMinistry of EducationGuangzhou UniversityGuangzhou 510006China Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

The adsorption of pollutants can not only promote the direct surface reaction,but also modify the catalyst itself to improve its photoelectric characteristics,which is rarely studied for water treatment with inorganic photocatalyst.A highly crystalline BiOBr(c-BiOBr)was synthesized by a two-step preparation *** to the calcination,the highly crystalline enhanced the interface interaction between pollutant and *** complex of organic pollutant and[Bi_(2)O_(2)]^(2+)could promote the active electron transfer from the adsorbed pollutant to c-BiOBr for the direct pollutant degradation by holes(h^(+)).Moreover,the pollutant adsorption actually modified c-BiOBr and promoted more unpaired electrons,which would coupling with the photoexcitation to promote generate more O_(2)^(•-).The molecular modification effect derived from pollutant adsorption significantly improved the removal of *** work strongly deepens the understanding of the molecularmodification effect from the pollutant adsorption and develops a novel and efficient approach for water treatment.

关键词： Highly crystalline BiOBr Pollutant adsorption Molecular modification Photocatalysis Water treatment

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