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Performance and Sizes of sCO_(2)Multistage Axial Compressors at Various power Capacities

Journal of Thermal Science 2025年第2期34卷 352-373页

作者： WANG Tianze XU Jinliang ZHENG Haonan QI Jianhui Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing100026China Key Laboratory of Power Station Energy Transfer Conversion and System(North China Electric Power University) Ministry of EducationBeijing102206China School of Energy and Power Engineering Shandong UniversityJi’nan250061China

The supercritical carbon dioxide(sCO_(2))cycle can be powered by traditional as well as clean *** help users obtain more accurate results than the literatures with pre-set compressor efficiency,we proposed a complete model to establish a link between the performance,sizes of compressors and parameters such as power W_(C),inlet temperature T_(in),inlet pressure P_(in)and pressure ratioε.Characteristic sizes of compressors l_(c),profile loss Y_(p)and clearance loss Ycl are all proportional to powers of W_(C)with powers of 0.5,-0.075 and-0.5 to 0 respectively;the scaling laws are constant in the range of capacities from 20 MW to 200 *** compressor isentropic efficiencyη_(tt)grows as the W_(C)increases,and the curves become *** efficiency improves over the full power range when the speed is changed from standard speed to the optimal speed;theη_(tt)curves turn soft as the n *** the P_(in)and T_(in)approach the critical point,theη_(tt)*** efficiency follows a parabolic curve as theεincreases,this parabolic distribution results from the tradeoff between the change in losses and the pressure distribution of ***η_(tt)versus P_(in),T_(in)andεrelations are similar at various capacities because of insignificant changes in the distribution of *** efficiency maps facilitate the estimation of system performance,while scaling law for irreversible losses and characteristic lengths,along with constant criterion analyses,aid in comprehending the characteristics of compressors across various capacities.

关键词： sCO_(2)cycle compressor efficiency irreversible losses scaling laws

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Performance comparison investigation on different pulse tube position heat pumps with power recovery displacer

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International Journal of Refrigeration 2025年 176卷 1-16页

作者： Zhu, Shenglin Chen, Xi Zhu, Yifan Qi, Yingxia School of Energy and Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China

Spacecraft waste heat is dissipated into space primarily by radiation. To improve the heat dissipation efficiency of spacecraft radiators in high-temperature environments and reduce heat wastage in spaceflight thermal control systems, thermoacoustic heat pumps (TAHP) are considered a viable method for increasing radiator cooling temperatures and recovering waste heat. In this study, one-dimensional simulations are used to optimize the geometrical parameters of the 100-watt work recovery thermoacoustic heat pump (WRTAHP) for various pulse tube positions. The performances of the two systems are compared at a cold-end temperature of 293 K and a hot-end temperature of 353 K. The results reveal that a heating capacity of 256 W with a relative Carnot efficiency of 35.01 % is achieved for the pulse tube front-type thermoacoustic heat pump (FTTAHP), whereas the pulse tube back-type thermoacoustic heat pump (BTTAHP) obtains a heating capacity of 225 W with a relative Carnot efficiency of 30.59 %. As the cold-end temperature decreases, the coefficient of performance is reduced for FTTAHP, while the performance of BTTAHP shows a substantial improvement. At a cold end temperature of 233 K and a hot-cold end temperature difference of 60 K, a heating capacity of 268 W with a relative Carnot efficiency of 50.57 % is achieved for BTTAHP. Furthermore, the heating capacity of the BTTAHP is not significantly increased by adopting the active phase adjustment structure. In summary, the FTTAHP is suitable for spacecraft radiator applications and avoids high temperatures affecting compressor operation, whereas the BTTAHP is better suited for low-temperature heating. © 2025 Elsevier Ltd and IIR

关键词： Waste heat utilization

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Concurrently Boosting Activity and Stability of Oxygen Reduction Reaction Catalysts via Judiciously Crafting Fe-Mn Dual Atoms for Fuel Cells

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Nano-Micro Letters 2025年第4期17卷 275-289页

作者： Lei Zhang Yuchen Dong Lubing Li Yuchuan Shi Yan Zhang Liting Wei Chung-Li Dong Zhiqun Lin Jinzhan Su International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China Department of Physics Tamkang UniversityNew Taipei CityTaiwan 25137People’s Republic of China Department of Chemical and Biomolecular Engineering National University of SingaporeEngineering Drive 4Singapore 117585Singapore

The ability to unlock the interplay between the activity and stability of oxygen reduction reaction(ORR)represents an important endeavor toward creating robust ORR catalysts for efficient fuel ***,we report an effective strategy to concurrent enhance the activity and stability of ORR catalysts via constructing atomically dispersed Fe-Mn dualmetal sites on N-doped carbon(denoted(FeMn-DA)-N-C)for both anion-exchange membrane fuel cells(AEMFC)and proton exchange membrane fuel cells(PEMFC).The(FeMn-DA)-N-C catalysts possess ample dual-metal atoms consisting of adjacent Fe-N_(4)and Mn-N_(4)sites on the carbon surface,yielded via a facile doping-adsorption-pyrolysis *** introduction of Mn carries several advantageous attributes:increasing the number of active sites,effectively anchoring Fe due to effective electron transfer to Mn(revealed by X-ray absorption spectroscopy and density-functional theory(DFT),thus preventing the aggregation of Fe),and effectively circumventing the occurrence of Fenton reaction,thus reducing the consumption of ***(FeMn-DA)-N-C catalysts showcase half-wave potentials of 0.92 and 0.82 V in 0.1 M KOH and 0.1 M HClO_(4),respectively,as well as outstanding *** manifested by DFT calculations,the introduction of Mn affects the electronic structure of Fe,down-shifts the d-band Fe active center,accelerates the desorption of OH groups,and creates higher limiting *** AEMFC and PEMFC with(FeMn-DA)-N-C as the cathode catalyst display high power densities of 1060 and 746 mW cm^(-2),respectively,underscoring their promising potential for practical *** study highlights the robustness of designing Fe-containing dual-atom ORR catalysts to promote both activity and stability for energy conversion and storage materials and devices.

关键词： Doping-adsorption-pyrolysis Dual-atom catalysts Oxygen reduction reaction Fuel cells

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Multi-objective optimization of 200 kW air centripetal turbine based on artificial neural networks

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International Journal of Advanced Nuclear Reactor Design and Technology 2025年第2期7卷 70-80页

作者： Wang, Zideng Zhang, Yan Leng, Yuyang Lai, Jiabao Wang, Zhenzhen Chen, Weixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The air-Brayton cycle has the characteristics of safety and high efficiency, which can be used as an energy conversion system for mobile small reactors. The air turbine is one of the key components in the cycle system, and improving its performance is of great significance. In this paper, an artificial neural network model combined with a genetic algorithm was used to optimize the rotor of an air centrifugal turbine with axial thrust and efficiency as the objective. The results show that the artificial neural network model can fit the CFD numerical simulation results well, with a coefficient of determination larger than 0.97. Then, after optimizing the artificial neural network model with a genetic algorithm, the total -total efficiency of the air centrifugal turbine was improved by 1.479 %, while the axial thrust was reduced by 1.07 %. © 2025 Xi'an Jiaotong University

关键词： Genetic algorithms

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Effect of H2/CO ratio on non-isothermal reduction behavior and kinetics of vanadium titanomagnetite

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International Journal of Hydrogen Energy 2025年 139卷 69-79页

作者： Shi, Jian Xu, Qiang Lu, Xuyang Cao, Zeshui Kang, Haopeng Chen, Bin Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Hydrogen-based direct reduction of vanadium titanomagnetite is crucial for developing clean and efficient hydrogen metallurgy technology, while existing studies lack systematic research on the impact of H2/CO ratios on the reduction of vanadium titanomagnetite under non-isothermal conditions. This study examines the influence of varying H2/CO ratios on the non-isothermal reduction behavior and kinetics of vanadium titanomagnetite through thermogravimetric analysis (TGA). The results of thermogravimetric experiments show that raising the H2 ratio can significantly lower the initial reduction temperature and accelerate the reduction rate. When H2/(H2+CO) rises from 0 to 1, the initial reduction temperature can be lowered by around 150 °C at a heating rate of 10 °C/min. As the heating rate decreases, the reduction curve shifts to the low-temperature region, and the reduction reaction becomes easier to proceed. The vanadium titanomagnetite reduction activation energy was calculated using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) model-free kinetic methods, and the activation energy of vanadium titanomagnetite reduction under pure CO atmosphere (H2/(H2 + CO) = 0) was the highest (120.74 kJ/mol by FWO and 107.82 kJ/mol by KAS). As the H2/(H2+CO) ratio increases, the activation energy continuously decreases, effectively reducing the reduction energy barrier of vanadium titanomagnetite. In contrast to an environment of pure CO, the activation energy for the reduction of vanadium titanomagnetite was reduced by 25.47 % (FWO method) or 28.73 % (KAS method) in a pure H2 atmosphere (H2/(H2 + CO) = 1), indicating that an elevated H2 ratio significantly enhanced the reduction of vanadium titanomagnetite. XRD analysis showed that, after the non-isothermal reduction, unreduced iron oxide was still present within the vanadium titanomagnetite under a pure CO atmosphere, while the final reduction product was mainly metallic iron under different H2/CO ratios. Increas

关键词： Activation energy

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A multi-physics model-based approach for macro-structured surface design to enhance heat transfer in R410A flash spray cooling systems

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International Journal of Heat and Mass Transfer 2025年 247卷

作者： Ye, Ying-Dong Lin, Xiang-Wei Zhou, Zhi-Fu Liu, Maochang Chen, Bin Lu, Youjun Jing, Dengwei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Refrigerant flash spray cooling, which offers high heat flux dissipation at low temperatures, holds significant potential for thermal management of high-power electronic devices. While surface structure design can further amplify heat transfer performance, the lack of systematic methodologies to address the complexities of spray cooling has hindered progress. This study establishes a multi-physics computational framework that couples two-phase flash spray dynamics, liquid film heat transfer, and solid heat conduction to systematically optimize macro-structured surfaces. After validating the model against experimental data, the effects of surface geometry (flat, square, straight and pyramid fins) and dimensional parameters on cooling performance were analyzed. The pyramid structure demonstrated superior performance, achieving a 9 K reduction in surface temperature and a 70 % increase in effective heat transfer coefficient compared to the flat surface. Quantitative analysis revealed that optimal macro-structured design hinges on maximizing effective heat transfer area while ensuring uniform liquid film distribution via controlled droplet dynamics. Further parametric studies on nine pyramid geometries identified a base length of 1 mm and height-to-edge ratio of 0.7 as the optimal configuration, balancing heat transfer enhancement and manufacturing costs through a newly proposed Composite Heat Transfer Factor (CHTF). This work provides a mechanistic framework for designing enhanced surfaces in spray cooling systems, bridging critical gaps in both theoretical understanding and engineering application. © 2025 Elsevier Ltd

关键词： Film cooling

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Promoting effect of d-band center and in-situ precipitation strategy on sulfur evolution reaction

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Journal of Energy Chemistry 2025年第5期104卷 740-748页

作者： Jun Pu Yun Tan Jiasen Yin Zihan Shen Shoujie Liu Kai Zhang Lei Zhou Yagang Yao Key Laboratory of Functional Molecular Solids Ministry of Education Anhui Provincial Engineering Laboratory for New-Energy Vehicle Battery Energy-Storage Materials College of Chemistry and Materials Science Anhui Normal University National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences Jiangsu Key Laboratory of Artificial Functional Materials Collaborative Innovation Center of Advanced Microstructures Nanjing University State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences School of Materials Science and Engineering Anhui University School of Energy and Power Engineering Jiangsu University Department of Electrical Engineering Eindhoven University of Technology

The slow conversion of polyphase in lithium-sulfur （Li-S） batteries not only intensifies the shuttle effect of lithium polysulfides （LiPSs）,but also causes the continuous accumulation of inactive sulfur species,resulting in rapid capacity attenuation and sluggish dynamic ***,the promoting effect of atomic interface stress on sulfur reaction was investigated via CoFe-CoFe2O4heterogeneous nanosheets with a cavity *** strain force induced by the in-situ precipitation of Co Fe bimetallic alloy in oxide matrix increased the d-band center,which was conducive to the interaction between catalyst and Li *** sulfur cathode based on this two-dimensional （2D） nanosheet design showed an extremely high capacity of 751 mAh g-1at 4 *** with a sulfur loading of 5.55 mg cm-2,its area capacity was still as high as 7.15 mAh ***,the enhanced stability greatly improved the practical potential of Li-S batteries.

关键词： 2D nanosheets D-band center In-situ precipitation Li-S batteries Strain effect

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On the Oxidation Mechanism of n-Dodecane under Pure Oxygen Conditions from Low to High Temperatures

On the Oxidation Mechanism of n-Dodecane under Pure Oxygen C...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Hong, Congjie Zou, Jiabiao Subburaj, Janardhanraj Farooq, Aamir Zhang, Yingjia Thuwal23955 Saudi Arabia State Key Laboratory of Multiphase Flows in Power Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9781624107238

This study investigates the combustion characteristics of n-dodecane under pure oxygen conditions, a critical scenario for rocket propulsion systems. Advanced laser absorption diagnostics were employed to measure the oxidation of key species, including n-dodecane, CO, and H2O, across a wide range of temperatures. The experimental data were used to refine chemical kinetic models by optimizing the rate coefficients of key reactions. The optimized models demonstrated improved predictive accuracy for ignition delay times and species concentration profiles, providing deeper insights into the combustion process. These findings enhance the understanding of n-dodecane combustion and contribute to the development of efficient and environmentally sustainable rocket propulsion technologies. Additionally, the study advances modeling methodologies, offering direct implications for the design of more robust and sustainable rocket engines. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Rockets

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Numerical study of specific C-shaped heat exchanger using porous medium and coarse mesh coupling method

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International Journal of Thermal Sciences 2025年 210卷

作者： He, Shaopeng Wang, Shiqi Wang, Mingjun Tian, W.X. Qiu, S.Z. Su, G.H. State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

Porous medium method is an effective simplified approach for the heat exchanger simulation when the numerous tubes and complex structures bring unacceptable computational resources to full-scale simulation. However, for the specific C-shaped heat exchanger, the tube side resistance and flow distribution characteristics that significantly affects the heat transfer and natural circulation performance cannot be obtained by the traditional porous medium method coupled with the one-dimensional node model for tube side. It is urgent to develop a new coupling method that can not only simplify modeling and calculation, but also obtain tube side high-resolution flow heat transfer characteristics. This study presents a novel calculation method which couples the porous medium mesh and the tube side coarse mesh. The coupling method was then applied to a typical C-shaped passive residual heat removal heat exchanger (PRHR HX), which is significant to the stable operation and the mitigation of accident conditions in the nuclear power plant. The coupling calculation method was validated against the full-scaled simulation and data from scaled-down experiment. The average relative error of heat transfer power is 2.1 % under steady state conditions. Under transient conditions, the average absolute error of the fluid temperature and wall temperature are less than 6 K. Then the 3D thermal-hydraulic characteristics of PRHR HX was studied. Owing to a greater gravitational pressure head, the mass flow rates in the extended tubes surpass those in the shorter tubes by a relative deviation of 27.4 %. The upper horizontal tube's heat exchange capacity constitutes approximately 70 % of the total power, leading to enhanced natural circulation. The outlet temperatures from various tubes tend to equalize. The boiling area gradually extended down along the heat transfer tubes. Our work would present an innovative calculation method to the numerical study and design optimization of the C-shaped heat

关键词： Nuclear power plants

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Thermal mechanical response analysis of the first wall in laser initial confinement fusion reactors

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International Journal of Advanced Nuclear Reactor Design and Technology 2025年第2期7卷 147-155页

作者： Xinze Li Bingqian Zhang Chengcheng Tong Ronghua Chen Dalin Zhang Wenxi Tian Suizheng Qiu 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'an 710049 China

This paper investigates the thermo-mechanical response characteristics of the first wall of a laser initial confinement fusion reactor under periodic transient heat flux loads. The first wall of the reactor experiences extremely high instantaneous heat loads during the target compression process, leading to temperature and thermal stress oscillations, which can cause material fatigue damage. Finite element analysis is employed to model the first wall under various chamber sizes and target energies, and the thermal-mechanical response characteristics of W, W/Cu functional gradient materials, and blanket materials are studied under thermal shock and cyclic loading conditions. The results indicate that W/Cu functional gradient materials can effectively alleviate thermal stresses on the first wall, especially in addressing the stress concentration at the interface. Fatigue life of the first wall is assessed using the Basquin model, and it is found that increasing the chamber size and increasing the target frequency can significantly reduce temperature oscillations and thermal stresses, thus extending the service life of the first wall. This study provides valuable design references for the optimization and design of the first wall in laser initial confinement fusion reactor.

关键词： Laser inertial confinement fusion reactor First wall Heat oscillation Thermal fatigue

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