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SSRN 2023年

作者： Ren, Jiyun Li, Yuhang Jin, Xiaoling Huang, Xiaole Li, Yang Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

Oxygen-steam gasification of biomass is a promising technology because of its ability to improve syngas quality and reduce energy consumption. In this study, a fixed-bed reactor is employed to assess the effects of inherent alkali and alkaline earth metals (AAEMs) on the catalytic gasification of candlenut wood with large particle size under oxygen-stream atmosphere. The results show that the acid-washing would remarkably remove the inherent AAEMs in biomass, which is affected by the grain direction. In terms of the gasified chars derived from acid-washed biomass, AAEMs content gradually decreases along the end surface and radial direction, which could also be observed from the 3D reconstruction of X-ray CT images. In all biomass samples and gasified chars, micropores (0-10 μm) dominate and are distributed along the grain direction. In general, pores of 20-30 μm and above 30 μm comprise a minor proportion. Inherent AAEMs facilitate an augmentation in char yield as well as BET and total pore volume of gasified char. AAEMs and grain direction have a slight effect on functional groups of gasified chars. The tar component is remarkably affected by the grain direction. Acid-washing pretreatment augments the content and organic species of M2-M4 compounds (containing 2-4 benzene rings) in the tar. It also leads to a decrement in concentrations of H2, CH4, and CO2 by 14.49% and 13.35%, 0.51% and 0.89%, 2.32% and 1.37% in syngas for two-grain direction, respectively. But it raises the CO concentration by 17.1% and 15.18%, resulting in a reduction of 4.09% and 1.53% in syngas calorific value. A decrement in the volume fraction of CnHx induced from AAEMs is significantly affected by the grain direction. © 2023, The Authors. All rights reserved.

关键词： Biomass

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Uncertainty and Sensitivity Analysis of Containment Aerosol Removal Under Severe Accident

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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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Comparative Analysis on Energy Losses in Hydrogen and Helium Turbo-Expanders for Hydrogen Liquefiers

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SSRN 2022年

作者： Zhou, Kaimiao Chen, Liang Li, Shanfeng Zhao, Kang Zhang, Ze Chen, Shuangtao Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Beijing institute of Aerospace Testing Technology Beijing100074 China

The helium Brayton cycle and the hydrogen Claude cycle are the baseline processes for large-scale hydrogen liquefaction. Helium and hydrogen turbo-expanders are the crucial components, respectively, determining the system efficiency and reliability. In this paper, a comparative analysis is performed on the energy losses in helium and hydrogen turbo-expanders for hydrogen liquefaction systems. Similarity analysis is carried out to set the baseline design of helium and hydrogen turbo-expanders. Mean-line method is employed in the design, and losses in nozzle and impeller are determined. CFD simulations are performed to illustrate the internal flow field and loss mechanisms in helium and hydrogen turbo-expanders. The CFD predictions of isotropic efficiency agree well with that by the loss models. The results show that the passage loss in the impeller is the dominant loss for cryogenic hydrogen and helium turbo-expanders. Due to the higher sound speed and lower viscosity, the hydrogen turbo-expander has smaller nozzle loss and incidence loss compared with the helium turbo-expander, but the tip clearance loss and residual velocity loss in the hydrogen expander are larger. © 2022, The Authors. All rights reserved.

关键词： Helium

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Propagation and Burning Velocity of Iron-Methane-Oxygen-Nitrogen Turbulent Expanding Flames

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SSRN 2023年

作者： Cai, Xiao Su, Limin Su, Shouguo Wang, Jinhua Alden, Marcus Li, Zhongshan Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Division of Combustion Physics Lund University P.O. Box 118 LundS221 00 Sweden

The propagation and burning velocity of iron-methane-oxygen-nitrogen turbulent expanding flames were experimentally studied by employing a newly optimized spark-ignition, fan-stirred combustion chamber, in which micron-sized iron particles can be dispersed homogeneously. Fine iron particles with averaged diameter of 1.9 μm was used in the present study. The flame trajectory of iron-methane mixture at different turbulence intensities and iron concentrations was recorded using a high-speed camera. It was found that the flame propagation speed increases as iron-methane turbulent flame expands. The acceleration process is mainly caused by the extension of flame surface dissipation spectrum by increasing the largest flame scales (flame radius). The turbulent burning velocity, ST increases significantly with the turbulence intensity, which is well known feature in gaseous flames. However, the iron concentration does not have an obvious effect on the ST, which is unique to iron flame in turbulence environment. Because the turbulent flame propagation is dominated by turbulent heat transfer, which is characterized by turbulence intensity. In addition, the formation of iron flame front is controlled by the couple effects of iron concentration and turbulence intensity in turbulent environment. Furthermore, the laminar burning velocity, SL was accurately determined using a nonlinear extraction method. A correlation of turbulent burning velocity was obtained based on the experimental iron-methane data. The measured ST and its correlation would be used to develop practical iron burners and to validate turbulent combustion models of iron flames. © 2023, The Authors. All rights reserved.

关键词： Iron

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flow and Thermal Analysis of the Transition Scheme between Micro-Channel and Micro-Jet Cooling Solution

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SSRN 2022年

作者： Guo, Yuming Fan, Liang-Liang Zhao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Xi'an Jiaotong University Xi'An China

With the rapid development of high-power electronics, the thermal management of these emerging devices is challenging due to the danger of ultra high heat flux and uneven temperature distribution. In this perspective, as promising cooling technologies, micro-channel and micro-jet cooling designs have been extensively investigated. In the past decade, certain heat-dissipation technologies based on micro-channel and micro-jet cooling have utilized geometrically identical heat sinks;however, their corresponding flow and thermal characteristics are dissimilar including micro-channel cooling technologies often have large temperature gradients as well as high heat transfer coefficients, while microjet technologies are more advantageous in terms of temperature distribution uniformity but larger pressure drop penalty. To characterize the enhanced heat-transfer mechanism driving this dissimilitude, a transition scheme between micro-channel and micro-jet was designed, featuring a gap on the channel fins top to provide extra flow area, and investigated experimentally and numerically. By controlling the volumetric flow ratio of the channel and jet, the flow and thermal characteristics of the transition scheme could be interchangeably transformed between the micro-channel and micro-jet. Moreover, we investigated the effect of the vortex generated by the jet impingement on channel bottom and fins top, an important factor causing the distinctions between the two schemes. The results revealed that the vortex in the stagnation zone enhanced the local heat-transfer coefficient corresponding to the channel bottom and promoted temperature uniformity;however, it caused the thermal boundary layer on the fins top to thicken. Although the vortex was favorable for the forced convection in the acceleration zone, the vortex intersections formed by adjacent jets introduced a greater pressure-drop penalty and flow blockage, which were not conducive to enhancing the heat transfer. Subsequently,

关键词： Vortex flow

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Numerical Study on Benchmark Analysis of NACIE-UP Facility with Uniform and Non-Uniform Power Distribution

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SSRN 2024年

作者： Li, Haoyang Zhang, Dalin Zhou, Lei Deng, Jian Tian, Wenxi Su, Guanghui Qiu, Suizheng 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 Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The NACIE-UP facility is located at the ENEA Brasimone Research Centre and is designed to investigate the thermo-hydraulic properties of LBE within a wire-spaced assembly under uniform and non-uniform power distribution conditions. In this study, the thermo-hydraulic characteristics of FPS are analyzed. ANSYS Fluent solver is applied with the COUPLE algorithm of RANS [[EQUATION]] model. Cheng&Tak correlation and computational conditions are implanted into Fluent in the form of UDFs. The results show that the RMSEs of ADP10SS1 and ADP10SS2 are 2.52 K and 3.69 K, 7.05 K and 8.48 K for ADP06SS1 and ADP06SS2, respectively, which indicate that the adopted models have good prediction ability for the temperature of the experimental conditions. Meanwhile, the heat transfer characteristics are investigated and compared with the correlations of Ushakov, Mikityuk, Kazimi and Carelli. Above all, this study provides quantitative and qualitative analysis for verification and validation of CFD/STH code and stand-alone CFD simulation. © 2024, The Authors. All rights reserved.

关键词： Heat transfer

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Numerical Simulation for Non-Uniform Ptco Catalyst Degradation Under Constant Voltage Condition and its Impact on Pemfc Performance

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SSRN 2023年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Hu, Chengzhi Gao, Linsong Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China

PtCo alloys are commonly utilized as catalysts in proton exchange membrane fuel cell (PEMFC) to reduce Pt loading and to achieve higher oxygen reduction reaction (ORR) activity. However, long-time operation can result in a reduction in electrochemical surface area (ECSA) in PEMFC. Meanwhile, the dissolved Co2+ may also contribute to additional local oxygen transport resistance. In this study, catalyst aging model and Co2+ transport and its effect on oxygen transport model have been integrated with the 3D single phase PEMFC performance model to develop a long-term performance model for investigating the impact of non-uniform catalyst degradation and Co2+ contamination on PEMFC performance during constant voltage operation. The results show that Co2+ contamination causes additional mass transfer losses and reduces the peak power of PEMFC. And it is found that the non-uniform degradation of catalyst and Co2+ contamination eventually affects the current density distribution in aged PEMFCs. In addition, the model is also applied to study a 50 cm2 PEMFC under long time constant voltage operation. The predicted ECSA loss is 73.1% and 62.0%, and output power reduction is 55.9% and 43.0% after 80,000 hours at a constant voltage of 0.75 V and 0.65 V, respectively. © 2023, The Authors. All rights reserved.

关键词： Numerical models

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Navigating the Dual Pathways of Ion Removal in flow-Electrode Capacitive Deionization: Capacitive Trapping vs. Electrodialytic Migration

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SSRN 2025年

作者： Gu, Haibo Hou, Chengsi Mao, Yunfeng Wu, Deli School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science & Engineering Tongji University Shanghai200092 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092 China

By introducing flowing electrodes, FCDI enables desalination through dual mechanisms of electrodialytic and capacitive effects. Clarifying their distinct roles is essential to advance tailored system design and performance enhancement. This work elucidates the antagonistic interplay between capacitive trapping and electrodialytic migration in flow-electrode capacitive deionization (FCDI) through both electrochemical characterization and multiphysics modeling. Experimental analyses reveal that elevated flow rates enhance electrodialytic migration but impair capacitive adsorption. Multivariate parametric studies demonstrate that capacitive dominance prevails at high current densities and low electrolyte concentrations, whereas electrodialytic effects peak under high electrolyte concentration and moderate flow rates. The balance between the effects of electrodialysis (ED) and capacitive deionization (CDI) is greatly impacted by convective mass transfer, which is caused by the electrode flow rate. While higher solid weight percentages in the flow electrode improve the CDI effect by increasing the number of active sites for salt adsorption, increased electrode flow rates maximize the ED effect by encouraging ion transport in the electrolyte. In short words, strategies to promote free ions dispersing in the electrolyte would enhance the electrodialytic contribution, whereas the concentration polarization would benefit the capacitive contribution. This work opens the door for the exploration of upgrading FCDI architectures and optimizing operation parameters while providing insights into the intricate interactions within the system. © 2025, The Authors. All rights reserved.

关键词： Desalination

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Thermal management performance and optimization of a hybrid system integrating liquid cooling and fin-enhanced phase change material for large-capacity energy storage battery pack

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Energy Conversion and Management 2025年 336卷

作者： Lin, Xiang-Wei Zhou, Zhi-Fu Liu, Maochang Chen, Bin Lu, You-Jun Jing, Deng-Wei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Battery energy storage systems become increasingly important to address the intermittency of renewable energies, but their widespread adoption is still hindered by thermal concerns. However, a single thermal management strategy cannot ensure the overall performance of energy storage battery systems. In this study, a hybrid strategy combining topological fin structure, phase change material, and active liquid cooling is established for 280 Ah lithium-ion battery pack. A fluidic-thermal-phase change coupled model is built and verified experimentally. Meanwhile, a novel comprehensive evaluation parameter is defined to feature the overall performance of thermal management system. Based on this, comparative investigations are conducted to assess the efficiency of three cooling strategies. Despite additional weight caused by hybrid design, topological fin structure not only constructs the thermal conduction in phase change material but also dissipates the accumulated heat by connecting cold plate. Additionally, the impacts of fin fraction, thickness of phase change material, and inlet velocity are systematically explored using single-factor analysis. Furthermore, a surrogate-based model is utilized to reveal the interactions between design parameters and system performance, while accomplishing a global optimization. In contrast to original design, comprehensive evaluation parameter is reduced by 0.218, 0.273, 0.256, and 0.2 for discharge rates of 0.25, 0.5, 0.75, and 1C, respectively. © 2025 Elsevier Ltd

关键词： Battery storage

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Study on the Flame Structure and flow Field of Hydrogen-Enriched Combustion in Array Micro-Tube

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SSRN 2024年

作者： Tian, Liang Feng, Wenbin Han, Xiao Liu, Yuzhi Liu, Hongfang Cai, Xiao School of Energy and Environmental Engineering Hebei University of Technology Tianjin300401 China National Key Laboratory of Science and Technology on Aero-Engine Aero thermodynamics Research Institute of Aero-Engine Collaborative Innovation Center for Advanced Aero-Engine Beihang University Beijing100191 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

Addressing climate change and reducing greenhouse gas emissions are critical priorities. Utilizing hydrogen-rich methane or pure hydrogen as fuels within gas turbines, facilitated by array micro-tube premixed combustion technology, is anticipated to markedly accelerate the decarbonization process of the energy sector. In this study, the flame structure of the array micro-tube premixed burner under various fuel compositions was examined using OH-Planar Laser-Induced Fluorescence (OH-PLIF) and Particle Image Velocimetry (PIV) measurement techniques. The effects of the equivalence ratio (φ) and the hydrogen power ratio (HPR) on the characteristics of the flame front, including its curvature, density, volume, and the associated flow field properties, were discussed. As φ and HPR increase, the wrinkled structure of the flame front is significantly enhanced, with a more pronounced effect on smaller scales. This enhancement leads to the separation of the unburned pockets from the main flame. Concurrently, both the flame length and flame area decrease with the augmentation of φ and HPR, indicating a more concentrated combustion process and increased combustion intensity under hydrogen-enriched and pure hydrogen conditions. The study also observed a slight increase in both the negative and positive curvatures of the flame front, with a more notable increase in negative curvature. The increased negative curvature results in an elevated degree of wrinkling and a higher value of Σ (flame surface density), reaching a maximum of 0.876 mm-1 under the conditions where φ is 0.8 and (mean progress variable) is 0.5, resulting in the smallest observed flame volume of 100.6 mm3. Upon coupling the flame with the flow field, it was discovered that the exit flow field of the array micro-tube exhibits symmetry and a characteristic conical flame shape. The burning velocity of the side flame brushes increases, and the velocity peak shifts upstream. The above findings confirms that the additio

关键词： flow fields

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