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SSRN 2024年

作者： Huang, Heng Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lyu, Jizu Hu, Chengzhi Gao, Linsong 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China

The structure and spatial distribution of electrochemical inert phase (EIP) in electrodes are highly heterogeneous, which deteriorates the performance of electrodes under harsh operating conditions such as high-rate or low-temperature. In this work, with the assist of digitally processed X-ray computed tomography (XCT) for charactering images of LiNi0.5Co0.2Mn0.3 electrode, the electrodes with different EIP geometries are reconstructed, and the dependence of electrode performance degradation on EIP is elucidated from a multiscale perspective. Physical structure characterization and 3D microstructure resolved model reveal that, compared to 3D bulk EIP (B-EIP), 2D film EIP (F-EIP) tends to cover active surface of active material (AM), which exacerbates the heterogeneous electrode lithiation reaction. The decrease of AM active surface area makes the state of lithiation (SOL) of particles closely related to their active specific surface area (αa). The temperature sensitivity of electrodes at low temperatures exacerbates the hazard of αa loss, allowing heterogeneous reaction transfer between particles. The Biot number (Bi) evaluates the competing mechanisms between interfacial reactions and bulk diffusion of particles, and the reaction rate at the particle/electrolyte interface is accelerated in high content EIP electrodes, allowing the Li concentration gradient within the particles to be dominated by interfacial reactions. Finally, the electrochemistry and heat generation from particle to electrode level in high area-loaded electrodes are explored, showing that the lithium ion diffusion in the pores controls the interfacial reactions and heat transport behavior. The aggregated high flux reactions and localized hot spots aggravate the heterogeneous degradation and side reactions of the electrode. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Energy and exergy analyses of a novel recirculated regenerative rotary desiccant wheelassisted dehumidification system 33

Energy and exergy analyses of a novel recirculated regenerat...

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33rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2020

作者： Han, Xiaoqu Wu, Wenxiang Chong, Daotong Su, Minqi Zhang, Dan Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an China MOE Key Laboratory of Thermal Fluid Science and Engineering Xi'An Jiaotong University Xi'an China

The indoor air humidity and temperature in the marine cabins could be as high as 80% and 40 °C - 50 °C, respectively, which may cause security risks to crews and devices. The incorporation of solid desiccant wheel for improved dehumidification and air quality control would contribute to energy saving in air conditioning system through waste heat recovery for regeneration. In the present work, a novel recirculated regenerative rotary desiccant wheel-assisted dehumidification system was proposed. The energy and exergy performances of the system under variable working conditions were quantitatively studied based on experimental tests. The dehumidification effectiveness, dehumidification performance coefficient (DCOP), sensible energy ratio and coefficient of performance (COP) were introduced as key energetic indicators. The effects of air bypass ratio (50% - 85%), process air temperature (28 °C - 40 °C), relative humidity of process air (60%RH - 80%RH) and regeneration air temperature (130 °C - 150 °C) on the system performances were obtained. It was found the COP of the system ranged between 0.4 and 1.8, while the exergy efficiency was only 4% - 11%. An optimal bypass ratio existed which was determined 55%-60%. Overall, the energy saving and exergy consumption characteristics of the proposed system at various working conditions were explored to prompt its practical application. © ECOS *** right reserved.

关键词： Waste heat

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Investigation of Droplet Dynamic Behavior in Pemfcs Gas Diffusion Layer and Gas Channel with Micro-Ct and Lattice Boltzmann Method

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SSRN 2024年

作者： Lv, Xuecheng Zhou, Zhifu Wu, Wei-Tao Wei, Lei Gao, Linsong Lyu, Jizu Hu, Chengzhi Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

This study reconstructed the 3D structure for the gas diffusion layer (GDL) of proton exchange membrane fuel cells (PEMFCs) using the micro-CT technique and investigated the dynamic behavior of droplets inside the multi-scale space of GDL and gas channel (GC) using the lattice Boltzmann method (LBM). The prediction model for droplet detachment at the GDL-GC interface was developed. The results indicate that there is a significant difference between the breakage location of the liquid bridge and the trajectory of the liquid droplet after detaching from the GDL-GC interface in the multi-scale space of GC and GDL, compared to the single-scale GC space where GDL is ignored. The increase in gas velocity and internal contact angle of the GDL contribute to reducing the droplet detachment volume and increasing the droplet detachment frequency. At the internal contact angle of 120º-140º, GDL exhibited the most efficient removal of liquid water. A contact angle smaller than this range would hinder the detachment of droplets in the GC, while a contact angle larger than this range would lead to the accumulation of liquid water in the GDL. The surface force generated by the connection of liquid bridges in the analytical model for critical droplet detachment forms an angle with the gas flow direction, with the characteristic length determining this force being the minimum diameter at the necking of the liquid bridge. © 2024, The Authors. All rights reserved.

关键词： Contact angle

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Thermodynamic analysis on a heat-power decoupling system integrated with absorption heat pump

Thermodynamic analysis on a heat-power decoupling system int...

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2019 Canadian Society for Civil engineering Annual Conference, CSCE 2019

作者： Wang, Liyuan Liu, Ming Fu, Yue Liu, Jiping Yan, Junjie MOE Key Laboratory of Thermal Fluid Science Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

ISBN: (纸本)9780791883747

Because of the continuous expanding of the district heating, the heating load of combined heat and power(CHP) plants increases year by year. The minimum power load of CHP plant increases with the heating load due to the heat-power coupling mechanism. Therefore, heat-power decoupling is necessary to improve the operation flexibility for CHP units. Integrating the absorption heat pump(AHP) is an effective method to realize the heat-power decoupling. In this study, a 330MW CHP unit model and AHP model have been developed and validated. The performance of the heat-power decoupling and energy saving performance has been investigated by comparing the thermodynamic performance indicators. Results show that, the proposed system can increase the maximum heating load and decrease the power generation when the primary network return temperature is decreased. When the heating steam extraction is kept constant, with the increase of the primary network return water temperature, the heat generation efficiency and the standard coal consumption rate of heating increases, the coal consumption rate of power generation and the heating efficiency decreases. And the primary network return water temperature increases from 40 °C to 70 °C, the coal consumption rate of power generation decreases by 4.3 g/kWh, and the coal consumption rate of heating increases by 0.67 kg/GJ. Copyright © 2020 ASME.

关键词： Water temperature

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Predicting self-diffusion coefficients of light gases in supercritical carbon dioxide: A molecular dynamics method

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The Journal of Supercritical Fluids 2025年 225卷

作者： Tongjia Zhang Bowei Zhang Jie Zhang Xiaoran Rong Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 PR China

The methanation of CO 2 and supercritical CO 2 (scCO 2 ) fracturing represent effective approaches for CO 2 utilization and greenhouse effect mitigation. In these process, light gases like H 2 , O 2 , CO, CH 4 are commonly involved. However, limited studies have focused on the diffusion behavior of these gases in scCO 2 under high-pressure conditions, as well as a shortage of self-diffusion coefficient data and prediction equations specifically designed for scCO 2 solvents. To address this gap, molecular dynamics (MD) simulations were employed to compute the self-diffusion coefficients of several light gases in scCO 2 across a wide temperature range (313 K–713 K) and at high pressures (75.994 bar, 101.325 bar and 126.656 bar) under infinitely dilute conditions. The effects of temperature, density, viscosity, molecular mass, and solute–solvent interaction energy on the self-diffusion behavior were systematically analyzed. Two empirical equations (a Speedy–Angell-type power-law equation and a newly developed equation incorporating temperature, density, and viscosity) were refitted based on simulation data. The overall relative errors are 4.52 % and 4.44 %, respectively, indicating an improved accuracy compared to conventional experimental and MD-based empirical equations.

关键词： Thermal conductivity

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Hydrothermal Hydrolysis Modeling of Lignocellulosic Biomass Using Subcritical Water for Test Packed Bed Reactor

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SSRN 2023年

作者： Wu, Zhonggang Wang, Jiawei Du, Xiaocheng Su, Hanguang China Nuclear Power Operations Co. Ltd. Shenzhen518116 China Department of Mathematics Physics and Electrical Engineering Northumbria University NewcastleNE1 8ST United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xi'An China School of Information Science and Engineering Northeastern University Shenyang China

In this paper, the subcritical water hydrothermal conversion process of lignocellulosic biomass as porous media in packed bed reactor was investigated by numerical simulation. The computational fluid dynamics mathematical modeling was used to describe the transient multi-physical fields formed during the instantaneous formation process of organic functional groups on the bases of experiment. The effect of inlet hydrothermal fluid velocity and temperature on the transient seepage flow, heat and transfer, and organic conversion reaction were investigated by ANSYS FLUENT® software. The results of the simulation indicate that the osmotic pressure and velocity increase with the hydrothermal fluid velocity and temperature. The surface heat transfer coefficient increases with the hydrothermal fluid velocity and temperature, and may reach the maximum within the scope of this paper. Both experimental and numerical simulation results consistently show that within the first 60 minutes of the hydrothermal reaction, the organic reaction rate is mainly determined by the combined model of turbulent-hydrothermal reaction. For a later time period after 60 minutes, the organic reaction rate mainly depends on the single model of hydrothermal reaction. Comparing the same experimental conditions and their real-time measurements, the numerical results in this paper accord with them. © 2023, The Authors. All rights reserved.

关键词： Porous materials

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Solution chemistry back‐contact FTO/hematite interface engineering for efficient photocatalytic water oxidation

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Chinese Journal of Catalysis 2022年第5期43卷 1247-1257页

作者： Karen Cristina Bedin Beatriz Mouriño Ingrid Rodríguez-Gutiérrez João Batista Souza Junior Gabriel Trindade dos Santos Jefferson Bettini Carlos Alberto Rodrigues Costa Lionel Vayssieres Flavio Leandro Souza The National Nanotechnology Laboratory(LNNANO) Brazilian Center for Research in Energy and Materials(CNPEM)Campinas 13083‐970Brazil Centro de Ciências Naturais e Humanas(CCNH) Federal University of ABC(UFABC)Santo André09210580Brazil Federal University of Rio Grande do Sul(UFRGS) Rio Grande do SulBrazil International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power EngineeringSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina

This work describes a simple yet powerful scalable solution chemistry strategy to create back‐contact rich interfaces between substrates such as commercial transparent conducting fluorine‐doped tin oxide coated glass(FTO)and photoactive thin films such as hematite for low‐cost water oxidation ***‐resolution electron microscopy(SEM,TEM,STEM),atomic force microscopy(AFM),elemental chemical mapping(EELS,EDS)and photoelectrochemical(PEC)investigations reveal that the mechanical stress,lattice mismatch,electron energy barrier,and voids between FTO and hematite at the back‐contact interface as well as short‐circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions,thus increasing the overall efficiency of these low‐cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water‐*** findings are of significant importance to improve the charge collection efficiency by minimizing electron‐hole recombination observed at back‐contact interfaces and grain boundaries in mesoporous electrodes,thus improving the overall efficiency and scalability of low‐cost PEC water splitting devices.

关键词： Nanostructure Iron oxide Water oxidation Photoanode Surface engineering Chemical synthesis

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Characterization of fluidization instability in the initial development stage of dense powder pneumatic conveying

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Physics of Fluids 2025年第5期37卷

作者： Yang, Shifan Gao, Shilin Zhao, Kunpeng Zhang, Haibin Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China

The startup characteristics of powder fuel conveyance significantly impact the reliable ignition of powder-fueled ramjet engines. By utilizing coupled computational fluid dynamics-discrete element method, this study took into full consideration the piston follow-up behavior, the interactions between solid particles and gas flow, as well as wall surfaces, and provided a more accurate analysis of the unsteady features during the initial development stage of dense powder conveying. The results show that the center-internal inlet exhibits superior powder conveying performance compared to that of the tangential-external and reverse-external inlets. While increasing fluidization pressure reduces conveying efficiency, it accelerates the stabilization process. Reducing the wall friction coefficient enhances the startup fluctuation, and pre-filling the powder chamber with gas decreases the piston delay and prevents the sudden drop in powder mass flow rate. This study advances the understanding of the two-phase flow mechanisms in the powder supply system and provides a valuable foundation for optimizing structural designs and operational parameters. © 2025 Author(s).

关键词： flow of gases

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Rapid modeling of transient processes in hydrogen-blended natural gas pipelines featuring injection and withdrawal points

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International Journal of Hydrogen Energy 2025年

作者： Gong, Junhua Zhou, Chaoqun Wang, Yanxin Deng, Yajun Chen, Yujie Wang, Peng Yu, Bo Chen, Bin Yu, Zhipeng Wang, Bohong School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China Changqing Oil and Gas Transportation Branch of Northwest Company of PipeChina Xingqing District Ningxia Yinchuan City750004 China PipeChina Engineering Technology Innovation Co.Ltd Tianjin300450 China School of Petroleum Engineering Yangtze University Wuhan430100 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National & Local Joint Engineering Research Center of Harbor Oil & Gas Storage and Transportation Technology/Zhejiang Key Laboratory of Pollution Control for Port-Petrochemical Industry Zhejiang Ocean University Zhoushan316022 China

Blending hydrogen into natural gas pipelines enables the large-scale delivery and application of hydrogen, contributing to carbon emission reduction and promoting the transition to cleaner energy sources. Accurate and efficient predictions of transient processes in such pipelines are critical for effective management and operation. This study proposes a Fourier Neural Operator (FNO)-based model for the rapid prediction of transient processes in hydrogen-blended pipelines with injection and withdrawal points. The model is trained using numerical simulation data of pressure and flow dynamics, with initial conditions, boundary conditions, and the hydrogen blending ratio as inputs to predict hydraulic parameters along the pipeline over time. By optimizing data preprocessing and neural network hyperparameters, the model achieves high accuracy and efficiency in predicting hydraulic states. The FNO model achieves average Root Mean Squared Errors (RMSEs) of 1.06 × 10−3, 1.64 × 10−3, and 7.40 × 10−4 for pressure, flow rate, and density, respectively, with the Coefficient of Determination (R2) exceeding 0.99 for all three variables. Furthermore, the model demonstrates strong generalization capabilities, accurately predicting hydraulic states for pipeline topologies and scenarios beyond the training data. In these cases, the RMSE remains in the order of 10−3 or smaller. For a 100 km pipeline, the computational efficiency of the FNO model is at least 969 times higher than that of traditional numerical methods, with the maximum efficiency improvement reaching 5168 times as the number of pipeline cases simultaneously predicted increases. These results highlight the potential of the FNO model for real-time applications in hydrogen-blended natural gas pipeline management. © 2025 Hydrogen Energy Publications LLC

关键词： Mean square error

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Thermally induced non-coalescence of compound droplets

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Applied Thermal engineering 2025年 276卷

作者： Jianmei Zhao Xing Li Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi’an Jiaotong University Xi'an 710049 China

Compound droplets surrounded by a gaseous phase with different temperatures widely exist in industrial applications. Previous research has focused on thermally induced non-coalescence or delayed coalescence between two single-phase droplets or a droplet and a liquid bath. The primary mechanism is the levitated intervening pressure in the lubricating air layer between droplets, which is caused by the thermocapillary convection. In this study, the non-coalescence of two compound droplets in a cold ambient air environment is experimentally investigated. The thermocapillary mechanism manifests three distinct features. First, as the two compound droplets approach each other, the temperature of the contact side of each droplet increases because of reduced heat loss, a phenomenon termed as the contact-side heating effect. This creates a surface temperature gradient, inducing Marangoni stress and subsequent surface convection. Second, owing to the immiscibility of the two phases within each compound droplet, the thermocapillary convection develops independently in each phase, forming independent convection which cannot be observed in single-phase droplets . It was observed that the directions of the thermocapillary convection within the two droplets were correlated and always planar symmetric, which is different from the uncorrelated and opposite convection of two single-phase droplets. Third and most importantly, the thermocapillary convection in the oil phase entrains the air into the lubricating film between droplets, inhibiting their coalescence only when the oil/water interface is adjacent to the contact zone.

关键词： Compound droplet Non-coalescence Thermocapillary convection

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