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

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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Experimental and simulation study of H2 crossover in PEM water electrolysis for high-pressure hydrogen production up to 20 MPa

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International Journal of Hydrogen Energy 2025年 135卷 499-506页

作者： Wu, Jiazhe Zhang, Guoao Dong, Boyu Chang, Yuhao Chen, Yubin International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi 710049 China

High-pressure proton exchange membrane (PEM) water electrolysis offers considerable advantages, particularly in enabling direct integration with hydrogen storage and transportation systems while eliminating the need for external mechanical compressors. However, H2 crossover is a bottleneck that induces high H2-in-O2 content and low overall efficiency during high-pressure PEM water electrolysis. This study investigates H2 crossover in PEM water electrolysis by combining in situ measurements and numerical simulations over a differential pressure range of 0–20 MPa. A linear correlation was observed between hydrogen crossover and current density within the range of 0–1 A cm−2. The cathodic hydrogen mass transfer coefficient was determined to range from 1.6 to 3.2 mm s−1, and the hydrogen solubility was estimated as 1.1 × 10−3 mmol m−3 Pa−1. The results highlight the importance of optimizing mass transfer and reducing hydrogen solubility within the cathode catalyst layer to mitigate H2 crossover during high-pressure PEM water electrolysis. © 2025 Hydrogen Energy Publications LLC

关键词： Diffusion in solids

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Hydrogen production performance optimization for direct-coupled photovoltaic electrolysis systems based on a novel 3D opto-electro-thermal model

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Applied Energy 2025年 392卷

作者： Wang, Hao Wang, Weiding Lin, Chuanjie Lai, Yongquan Li, Changchen Xu, Ziyou Yang, Yuanbo Yang, Yimin Dong, Wenxuan Su, Jinzhan International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi'an Jiaotong University Xi'an710049 China

Photovoltaic-powered electrolysis systems represent a promising approach for large-scale renewable energy storage, with direct-coupled systems offering particular advantages in terms of reduced system complexity and cost. However, a mismatch issue between photovoltaic (PV) and electrolysis (EC) modules of these systems could be caused by suboptimal structural design and flow rate control strategies, leading to a significant reduction in hydrogen production performance. While these problems could potentially be addressed through numerical simulation, existing low-dimension models are overly simplified due to the assumptions of spatial homogeneity, failing to adequately capture the intricate coupling mechanisms among optical, thermal, electrical and gas-liquid flow phenomena in these complex systems. In this study, a novel 3D opto-electro-thermal model has been developed for direct-coupled systems, utilizing semiconductor drift-diffusion equations and a gas-liquid two-phase flow model within each grid cell. This advanced model facilitates comprehensive performance assessments during the optimization of the fundamental system structure (PV-EC), including the evaluation of novel system configurations that integrate photovoltaic/thermal (PV/T) and contact-based thermal designs. Additionally, it could help to streamline flow rate control by optimizing the relative sizing between the membrane electrode assembly (MEA) of EC and PV modules. The results demonstrate that the PV/T-EC Non-thermal integration structure achieves the maximum Solar-to-Hydrogen efficiency (STH). Moreover, by setting the relative sizing at 2.25 %, maintaining the flow rate in a wide range without precise control could be sufficient to achieve outstanding and stable STH under real-world fluctuating conditions. This allows the flow rate control strategy to be effectively streamlined. The findings could provide guidance for optimizing hydrogen production performance by refining system structure and flow

关键词： Model structures

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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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Infectious cough droplet dynamics in a makeshift hospital isolation ward

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Physics of Fluids 2025年第2期37卷

作者： Norvihoho, Leslie Kojo Liu, Yi Yin, Jing Zhu, Xin-Gang Yu, Hai-Tao Wang, Qi-Di Chen, Bin Zhou, Zhi-Fu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China China Nuclear Power Engineering Co. Ltd. Beijing China

The COVID-19 pandemic highlighted the need for rapidly deployable healthcare facilities, leading to increased use of modular construction methods. Nonetheless, knowledge about airflow patterns and the spread of bioaerosols in these wards remains insufficient, potentially heightening the risk of cross-infection among healthcare workers and patients. This paper presents a ventilation design for a modular negative-pressure ward aimed at reducing the spread of infectious particles. We investigate the effects of various ventilation designs, patient postures (sitting and supine), and air changes per hour (ACH) on the spread of infectious cough droplets in an airborne infection isolation room using large eddy simulation and the Eulerian-Lagrangian model. Findings show that ceiling exhaust grilles (design 2) resulted in the lowest radial dispersion (3.64 m) at 12 ACH, while sidewall exhausts (baseline) performed best at higher ACH levels. Seated patients had quicker droplet evaporation compared to those in a supine position. The best setups for reducing droplet survival included exhaust grilles at the bed's bottom and ceiling, maintaining a minimum of 12 ACH. Cases 5 and 13, with grilles over the patient's head and at the bed's bottom, showed the lowest concentrations of DPM, under 0.008 km−3 near the source and less than 0.001 km−3 mid-room. Sitting posture consistently led to lower DPM concentrations. This research emphasizes the critical role of exhaust placement in reducing droplet re-circulation and transmission risks, ultimately contributing to improved ventilation strategies and infection control in AII rooms. © 2025 Author(s).

关键词： Ceilings

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Experimental study on heat transfer deterioration and critical heat flux of DNB type in helically coiled tubes

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International Journal of Thermal Sciences 2025年 215卷

作者： Chang, Fucheng Lou, Jiacheng Wu, Xiaoyi Li, Shuai Yang, Jiaqi Li, Xi Li, Huixiong National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China

Helically coiled tubes (HCTs) are extensively utilized in numerous engineering fields due to their exceptional heat transfer and structural capabilities. The thermal safety within HCTs is crucial for the long-term stable operation of heat transfer systems. The heat transfer deterioration and critical heat flux (CHF) of departure from nucleate boiling (DNB) type in the HCTs at subcritical pressure were experimentally studied in this paper. The special circumferential wall temperature distribution was obtained and the effects of inlet cooling, pressure, mass velocity and HCT orientation on CHF were investigated. As the inlet subcooling increased, the CHF increased almost linearly. As the mass velocity increased, the turbulence degree in the HCT increases significantly, bubbles were less likely to merge and accumulate, and the CHF increased substantially. It was found that the CHF in the vertical HCT was higher than that in the horizontal HCT under the same working conditions because of the combined action of gravity and centrifugal force. The CHFv/CHFh exhibits a reduction with elevated inlet subcooling and pressure, and the influence of mass velocity on CHFv/CHFh is related to the pressure. New orientation-specific CHF correlations for vertical and horizontal HCTs are developed, achieving high prediction accuracy across pressures of 16–20 MPa and mass fluxes of 320–560 kg m−2 s−1. These findings can provide theoretical support for the optimization design and safe operation of the HCT heat transfer systems. © 2025

关键词： Thermal engineering

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Molecular dynamics study on bubble nucleation characteristics on rectangular Nano-Grooved surfaces

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Journal of Molecular Liquids 2025年 420卷

作者： Li, Zhibin Lou, Jiacheng Wu, Xiaoyi Li, Xujun Chang, Fucheng Wang, Hengyuan Li, Huixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China

The micro/nanoscale structures on metal surfaces are of significant research interest for boiling heat transfer and exhibit great application potential in the thermal management of high-power electronic devices. This study employs the molecular dynamics simulation method to investigate the boiling heat transfer characteristics of hydrophilic rectangular shallow nano-groove structures, comparing them with the smooth surface. The phase transition heat transfer characteristics of liquid films on the smooth surface, single rectangular groove (SRG) surface, and overlapping rectangular groove (ORG) surface are revealed by analyzing the variations of parameters such as energy contour diagrams, bubble volume, liquid film temperature, and average potential energy. The research results indicate that water molecules are in a solid-like state within shallow grooves, while the nucleation sites of initial bubbles form randomly outside the grooves. During the initial heating and bubble growth, the initial nucleation time and bubble growth rate of ORG are slower than those of SRG, due to the small rectangular groove on ORG that diminishes the energy transfer efficiency. During bubble formation and growth, the average kinetic energy within the liquid film fluctuates at the nucleation moment in the critical nucleation region, and the average potential energy rises from −0.083 eV. These findings provide a theoretical basis for the micro/nanoscale structure design of vapor-liquid phase transition thermal management devices. © 2024 Elsevier B.V.

关键词： Kinetic energy

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Novel numerical method establishment and performance evaluation for rotary adsorption and desorption wheel for carbon capture

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Applied Thermal engineering 2025年 274卷

作者： Gao, Rongze Wang, Limin Wang, Chang'an Tang, Chunli Li, Yuhang Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Mechanical Engineering Xi'an Shiyou University Xi'an710065 China

Due to the great compactness and ease of operation, the rotary adsorption and desorption wheel (RADW) is applicable for carbon capture in power plants using temperature swing adsorption (TSA). Commercial CFD-based software such as Fluent is commonly used to evaluate the RADW performance but the computing time is too long. However, few studies have focused on the computational efficiency and stability of complicated coupled heat and mass transfer processes in the RADW. A detailed iteration format and method for independent programming is urgently needed for both rapid design calculation and real-time performance monitoring in power plants. A novel rapid solution method using the mixed implicit and explicit (MIE) strategy to achieve the cyclic steady state (CSS) in the rotary bed was proposed, which can be used for heat transfer, mass transfer, and the coupled transfer processes. A comparison in terms of accuracy and efficiency was made between Fluent and the proposed method. In order to illustrate the applicability and universality of the proposed method, characteristics of the mass and temperature distribution in the RADW packed with amine-functionalized G3M were obtained, and the effects of different parameters on the adsorption and desorption behavior of RADW were studied. The correlation for the adsorption efficiency calculation operation was fitted, with which the adsorption efficiency under different operating conditions can be quickly obtained. © 2025

关键词： Osmosis

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The influence of peak wave-channel clearance on performance characteristics of traveling wave pump

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Energy 2025年 325卷

作者： Li, Gucheng Zhu, Qianming Gu, Qingqing School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai200093 China

Pumped storage plays a significant role in addressing the intermittency associated with solar and wind energy. The research on pumped storage is vital for sustainable development, with the pump serving as a key component. Achieving efficient energy conversion necessitates advancements in pumped storage technology, specifically through the development of novel pump designs that overcome limitations such as cavitation and vibration associated with conventional pumps. This study introduces a traveling wave pump that utilizes a traveling wave motion mechanism within a vertical rectangular flow channel to lift water to higher elevations. A simplified two-dimensional traveling wave plate model is employed to examine the influence of peak wave-channel clearance on pump performance using numerical simulations. The findings indicate that reducing the clearance causes a linear increase in time-averaged efficiency and a corresponding decrease in volumetric loss. Under high head conditions, pump performance is particularly sensitive to variations in clearance. A reduction in clearance accelerates high-speed fluid flow above the contraction point while reducing the low-speed zone below it. Furthermore, it weakens the intensity of the high-speed vortex at the leading edge of the traveling wave plate and the leakage vortex beneath the contraction point. © 2025 Elsevier Ltd

关键词： Vortex flow

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Experimental Study on Heat Transfer Characteristics of Supercritical Carbon Dioxide in a Vertical Circular Tube

SSRN

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SSRN 2025年

作者： Yang, Haikuo Nie, Ruishan Zhang, Kui Tian, Wenxi State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

Supercritical carbon dioxide (S-CO2) nuclear energy and power systems have garnered significant attention for flow and heat transfer experiments because of their compact design, advanced circulation methods, and high thermal efficiency, aligning with future trends in nuclear power plant development. However, the dramatic change in physical properties of S-CO2 near its pseudo-critical point can lead to heat transfer deterioration (HTD) in heat exchangers, potentially damaging the S-CO2 Brayton system. This paper presents an experimental study on the HTD of S-CO2 in a vertical circular tube under forced circulation, examining how heat flux, inlet temperature, and system pressure influence *** analysis delves into the mechanisms of HTD, focusing on the buoyancy and flow acceleration effects. Additionally, the study explores the impact of heat flux and system pressure on S-CO2 natural circulation. Ultimately, the research summarizes the flow and heat transfer characteristics of S-CO2 and proposes a new heat transfer correlation formula, demonstrating an error margin within ±25%, which meets practical engineering requirements. This experimental study contributes valuable data to the understanding of flow and heat transfer phenomena in S-CO2, offering significant insights for future applications. © 2025, The Authors. All rights reserved.

关键词： Nuclear energy

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