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

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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In Situ Synthesis of Cu_(3)P/P-Doped g-C_(3)N_(4)Tight 2D/2D Heterojunction Boosting Photocatalytic H2 Evolution

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Chinese Journal of Chemistry 2023年第2期41卷 173-180页

作者： Fangyong Hou Feng Liu Haochen Wu Muhammad Qasim Yi Chen Yang Duan Zhibo Feng Maochang Liu International Research Center for Renewable Energy&State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'anShaanxi 710049China School of Electronic Engineering Jiujiang UniversityJiujiangJiangxi 332005China Gree Altairnano New Energy Inc ZhuhaiGuangdong 519040China Suzhou Academy of Xi'an Jiao tong University SuzhouJiangsu 215123China

Heterojunction design in a two-dimensional(2D)fashion has been deemed beneficial for improving the photocatalytic activity of g-C_(3)N_(4)because of the promoted interfacial charge transfer,yet still facing ***,we construct a novel 2D/2D Cu_(3)P nanosheet/P-doped g-C_(3)N_(4)(PCN)nanosheet heterojunction photocatalyst(PCN/Cu_(3)P)through a simple in-situ phosphorization treatment of 2D/2D CuS/g-C_(3)N_(4)composite for photocatalytic H2 *** demonstrate that the 2D lamellar structure of both CuS and g-C_(3)N_(4)could be well reserved in the phosphorization process,while CuS and g-C_(3)N_(4)in-situ transformed into Cu_(3)P and PCN,respectively,leading to the formation of PCN/Cu_(3)P tight 2D/2D *** to the large contact area provided by intimate face-to-face 2D/2D structure,the PCN/Cu_(3)P photocatalyst exhibits significantly enhanced charge separation efficiency,thus achieving a boosted visible-light-driven photocatalytic *** highest rate for H2 evolution reaches 5.12 umol·h^(-1),nearly 24 times and 368 times higher than that of pristine PCN and g-C_(3)N_(4),*** work represents an excellent example in elaborately con-structing g-C_(3)N_(4)-based 2D/2D heterostructure and could be extended to other photocatalyst/co-catalyst system.

关键词： Photocatalysis Water splitting 2D/2D heterojunction g-C_(3)N_(4) Energy conversion Charge transfer Nanosheet photocatalyst

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Assessment on the rings cleavage mechanism of polycyclic aromatic hydrocarbons in supercritical water: A ReaxFF molecular dynamics study

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Journal of Molecular Liquids 2024年 415卷

作者： Zhao, Hao Zhang, Yingjia Zhou, Shumei Chen, Ruiqi Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No. 28 Xianning West Road Shaanxi Xi'an710049 China

The ring opening reaction of polycyclic aromatic hydrocarbons (PAHs) is one of the rate-determining steps of coal gasification within supercritical water, while the involvement of water remains debated between addition and hydrogen abstraction theories. In this study, reactive molecular dynamics (MD) simulations were performed to explore the ring opening reaction of naphthalene, the simplest PAH, at temperatures of 2500–2700 K. Species and elementary reactions were quantitatively extracted from bond order trajectories using an in-house program. Reaction path analysis shows that ring opening paths of naphthalene mainly include thermolysis, H˙ atom abstraction, and O˙H radical addition. Flux analysis indicates O˙H radical largely from the H˙ + [Formula presented] = O˙H + [Formula presented] reaction, while the water dissociation [Formula presented] = O˙H + H˙ reaction is near equilibrium, seldom contributing to the O˙H source. This atomistic kinetics analysis is intended to help the modeling of supercritical water gasification of coal. © 2024 Elsevier B.V.

关键词： Naphthalene

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Deactivation of V2O5–WO3–TiO2 SCR Catalyst by HF During Co-Firing Electrolytic Aluminum Waste with Coal 9th

Deactivation of V2O5–WO3–TiO2 SCR Catalyst by HF During Co...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Zhu, Zhengrong Ma, Shihao Wang, Yikun Zhang, Yan Qiu, Yuxiao 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 Institute Co. Ltd Xi’an710032 China

ISBN: (纸本)9789811616563

Fluorine-containing waste from the electrolytic aluminum industry would cause environmental pollutions if the waste is improperly disposed. It is important and urgent to develop a harmless treatment method for the waste. In this paper, co-firing electrolytic aluminum waste with coal was studied. And the deactivation of V2O5–WO3–TiO2 SCR catalyst by HF was investigated by a lab-scale experimental system. The results show that HF is harmful to the catalyst. The denitrification efficiency of catalyst sample which treated by flue gas with HF is reduced. The denitrification efficiency of sample increases with increasing work temperature and deactivation temperature. When the work temperature is 400 °C, the denitrification efficiency of catalyst sample is higher than 90%. Analysis by temperature programmed desorption of ammonia (NH3-TPD), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) show the definite dispersion of F on the surface of SCR catalysts. HF would lead to decrease specific surface areas, surface acidity, and oxidation–reduction ability. Although the concentrations of Oβ (surface adsorbed oxygen) increases owing to HF, which may interact with TiO2 to destroy the carrier structure. Meanwhile, there is a chemical deactivation for the influence of HF on V2O5 and WO3. © 2022, Tsinghua University Press.

关键词： Titanium dioxide

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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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Numerical Study on Combustion and NOx Emission Characteristics of Co-Firing Semi-Coke and Coal in a Tangentially-Fired Utility Boiler 9th

Numerical Study on Combustion and NOx Emission Characteristi...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Feng, Qinqin Wang, Chang’an Wang, Pengqian Wang, Zhichao Yao, Wei Zhao, Lei Du, Yongbo 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 Institute Co. LTD Xi’an710054 China

ISBN: (纸本)9789811616563

With the booming coal industry and the increasing production of semi-coke, a large number of small particles and powder pyrolysis semi-coke are urgent to be exploited. Co-firing semi-coke with coal is a potential approach to achieve clean and efficient utilization of such low-volatile fuel. In this paper, the co-combustion performance of semi-coke and coal in a 135 MW tangentially-fired boiler was investigated by numerical simulation. The influences of semi-coke blending ratio, blending mode and injection position on the combustion efficiency and NOx generation characteristics of the utility boiler were extensively analyzed. The simulation results indicated that the NOx emission at the furnace outlet was elevated and the burn-out ratio declined with an increase in semi-coke blending ratio. Different heights of semi-coke injected position could lead to different combustion efficiency and NOx emissions. The semi-coke was recommended to be injected from the middle layer of burners to obtain low carbon content in fly ash. The blending methods (in-furnace versus out-furnace) had certain impacts on the NOx emission and carbon content in fly ash. High burn-out ratio could be obtained when the semi-coke and coal were injected from different burners. © 2022, Tsinghua University Press.

关键词： Coal

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Comparative Life Cycle Analysis of Battery Energy Storage Technologies for Grid Applications: Case Study in China 35

Comparative Life Cycle Analysis of Battery Energy Storage Te...

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35th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2022

作者： Han, Xiaoqu Li, Yanxin Chang, Hongzhang Chen, Nana Huang, Xiaofan Tang, Xiaoping Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China Huadian Electric Power Research Institute Co. Ltd. Beijing China

ISBN: (纸本)9788774756989

With ever increasing penetration of renewable energy sources into the power grid, the development and commercialization of large-scale energy storage system (ESS) have been accelerated. It is of great significance to evaluate the sustainability of ESSs for grid applications. In the present work, a comprehensive life cycle inventory analysis model, which involves the manufacturing, usage, transportation and recycling processes, was developed for lithium iron phosphate battery (LIPB), nickel manganese cobalt oxide battery (NMCB) and vanadium redox flow battery (VRFB). The functional unit was 1MWh of delivered energy from ESS to the grid. The ReCiPe 2016 (H) method was selected and data analysis was carried out in SimaPro software. The global warming potential (GWP) of LIPB, NMCB and VRFB in the grid peak-shaving scenario were obtained as 129 kgCO2-eq/MWh, 146 kgCO2-eq/MWh and 365 kgCO2-eq/MWh, respectively. GWP of different batteries in renewable energy sources (photovoltaic and wind power) was also predicted based on the developed model. The key materials that contributed significantly to GWP were also identified. Moreover, the future trend in GWP was analyzed based on the carbon peaking and carbon neutrality goals. It is indicated that GWP of LIPB, NMCB and VRFB in the announced pledges scenario could be reduced to approximately 75% in 2030, and 24%~41% in 2050, respectively. Parametric analysis was then carried out, indicating that the round-trip efficiency and number of daily cycles exhibited the significant influence. The results would promote the environment, policy and business model optimization for large-scale energy storage in the low-carbon power systems. © Proceedings of ECOS 2022 - 35th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems.

关键词： Life cycle

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Numerical Analysis of Thermal-Hydraulic Characteristics of the Whole Lfr Core Under Blockage Conditions

SSRN

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SSRN 2024年

作者： Yu, Jiacheng Liu, Kai Qiu, Hanrui Wang, Mingjun Tian, Wenxi Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi’an Jiaotong University Xi’an China

Blockage accidents are critical scenarios in the design and safety analysis of lead-bismuth cooled fast reactor (LFR) core. Traditional analysis of blockage accidents in LFR focuses on localized, fine-scale computational fluid dynamics (CFD) simulations of single or three assemblies, but the analysis of the whole core scale impact caused by blockage accidents is insufficient. Therefore, this paper uses CorTAF-LBE, a three-dimensional thermal-hydraulic analysis code developed by XJTU-NuTHeL, to analyze the impact of blockage accidents on the whole core of the LFR. The reliability of the code in calculating thermal-hydraulic parameters under blockage accidents was validated based on the KALLA-THEADES and KALLA-IWF experiments. Taking the MYRRHA-FASTEF core as the object, simulations and analyses are conducted for various blockage scenarios with different lengths and positions. The results indicate that blockage accidents lead to an enlarged coolant temperature gradient at the core outlet. Lengthening the blockage results in an elevation of the peak temperature in the cladding. Under 2.06% blockage at the center of the assembly, blockage in the middle of the heating segment poses the greatest threat to cladding integrity, with the maximum temperature reaching 1336.9K, an increase of 635.4K compared to normal operating conditions. Under 4.59% blockage at the edge of the assembly, the maximum cladding temperature reaches 1381.8K, and the heat transfer rate of the inter-wrapper flow (IWF) adjacent to the blockage area is 24.2% higher than under normal operation. Additionally, severe degradation in heat transfer downstream was not observed in several simulated blockage scenarios. © 2024, The Authors. All rights reserved.

关键词： Fast reactors

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Experimental study on the influence of the temperature and thermal Stress of water wall in different arrangements of burners

Experimental study on the influence of the temperature and t...

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International Conference on power engineering 2021, ICOPE 2021

作者： Wei, Lin Zhou, Qulan Liu, Zhuhan Li, Na State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

To study the water walls' safety problems of the opposed firing boiler, thermal experiments for four typical arrangements of burners conditions are run in a laboratory-scale boiler. The four working conditions include 25% rated load (four burners are arranged side by side on the front wall), 50% rated load (eight burners are all arranged on the front wall;eight burners are arranged opposed to each other on the front and rear walls) and 100% load (front and rear walls are filled with sixteen burners). The principal strain, principal stress and temperature distribution of the water wall under four operating conditions are drawn for comparison and analysis. In addition, the results of the thermal stress, principal main stress direction and water wall temperature of the four working conditions are counted respectively to summarize the laws of them. This study highlights the influence of the temperature and thermal stress on water walls in different arrangements of burners to guide the safe operation of water walls in the real opposed firing boiler. © 2021 The Japan Society of Mechanical Engineers.

关键词： Thermal stress

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Development of a three-dimensional method for thermal-hydraulics/neutronics coupling analysis and its application on CFETR helium-cooled solid breeder blanket

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 154-165页

作者： Lian, Qiang Tian, Wenxi Qiu, Suizheng Su, G.H. Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Blankets are of practical importance in the fusion reactor due to their main functions for engineering application. As the fusion power designed for the Chinese Fusion engineering Test Reactor (CFETR) is increased from 200 MW to 1.5 GW during its phase II operation, more challenges are issued for blankets from the points of view of thermal-hydraulics, neutronics, mechanics, and safety. In this paper, the Coupling Analysis of Thermal-hydraulics and Neutronics Interface Code (CATNIC) was developed using the user-defined function (UDF) in the CFD software FLUENT. The explicit coupling scheme based on cell-to-cell mapping approach was adopted to transfer data between neutronics calculation and thermal-hydraulics simulation. Three-dimensional thermal-hydraulic model and neutronics model were established using Fluent and MCNP4C, respectively. The helium-cooled solid breeder (HCSB) blanket of CFETR was simplified as a slice model to reduce the computing resources. With the slice model of CFETR HCSB blanket, the coupling analysis was carried out using the developed CATNIC. The calculation results from coupling and non-coupling analyses were compared to verify the feasibility of the coupling method in this study. As the helium coolant was considered as the transparent medium for neutron, the thermal-hydraulic and neutronics analyses were both converged after two iterations. However, using the developed coupling method in this study, the detailed change of tritium production ratio (TPR) and nuclear heat deposition in different parts of the blanket was revealed, which could provide important guidance for the design of the distribution for both coolant and purge gas. © 2021 Xi'an Jiaotong University

关键词： Coolants

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