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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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Curvature-property coupling governed heat transfer deterioration in supercritical helically coiled tubes: Mechanistic insights and mitigation strategies via structural parametrization

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International Journal of Thermal Sciences 2025年 215卷

作者： Chang, Fucheng Xin, Jiaxing Wu, Xiaoyi Li, Liwei Li, Huixiong Zhu, Yanlin National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China China Special Equipment Testing and Research Institute Beijing 100029 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd Shanghai 200233 China

The unique thermo-hydrodynamic coupling phenomena in the helically coiled tube (HCT) handling supercritical fluids present both opportunities and challenges for next-generation compact heat exchangers. While the pronounced thermophysical property variations near pseudo-critical temperatures (T_pc) and curvature-induced secondary flows synergistically enhance heat transfer coefficient (HTC), their nonlinear coupling mechanisms may unexpectedly provoke severe heat transfer deterioration (HTD). Through systematic numerical investigations, this study reveals that circumferential wall temperature inhomogeneity (CWTI) exhibits an inverted N-shaped evolution, providing valuable insights for thermal homogenization design near T_pc. The secondary flow Reynolds number (Se), quantifying secondary flow intensity, shows a monotonic increase with decreasing coil diameter (D_c) or inner diameter (D_i), reaching saturation in high-enthalpy regions. Notably, CWTI demonstrates non-monotonic behavior, achieving minimum values near T_pc before manifesting distinct rebound characteristics near T_pc conditions. Parametric analysis establishes that: (1) Elevating heat flux (q) increases Se, reducing D_c boosts it by 50.3 %, and decreasing D_i raises it by 60.0 %. (2) HTD predominantly initiates at the outer wall under high-q conditions, with D_c reduction achieving HTD suppression and 26.9 % enhancement in the local HTC;(3) Reducing the D_i results in a reduction of maximum CWTI by 22.5 %–28.6 %, suggesting that structural parametrization effectively mitigates wall temperature non-uniformity, thus suppressing the HTD. While centered on supercritical water, the dimensionless scaling relationships demonstrate extendibility to other media, with the curvature-property coupling mechanism both elucidating fundamental interactions and guiding robust heat exchanger design. © 2025 Elsevier Masson SA

关键词： Heat transfer deterioration Helically coiled tube Structural parametrization Supercritical fluid Thermo-hydrodynamic coupling

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Constructing electron transport channel of SnO2/BaSO4 on g-C3N4 for enhanced visible-light-driven photocatalytic H2 production

Materials Today Catalysis

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Materials Today Catalysis 2025年 9卷

作者： Dong, Gongyue Guo, Xiaojuan Cheng, Cheng Chen, Feng Zhang, Jinfeng Du, Yanping Meng, Wei Liu, Maochang Shi, Jinwen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Guangdong Provincial Key Laboratory of Multi-energy Complementary Distributed Energy Systems Dongguan University of Technology Dongguan523808 China School of Engineering Lancaster University LancasterLA1 4YW United Kingdom Gansu Company PipeChina Lanzhou730060 China Hunan Provincial Key Lab of Dark Tea and Jin-Hua Department of Material & Chemical Engineering Hunan City University Yiyang413000 China

Graphitic carbon nitride (g-C3N4) is confronted with the issue of poor utilization of photogenerated charge carriers, thereby leading to limited performance of photocatalytic hydrogen (H2) production, which restricts its potential application. Herein, the electron transport material SnO2/BaSO4 was synthesized to integrate with g-C3N4 for addressing the above problem. Various characterizations were conducted to investigate the g-C3N4-SnO2/BaSO4 photocatalyst, and it demonstrated that photogenerated electrons from g-C3N4 expeditiously migrate to SnO2/BaSO4 nanoparticles, which markedly hindered photogenerated carriers’ recombination. Subsequently, the g-C3N4-SnO2/BaSO4 photocatalyst demonstrated promoted photocatalytic H2 production at a rate of 14.2 μmol h−1 under visible-light illumination, which was 2.5 times higher than that of pristine g-C3N4. © 2025 The Authors

关键词： Barium sulfate

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Study on Venturi nozzle for gas-liquid two-phase flow metering

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Journal of Harbin Institute of Technology(New Series) 2012年第1期19卷 107-110页

作者：梁法春张修刚王栋林宗虎 College of Pipeline and Civil Engineering China University of Petroleum State Key Lab of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Experiments were carried out to study gas-liquid two-phase flow through a horizontally mounted Venturi nozzle. The inner diameter of pipe is 25 mm and the throat diameter of Venturi nozzle is 5. 1 mm. The pressure difference and pressure loss across the nozzle were measured. It was found that the degree of pressure fluctuation strongly depends on the gas quality. However,the relationship between the standard deviation of pressure difference and the gas quality is not monotonous. multiple solutions may occur when the relationship was used to determine gas quality. On the other hand,the standard deviation of pressure loss was found to be monotonously correlated to X. This phenomenon was applied to measured gas quality. Also a modified Lin's equation is proposed to calculate the two-phase flow rate. The experimental measurements agree well with the predicted values.

关键词： two-phase flow Venturi nozzle flow measurement

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A Least-Squares Solution to Nonlinear Steady-state Multi-Dimensional IHCP

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Journal of Thermal Science 1996年第1期5卷 39-41页

作者： Bai Bofeng Guo Liejin Chen Xuejun (state key lab of Multiphase flow in power engineering,Xi’an Jiao Tong University,Xi’an 710049,China) State Key Lab of Multiphase Flow in Power Engineering Xi’an Jiao Tong University Xi’an China

In this paper,the least-squares method is used to solve the Inverse Heat Conduction Problem(IHCP)to determine the space-wise variation of the unknown boundary condition on the inner surface of a helically coiled tube with fluid flow inside,electrical heating and insulation *** sensitivity coefficient is analyzed to give a rational distribution of the thermocouples. The results demonstrate that the method effectively extracts information about the unknown boundary condition for the heat conduction problem from the experimental measurements. The results also show that the least-squares method converges very quickly.

关键词： helically coiled tube least-squares method IHCP.

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Hydrogen production from co-gasification of coal and biomass in supercritical water by continuous flow thermal-catalytic reaction system

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 327-330页

作者： YAN Qiuhui GUO Liejin LIANG Xing ZHANG Ximin State Key Lab of Multiphase Flow in Power and Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Environmental and Municipal Engineering Xi'an University of Architecture and TechnologyXi'an 710055China State Key Lab of Multiphase Flow in Power and Engineering Xi'an Jiaotong UniversityXi'an 710049China

Hydrogen is a clean energy *** abundant coal sources and green biomass energy into hydrogen effectively and without any pollution promotes environmental *** co-gasification performance of coal and a model compound of biomass,carboxymethylcellulose (CMC)in supercritical water (SCW),were investigated *** influences of temperature,pressure and concentration on hydrogen production from co-gasification of coal and CMC in SCW under the given conditions (20-25 MPa,650℃,15-30 s) are discussed in *** experimental results show that H2,CO2 and CH4 are the main gas products,and the molar fraction of hydrogen reaches in excess of 60%.The higher pressure and higher CMC content facilitate hydrogen production;production is decreased remarkably given a longer residence time.

关键词： hydrogen production coal CMC supercritical water co-gasification

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Numerical simulation of ignition of coke-oven gas on an industry boiler

Numerical simulation of ignition of coke-oven gas on an indu...

引用

International Conference on Frontiers of Energy, Materials and Information engineering, ICFMEI 2014

作者： Shi, Hong Wei Wang, Shuai Wang, Dong Zhang, Xing Kai State key lab of multiphase flow in power engineering Xi'an jiaotong university Xi’an China

ISBN: (纸本)9783038352778

Some coking plants discharge coke-oven gas to the environment,this pollute the *** order to solute the problem,the paper proposed a method:using coke-oven gas instead of light oil to ignite the *** virtue of doing this was to save *** FLUENT software package to simulate ignition in boiler is a effective mean,it can show the distribution of temperature in the *** simulation result shows that using CFD methods can provide ideas for the operation of the boiler. © (2014) Trans Tech Publications, Switzerland.

关键词： Computational fluid dynamics

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Study of Heat Transfer in Ice-storage Tank

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Journal of Thermal Science 2001年第4期10卷 357-362页

作者： Anding HeHuanqun QianZhihua HuFangde Zhou state key lab of Multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an, 710049, China State Key Lab of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

The heat transfer process of ice formation on the outside of coil pipe in the ice storage tank with glycol solution as the second refrigerant was studied in this paper analytically and experimentally. A model was developed for the charging process and the conduction shape factor was applied. Also, the result obtained from the model was compared with the experimental data, both data were in agreement. The simple model is useful for the operation, design and optimization of the ice storage tank.

关键词： coil type ice storage charging rate shape factor.

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A research on ignition of a boiler by using coke-oven gas instead of light oil and alternation of the boiler

A research on ignition of a boiler by using coke-oven gas in...

引用

International Conference on Frontiers of Energy, Materials and Information engineering, ICFMEI 2014

作者： Shi, Hong Wei Zhang, Xing Kai Wang, Dong Wang, Shuai State key lab of multiphase flow in power engineering Xi’an jiaotong university Xi’an China

ISBN: (纸本)9783038352778

In order to solute the question of boiler ignition in thermal electrical factory of an Aluminun plant, Coke-oven gas was used to substitute for ligtht oil. At the same output of boiler, the cost of start up can be reduced;at low boiler output coke-oven gas can be used to ignite coal, and the ignition was steady. Once upon a time, the coke-oven gas was ignited directly in the air, it wasted energy and caused envirnmental pollution. The coke-oven gas guns were placed in the under secondary air and the middle secondary air, the output of single gas gun was 800Nm3/h;the virtue of the arrangement was to prevent coke-oven gas consuming so much air for the coal. © (2014) Trans Tech Publications, Switzerland.

关键词： Coke

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Hydrodynamic and heat transfer properties of magnetic fluid in porous medium considering nanoparticle shapes and magnetic field-dependent viscosity

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Chinese Journal of Chemical engineering 2020年第2期28卷 329-339页

作者： Mohsen Izadi Masoud Javanahram Seyed Mohsen Hashem Zadeh Dengwei Jing Mechanical Engineering Department Lorestan UniversityKhorramabadIran Mechanical Engineering Department Islamic Azad UniversityBushehrIran Department of Mechanical Engineering Shahid Chamran University of AhvazIran School of Energy and Power Engineering State Key Lab of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

The purpose of this paper is to study the characteristics of the combined convection heat transfer and a micropolar nanofluid flow passing through an impermeable stretching sheet in a porous *** nanofluid flow field is affected by a magnetic field perpendicular to the *** dynamic viscosity of the micropolar nanofluid changes under the influence of the magnetic *** continuity,linear momentum,angular momentum,and energy equations are first simplified using the order of magnitude technique that,along with the applied boundary conditions and the definition of the appropriate parameters,are transferred to the similarity space using the similarity *** the resulting equations are solved using the Runge–Kutta *** distinction of the macroscale and microscale flow fields and temperature fields resulting from different nanoparticle shapes was *** the Hartmann number,the vortex viscosity parameter,the magnetic parameter,the nanoparticle volume fraction,and the permeability parameter of the porous media increased the surface friction on the *** the vortex viscosity parameter,the magnetic parameter,and the volume fraction of the nanoparticles increases the Nusselt number.

关键词： MHD-combined convection Porous media Magnetic micropolar nanofluid

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