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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

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

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

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

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

Thermally induced non-coalescence of compound droplets

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Applied Thermal engineering 2025年 276卷

作者： Zhao, Jianmei Li, Xing Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 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. © 2025 Elsevier Ltd

关键词： Drop formation

Experimental and Kinetic Modeling Study on the Oxidation and Laminar Combustion Characteristics of Natural Gas

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SSRN 2023年

作者： Chen, Xiaoxiao Zeng, Wen Zheng, Weilin Hu, Erjiang Ma, Hongyu Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace University Liaoning Shenyang110136 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shanxi Xi'An710049 China AECC Shenyang Engine Research Institute Shenyang110015 China

The oxidation process in the flow tube reactor at the conditions of P=0.1 MPa, T=500-1850 K, f=0.5, 1.0, 3.5, and the laminar combustion process in the constant volume combustion bomb at the conditions of P=0.1, 0.2, 0.3 MPa, T=300, 350, 400 K, f= 0.7-1.4, the O2 contents of 15%, 18% and 21%, the CO2 and H2O contents of 0%, 10%, and 20% of natural gas (0.9 methane/0.07 ethane/0.03 propane, mole fraction) were experimental tested. In the oxidation process of natural gas, with the equivalence ratio increasing, the starting and ending temperatures for oxidation reaction of natural gas are increased, the reaction temperatures corresponding to CO generation and consumption are higher, and the amount of NO production is decreased. In the the laminar combustion process of natural gas, at the conditions of higher pressure, equivalence ratio, CO2 and H2O contents, the flame front is not smooth as a large number of cracks and cell structures appear, and the flame is unstable. Moreover, with the initial temperature and oxygen content increasing or the initial pressure, CO2 and H2O contents decreasing, the laminar flame speed is increased. Furthermore, combined the path sensitivity analysis, rate of production analysis, reaction path analysis and the decoupling method, a reduced reaction mechanism (including 40 species and 189 reactions) of natural gas was developed. Through comparing with the calculated results by the Aramco 2.0 mechanism and the corresponding test data, the reduced reaction mechanism can well predict the oxidation, ignition delay and laminar combustion characteristics of natural gas under various conditions. © 2023, The Authors. All rights reserved.

关键词： Sensitivity analysis

Research on a Poly-Generation System for Gas-Biochar-Heat-Electricity by Supercritical Water Gasification of Biomass Waste

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SSRN 2024年

作者： Wang, Cui Jin, Hui School of Water and Environment Chang'an University Xi’an710054 China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education Chang'an University Xi’an710054 China Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources Chang’an University Xi’an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Ministry of Education of China Chongqing University Chongqing400044 China

Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent attention. Supercritical water gasification (SCWG) process is a potential technology. In this work, a poly-generation system based on SCWG was developed to convert biomass waste to gas, biochar, heat and electricity. Firstly, mass, energy, and exergy flow were calculated at the typical condition. Subsequently, impact of various operating parameters, including gasification temperature, mass flowrate of preheated water, biomass concentration, on the hydrogen-rich syngas yield, generated electricity, thermodynamic performance of the system was investigated. The result demonstrated that the exergy loss primarily occurred on cooler, reactor, heat exchanger and preheater, accounting for more than 90% of total exergy loss under different conditions, arising from irreversible reaction, heat transfer and heat dissipation. Higher temperature, higher biomass concentration and more preheated water exerted a positive effect for hydrogen-rich gas production and supplied heat energy, while these parameters were disadvantageous to exergy efficiency. Biochar energy was primarily affected by biomass concentration. Energy efficiency increased with preheated water quantity and biomass concentration rising, and impact of biomass concentration was more significant. Conversely, evaluated gasification temperature displayed an adverse effect on energy efficiency. The maximal exergy efficiency reached about 58.3% at 550℃, biomass concentration of 33%, preheated water mass flowrate of 900 kg·h-1 © 2024, The Authors. All rights reserved.

关键词： Biomass

Multi-parameter optimization to improve the erosion resistance of coating by FE simulation

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Multi-parameter optimization to improve the erosion resistan...

ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, GT 2021

作者： Li, Fang Wang, Shunsen Cai, Liuxi Feng, Zhenping State Key Laboratory of Multiphase Flow in Power Engineering Institute of Turbomachinery Xi'an Jiaotong University No. 28 Xianning West Road Xi'an710049 China School of Chemical Engineering and Technology Xi'an Jiaotong University No. 28 Xianning West Road Xi'an710049 China

ISBN: (纸本)9780791885000

Finite element method (FEM) was used to study the stress peak of stress S11 (Radial stress component in X-axis) on the steam turbine blade surface of four typical erosion-resistant coatings (Fe2B, CrN, Cr3C2-NiCr and Al2O3-13%TiO2). The effect of four parameters, such as impact velocity, coating thickness, Young's modulus and Poisson's ratio on the stress peak of stress S11 were analyzed. Results show that: the position of tensile stress peak and compressive stress peak of stress S11 are far away from the impact center point with the increase of impact velocity. When coating thickness is equal to or greater than 10μm, the magnitude of tensile stress peak of stress S11 on the four coating surfaces does not change with the coating thickness at different impact velocities. When coating thickness is equal to or greater than 2μm, the magnitude of tensile stress peak of stress S11 of four coatings show a trend of increasing first and then decreasing with the increase of Young's modulus. Meanwhile, the larger the Poisson's ratio, the smaller the tensile stress peak of stress S11. After optimization, When coating thickness is 2μm, Poisson's ratio is 0.35 and Young's modulus is 800 GPa, the Fe2B coating has the strongest erosion resistance under the same impact conditions, followed by Cr3C2-NiCr, CrN, and the Al2O3-13%TiO2 coating, Al2O3-13%TiO2 coating has the worst erosion resistance. Copyright © 2021 by ASME.

关键词： Finite element method

Solar-Wind Energy Complementary Coupling Realizes Magnetic-Field Assisted Efficient Photocatalytic Co2 Reduction

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SSRN 2023年

作者： Kong, Biao Ren, Yuqi Liu, Maochang Zhou, Jiancheng Wang, Ke Wang, Nan Li, Naixu School of Chemistry and Chemical Engineering Southeast University No.2 Dongnandaxue Road Jiangsu Nanjing211189 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Shaanxi Xi'An710049 China

We report the synthesis of a Z-scheme monolithic photocatalyst in the form of copper foam supported TiO2 combining Cu2O and Ag nanoparticles (CF@TiO2/Cu2O-Ag). The designed catalysts with efficient charge separation show superior photocatalytic activity toward CO2 reduction, with a maximum CO yielding rate of 25.58 μmol‧g-1‧h-1. More importantly, we develop a solar-wind energy complementary device, which enables the strong coupling of the magnetic field into the photocatalytic reaction. Specifically, the in-situ space electric field generated from the wind-driven induced electromotive force further enhances the separation and transportation of photogenerated charge carriers in the Z-scheme system. The productivity of CO in the proof-of-concept device based on the use of CF@TiO2/Cu2O-Ag catalyst reaches 71.66 μmol‧g-1‧h-1. This study provides an ideal approach for reinforcing photocatalytic CO2 reduction through muti-field coupling and highlights the prospect of solar-wind energy coupled photocatalysis. © 2023, The Authors. All rights reserved.

关键词： Titanium dioxide

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