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Investigation on turbulent characterization of arrayed micro-tube premixed hydrogen flames using an enhanced flamelet library

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Applied Thermal engineering 2025年 275卷

作者： Han, Xiao Yin, Yanxu Wang, Bosen Chang, Yunxin Cai, Xiao Research Institute of Aero-Engine Beihang University Beijing100191 China National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics Beihang University Beijing100191 China Collaborative Innovation Center for Advanced Aero-Engine Beihang University Beijing100191 China Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an710049 China

Lean turbulent premixed hydrogen/air flames exhibit increased flame wrinkling and significantly enhanced flame speeds, posing challenges for stable combustion. In the novel arrayed multi-flame burner, flame instabilities are intensified by flame-flame interactions. This study develops a distributed and efficient numerical framework for the Large Eddy Simulation-Flamelet Generated Manifold (LES-FGM) method, incorporating an improved 1D flamelet library. The framework is applied to investigate flame dynamics in both bluff-body and conical flame systems under varying equivalence ratios (= 0.4–0.7) and Karlovitz numbers (Ka = 1–100). By accounting for preferential diffusion, thermal-diffusive instability, and heat loss in stretched flames, the framework improves the accuracy of the flamelet library and captures key physical effects. 1D simulations are performed to validate and analyze the influence of differential diffusion on flame characteristics. The impact of transient flame stretching is analyzed in detail, revealing its critical role in stability transitions across varying turbulence intensities. Additionally, this study examines turbulence effects and micromix multi-flame interactions. The flame stretch factor varies from 1.1 to 2.4 in these three cases. At lower equivalence ratios, higher Ka suppresses tip-opening but intensifies small-scale flame wrinkling. Flame pocket detachment becomes more frequent. Vortex interactions play a key role in flame instability. The strain rate of conical flames is 40 % lower than that of bluff-body flames. These findings provide novel insights into flame dynamics in multi-flame burner arrays, which are critical for optimizing combustion performance in gas turbine combustors. © 2025 Elsevier Ltd

关键词： Large eddy simulation

Insight into the key Role of Imine Groups in Polyaniline for Adsorbing Heavy Metal Ions: Experimental and Density Functional Theory Study

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SSRN 2023年

作者： Shi, Bofang Li, Hang Fu, Xiaojie Zhao, Chengcheng Rao, Yongfang Li, Mingtao Komarneni, Sridhar Yang, Honghui Xi’an Key Laboratory of Sustainable Energy Materials Chemistry Department of Applied Chemistry School of Chemistry Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Ecosystem Science and Management Materials Research Institute 204EEL The Pennsylvania State University University ParkPA16802 United States

In polyaniline (PANI) or polyaniline-based adsorbents, the views on nitrogen group that has the highest chemical affinity to heavy metal ions and dominates the adsorption process remain in debate. Herein, we focus on deciphering the main adsorption sites and adsorption mechanism of PANI using both experiments and density functional theory (DFT) calculations. The characterization results of adsorption product demonstrate that the metal ions were adsorbed via coordination bond between nitrogen atom and metal ion. The theoretical calculations by DFT reveal that −N= group is the key adsorption site rather than other groups in PANI, and the key step of PANI adsorption process is a ligand exchange reaction. The H+ ions with a higher affinity to −N= group can inhibit the adsorption of metal ions due to the consumption of adsorption sites and ion exchange reaction. This work provides a molecular-level understanding of adsorption sites, adsorption mechanism, and H+ competition for metal ion adsorption by PANI, which is beneficial for the development of PANI-based adsorbents. © 2023, The Authors. All rights reserved.

关键词： Density functional theory

Study on the effect of particle flow state on the stability of LIBS carbon content detection signal 7

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Study on the effect of particle flow state on the stability ...

7th International Conference on power engineering, ICOPE 2019

作者： Pan, Yuqing Hu, Zhengtao Xu, Heng Zhou, Qulan Li, Na Deguchi, Yoshihiro State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Graduate School of Engineering Science Osaka University Japan

Rice husk, a type of biomass fuel, is rich in amorphous silica. Laser-induced breakdown spectroscopy (LIBS) is a fast-responding non-contact detection method which can realize on-line detection of rice ash components. This paper aims to explore the optimum working conditions of LIBS and extend the compatibility of LIBS technology. The paper uses the sample motion state simulation system to simulate ash, so that the particles can be laser-induced breakdown during the vertical drop and horizontal motion, and then the effect of particle flow state on the stability of the LIBS detection signal can be determined. In addition, the paper compares the effects of two laser pulse widths on the stability of LIBS detection signal by using a 1 ns pulse width laser and a 6 ns pulse width laser to improve the detection error. Experimental studies have found that long pulse width laser provides better stability of spectrum, and the relative standard deviation (RSD) of the detection result is smaller than that of short pulse width laser, and the RSD is smaller in the state of horizontally transferring samples, which can obtain the spectral signal with stronger line intensity. Moreover, sample in conveyor, by contrast, leads to more stable signals. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Stability

Two-Phase flow Dynamics in the Coupling Region of Gas Diffusion Layer and Patterned Wettability Metal Foam flow Field in Proton Exchange Membrane Fuel Cells

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SSRN 2024年

作者： Lv, Xuecheng Zhou, Zhifu Wu, Wei-Tao Wei, Lei Gao, Linsong Lyu, Jizu Li, Yang Yang, Yunjie Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation 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

In this study, the 3D structures of the gas diffusion layer (GDL) and metal foam flow field (MFF) in proton exchange membrane fuel cells (PEMFCs) were reconstructed by X-ray computed tomography, and the two-phase flow in the GDL-MFF coupling region was simulated by phase-field Lattice Boltzmann method (LBM). A comparative analysis of the two-phase flow characteristics was conducted between hydrophobic metal foam (HMF) and patterned wettable metal foam (PWMF). The effect of the wettability and size of the hydrophilic regions in PWMF was investigated. The results demonstrate that PWMF offers several advantages, including rapid removal of liquid water at the GDL-MFF interface, low liquid water coverage at the GDL-MFF interface, enhanced vertical gas convection in the GDL, low and stable pressure drop in the MFF, stable gas turbulent intensity in the MFF, and a more uniform gas velocity distribution. However, PWMF may slow down the transport of liquid water from the GDL to the MFF, increase the water saturation in the GDL, and reduce the drainage rate of the flow field. Proper adjustment of the contact angle and size of the hydrophilic regions in PWMF can alleviate these drawbacks. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

Xct Images-Based Modeling for Elucidating Electrochemical Inert Phase-Dependent Multiscale Electrode Kinetic Behaviors

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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

Insight into the key Role of Imine Groups in Polyaniline for Adsorbing Heavy Metal Ions: Density Functional Theory and Experimental Study

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SSRN 2023年

作者： Shi, Bofang Li, Hang Fu, Xiaojie Zhao, Chengcheng Wang, Angelina H. Tan, Weilin Rao, Yongfang Li, Mingtao Komarneni, Sridhar Yang, Honghui Xi’an Key Laboratory of Sustainable Energy Materials Chemistry Department of Applied Chemistry School of Chemistry Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Ecosystem Science and Management Materials Research Institute 204EEL The Pennsylvania State University University ParkPA16802 United States

In polyaniline (PANI) or PANI-based adsorbents, views on which nitrogen group has the highest chemical affinity to heavy metal ions and dominates the adsorption process remain in debate. Herein, we focus on deciphering the main adsorption sites and adsorption mechanisms of PANI using both density functional theory (DFT) calculations and experiments. The theoretical DFT calculations reveal that −N= group, rather than other groups within PANI, is the adsorption site. And the key step of PANI adsorption process is a ligand exchange reaction. In addition, H+ ions with a higher affinity to −N= group can inhibit the adsorption of metal ions through the consumption of adsorption sites and ion exchange reaction. X-ray photoelectron spectra (XPS) spectra demonstrate that maintaining a reasonably high pH value (pH > 4) is an effective way to weaken H+ competition. This work provides a molecular-level understanding of adsorption sites, adsorption mechanism, and H+ competition for metal ion adsorption by PANI, which is beneficial for the development of PANI-based adsorbents. © 2023, The Authors. All rights reserved.

关键词： Adsorption

Adsorption of Dibenzofuran by Modified Biochar Derived from Microwave Gasification

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SSRN 2024年

作者： Ren, Jiyun Zhang, Yong Wang, Hui Huang, Xiaoming Jin, Xiaoling Zhang, Kai Li, Ruiyu Yang, Kaixuan Yue, Yang 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 Yantai Longyuan Power Technology Co. Ltd Yantai264000 China West Pipeline Company of PipeChina Urumchi830000 China Jinggangshan Power Plant Huaneng Power International Inc Jiangxi 343009 China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528300 China Shanghai Power Equipment Research Institute Co. Ltd. Shanghai200240 China

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating and microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques including BET, X-ray CT, SEM-EDS, FTIR, and XPS are performed to identify the DBF adsorption mechanism on biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. Higher porosity (16.94%) and lower mineral content (1.75%) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11%) > KOH-modified CSC (77.14%) > unmodified CSC (49.11%) > unmodified OC (39.70%) > HNO3-modified CSC (36.09%). The adsorption mechanisms of DBF on the gasified biochar encompass pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously. © 2024, The Authors. All rights reserved.

关键词： Potassium hydroxide

Atomic Nickel on Graphitic Carbon Nitride as a Visible Light-Driven Hydrogen Production Photocatalyst Studied by X-ray Spectromicroscopy

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ACS Sustainable Chemistry and engineering 2023年第14期11卷 5390-5399页

作者： Huang, Yu-Cheng Li, Yanrui Arul, K. Thanigai Ohigashi, Takuji Nga, Ta Thi Thuy Lu, Ying-Rui Chen, Chi-Liang Chen, Jeng-Lung Shen, Shaohua Pong, Way-Faung Dong, Chung-Li Chou, Wu-Ching Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Research Center for X-ray Science & Department of Physics Tamkang University New Taipei City25137 Taiwan International Research Center for Renewable Energy State Key laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukabu305-0801 Japan UVSOR Synchrotron Facility Institute for Molecular Science Okazaki444-8585 Japan National Synchrotron Radiation Research Center Hsinchu30010 Taiwan

The photocatalytic production of solar hydrogen through water splitting by graphitic carbon nitride (g-C3N4) has gained substantial interest due to its advantageous characteristics, such as eco-friendliness, wealth on the earth, favorable bandgap, and easy preparation. Nevertheless, the performance for photocatalytic overall water splitting has been significantly restricted owing to the rapid recombination of charge carriers and slow catalytic kinetics. This investigation demonstrates the utilization of a single-atom Ni-terminating agent to coordinate with the heptazine moieties of g-C3N4, resulting in the formation of a new electronic orbital. g-C3N4 with single-atom Ni-termination can achieve highly efficient photocatalytic overall water splitting into H2 and H2O2 upon visible light irradiation, without requiring the use of any additional cocatalysts. The underlying cause of the enhanced photocatalytic performance of single-atom Ni-incorporated g-C3N4 in hydrogen evolution reaction is identified using synchrotron X-ray spectroscopy and microscopy. The X-ray spectro-microscopic results discover that the new hybrid orbital that is critical for optimizing photocatalysis is associated with carbon defects. The atomic and electronic structures and the band gap of g-C3N4 are adjusted by the new hybrid orbital. Moreover, it synergistically enhances visible light absorption, thereby promoting the separation and transfer of photogenerated charge carriers. The single-atom Ni and the adjacent C atom are recognized as the active sites for water oxidation and reduction, respectively, supporting the efficient photocatalytic splitting of water via a two-electron transfer pathway. This study demonstrated a promising material design for promoting photocatalytic activity in solar energy conversion applications. © 2023 American Chemical Society

关键词： Electronic structure

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