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SSRN 2024年

作者： Li, Jiazheng Li, Yanqiong Zeng, Wen Bai, Bofeng Ren, Shan College of Materials Science and Engineering Chongqing University Chongqing400030 China School of Electronic information & Electrical Engineering Chongqing University of Arts and Sciences Chongqing400030 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

MXene materials have exhibited potential in electrochemistry, particularly in gas sensing, due to their excellent conductivity, large specific surface area of layered materials, and unique functional groups. However, the gas sensing performance of intrinsic 2D MXene materials is often limited by their fluorine-containing terminals and interfacial structure. In this study, based on intrinsic Ti3C2Tx, we employed alkali treatment and annealing to prepare oxygen-rich Ti3C2(OH)x/Ti3C2Ox with expanded interlayer spacing, achieving enhanced gas sensing performance for NH3. By utilizing the intercalation effect of layered materials and the synergistic effect of regulating MXene unique surface terminations, the sensing materials prepared have achieved optimization of surface chemistry and structural. Compared to intrinsic Ti3C2Tx, the interlayer spacing of oxygen-rich Ti3C2(OH)x/Ti3C2Ox increased from 9.1 Å to 12.1 Å. The surface terminations of oxygen-rich Ti3C2(OH)x/Ti3C2Ox have been defluorinated and oxygenated. The maximum response value of oxygen-rich Ti3C2(OH)x/Ti3C2Ox to NH3 was 35.66, approximately twice that of the original Ti3C2Tx at an NH3 concentration of 200 ppm. DFT (Density functional theory) calculations and DRIFT (In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy) tests explained the interaction between the surface terminals and NH3, indicating good selectivity and sensitivity of oxygen-rich Ti3C2(OH)x/Ti3C2Ox to NH3. The results of this study demonstrate that the synergistic effects of surface chemistry and structural engineering are crucial for MXene to optimize the electrochemical performance, particularly the gas sensing performance. This provides a feasible approach for the performance optimization of intrinsic MXene materials. © 2024, The Authors. All rights reserved.

关键词： Oxygen

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Navigating the Dual Pathways of Ion Removal in flow-Electrode Capacitive Deionization: Capacitive Trapping vs. Electrodialytic Migration

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SSRN 2025年

作者： Gu, Haibo Hou, Chengsi Mao, Yunfeng Wu, Deli School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science & Engineering Tongji University Shanghai200092 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092 China

By introducing flowing electrodes, FCDI enables desalination through dual mechanisms of electrodialytic and capacitive effects. Clarifying their distinct roles is essential to advance tailored system design and performance enhancement. This work elucidates the antagonistic interplay between capacitive trapping and electrodialytic migration in flow-electrode capacitive deionization (FCDI) through both electrochemical characterization and multiphysics modeling. Experimental analyses reveal that elevated flow rates enhance electrodialytic migration but impair capacitive adsorption. Multivariate parametric studies demonstrate that capacitive dominance prevails at high current densities and low electrolyte concentrations, whereas electrodialytic effects peak under high electrolyte concentration and moderate flow rates. The balance between the effects of electrodialysis (ED) and capacitive deionization (CDI) is greatly impacted by convective mass transfer, which is caused by the electrode flow rate. While higher solid weight percentages in the flow electrode improve the CDI effect by increasing the number of active sites for salt adsorption, increased electrode flow rates maximize the ED effect by encouraging ion transport in the electrolyte. In short words, strategies to promote free ions dispersing in the electrolyte would enhance the electrodialytic contribution, whereas the concentration polarization would benefit the capacitive contribution. This work opens the door for the exploration of upgrading FCDI architectures and optimizing operation parameters while providing insights into the intricate interactions within the system. © 2025, The Authors. All rights reserved.

关键词： Desalination

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Multi-Objective Optimization and Configurations Comparison of Closed-Air Brayton Cycle

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SSRN 2023年

作者： Qian, Yiran Gu, Zhenzhen Song, Meihui Yang, Yi Zhao, Quanbin Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Institute of Atomic Energy P.O. Box 275-32 Beijing102413 China

Microreactor power system has characteristics of efficient, compact and high environmental adaptability. In this study, closed-air Brayton cycle (CABC) is proposed as the microreactor thermoelectric conversion system, and thermodynamic model of CABC with different configurations are established. The cycle parameters and component’s structure are designed using system-component combined design method. To obtained the optimal system design scheme, the Genetic Algorithm (GA) and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) are separately applied for single-objective optimization and multi-objective optimization. According to multi-objective optimization results, the IRRC has the highest cycle efficiency of 35.4% and the ratio of power to mass of 59.1 kW·t-1 , respectively, and the RRC has the highest power density of 179.6 kW·m-3 . Similar performance with IRRC and simpler structure make the RRC the optimal configuration of CABC. Compared with single-objective optimization, the design results of multi-objective optimization are more balanced in terms of three performance indicators, meaning that the optimized design scheme has a better comprehensive performance. © 2023, The Authors. All rights reserved.

关键词： Multiobjective optimization

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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryton Cycle Coaxial Integrated Unit

Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryto...

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Prognostics and System Health Management Conference (PHM-Qingdao)

作者： Xiaokang Xu Yi Yang Jiangfeng Wang Juwei Lou Liangqi Chen State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and Technology National University of Defense Technology Changsha China

The rotor system plays a very important role in supercritical carbon dioxide Brayton cycle system, and its dynamic problem will directly affect the motion stability and safety of the whole unit. In this paper, the rotor dynamic model of supercritical CO 2 coaxial unit is established by finite element method, and the critical speed, modal shape and unbalance response of the rotor are studied. The first seven critical speed of the rotor and the first seven natural frequency of the rotor at the working speed are calculated. The bending modal of the rotor and the position where the rotor amplitude is the largest are analyzed, which can provide reference for the optimization design of the rotor stability. The influences of mass unbalances at the operational speed of rotor are analyzed. The research can provide some suggestions for the optimal design and actual operation of the supercritical CO 2 coaxial integrated unit.

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Performance Prediction and Geometry Optimization of Ejector in Pemfc System Using Coupled Cfd-Bpnn and Genetic Algorithm

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SSRN 2024年

作者： Pang, Zihui Han, Jiquan Feng, Jianmei Diao, Anna Yao, Yanchen Peng, Xueyuan School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Shanghai Marine Diesel Engine Research Institute Shanghai Shanghai201108 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The ejector is a promising hydrogen recirculation device in proton exchange membrane fuel cell (PEMFC) systems. However, the limited entrainment performance of the ejector at wide operating conditions hinders its development and widespread application in PEMFC systems. To address this challenge and design a high-performance ejector adapted to the wide power range of PEMFC systems, a backpropagation artificial neural network (BPNN) model with computational fluid dynamics (CFD) simulation data is developed. The sensitivity analysis of geometric parameters based on the CFD model reveals that the nozzle throat diameter (Dt) and the mixing chamber diameter (Dm) exert the most pronounced impact on the entrainment performance, with average influence rates of 24% and 57%, respectively. Furthermore, two advanced multi-objective genetic algorithms (LWGA and NSGA-II methods) are applied to improve ejector performance. The LWGA method proves effective in elevating the overall ejector performance, achieving a remarkable enhancement in entrainment performance of up to 7.9%. On the other hand, the NSGA-II method is favorable for expanding the operational power range of the ejector by 30%, as well as a 4.5% increase in overall ejector performance. This work provides a robust framework for designing and optimizing high-performance ejectors in high power PEMFC systems. © 2024, The Authors. All rights reserved.

关键词： Sensitivity analysis

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Experimental Study on High-Energy Fluid Jets from a Pipe: Jet Cone Morphology and Impact Force on Flat Plates

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SSRN 2024年

作者： Bi, Qincheng Zhang, Tao Wang, Teng Zhao, Jinle Feng, Fan Liu, Zhaohui State Key Lab Multiphase Flow Power Engn Xi'an Jiaotong University Shaanxi Xian710049 China Department of Power Engineering North China Electric Power University Baoding071003 China

Owing to potential adverse effects such as fatigue, vibration, scouring, and inherent defects, high-pressure pipelines in chemical processes may fail during operation. After failure, high-energy fluid jets into the surrounding space, causing damage to the surrounding equipment and personnel. In extreme cases, the load generated by the jet exerts a reaction force at the pipeline failure point, which causes the pipeline to produce a strong whip, further endangering surrounding systems. To prevent such fundamental and secondary damages, it is important to study the magnitude of the impact force caused by the jetting process and the extent of the impact of the jet cone on surrounding *** this study, an experimental visualization system was utilized that allowed for a continuous and stable heating-jetting-cooling-recovery process for the working fluid. The distance between the nozzle and the impacted target plate can be adjusted on purpose. In this system, deionized water was heated to various conditions (1–8 MPa;20–344 °C) and different states, such as sub-cooled water, two-phase flow, and superheated steam, and then discharged into an atmospheric-pressure environment through pipes of different diameters (2.4–9.2 mm) and length-to-diameter ratios (20–120). Subsequently, the jet cone expanded freely or impacted plates of various sizes and at different distances. Based on the stability and flexibility of this experimental system, new details regarding the jetting process were obtained. Ultimately, a series of experimental data on the jet impact force were obtained, and the expansion morphology of the fluid in the atmospheric-pressure environment was recorded via a high-speed *** experimental results indicate that the water state parameters and the nozzle/pipe structural dimensions significantly affect the shape of the jet cone as well as the magnitude and variation pattern of the jet impact force. Additionally, the jet impact force varies with the distance f

关键词： Atmospheric pressure

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Characteristics of Bubble Dynamic Behavior on the Surface of Photoelectrode Under the Influence of a Vertical Magnetic Field

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SSRN 2023年

作者： Feng, Yuyang Wang, Yechun Zhang, Bo Cao, Zhenshan Liu, Miaomiao Zhen, Canghao Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Xinjin Weihua Institute of Clean Energy Research Nanhai District Guangdong Province Foshan City China

The magnetohydrodynamic (MHD) flow around the bubble induced by the Lorentz force owing to the applied magnetic field significantly affects the behavioral characteristics of the bubble on the electrode surface. However, the mechanism of the impact of a magnetic field perpendicular to the electrode on the dynamic behavior of bubbles remains unclear. In this study, the evolution law of a single oxygen bubble on the surface of a TiO2 photoelectrode under the influence of a vertical magnetic field with different magnetic induction intensities was investigated. The vertical magnetic field effectively promoted the rapid detachment of bubbles from the electrode surface, and greatly improved the gas evolution efficiency. The mass transfer was dominated by single-phase free convection during bubble evolution. Under the influence of the vertical magnetic field, the mass transfer coefficient near the electrode was enhanced, and the adverse effects of bubbles on mass transfer were counteracted when they entered the reaction-controlled growth phase. The further multiphysics simulation found that the MHD convection decreased the local supersaturation of reaction product oxygen molecules near the electrode, thereby reducing concentration overpotential and increasing the reaction rate. This study provides an experimental and theoretical basis for promoting the bubble detachment and the reaction rate on the gas evolving electrode surface during photoelectrochemical water splitting. © 2023, The Authors. All rights reserved.

关键词： Efficiency

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Dynamic simulation of coal-fired power plant integrated with trough solar collector operating in parallel with high pressure heaters

Dynamic simulation of coal-fired power plant integrated with...

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2019 Canadian Society for Civil engineering Annual Conference, CSCE 2019

作者： Yan, Hui Li, Xin Liu, Ming Chong, Daotong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791883747

Solar-aided coal-fired power plant (SACFPP) is a costeffective approach to overcome solar energy intermittency. SACFPPs frequently operate in dynamic processes due to power load and solar energy fluctuations. This study investigated the dynamic characteristics of SACFPPs;such characteristics are important for flexibility evaluation and control system design. The SACFPP used in this study was based on a 660 MW coalfired power plant, and a trough collector system (TCS) operates in parallel with high pressure (HP) heaters. After model development and validation, the dynamic performance of the SACFPP was analyzed under four load ratios of power plant, with disturbances of two parameters: direct normal irradiance (DNI) and mass flowrate ratio to TCS. The performance was also compared with three parallel TCS connection modes. Results showed that the magnitude and response time for power variation under DNI disturbance increased with load ratio. With 500 W/m2 DNI step increments, power increased by approximately 18.4, 21.2, 24.7, and 29.8 MW in 2200, 2330, 2550 and 2620 s at 70%, 80%, 90%, and 100% load ratios, respectively, when all the HP heaters were replaced. The serial number and the number of HP heaters replaced also increased the power variation and response time. Under mass flowrate ratio to TCS increase disturbance, the power rapidly changed to its maximum and then slowly decreased, but the variation value depended on the load ratio. Copyright © 2020 ASME.

关键词： Coal fired power plant

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Recent Progress on Al_(2)O_(3)-C Refractories with Low/ultra-low Carbon Content:A Review

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China's Refractories 2022年第1期31卷 35-44页

作者： ZHAO Chenrui YAN Mingwei LI Hongyu NIU Zhiwang LIANG Baoqing SHANG Junli Henan Rongjin High Temperature Materials Co. Ltd.Weihui 453100China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

This work intends to provide a comprehensive review on the development of Al_(2)O_(3)-C refractories with low/ultra-low carbon *** covers three parts:carbon materials,microstructure optimization of the refractory matrix by ceramic phases,and application of metal Al as raw *** black,expanded graphite,and ultrafine microcrystalline graphite,as price-competitive carbon materials,can be chosen to prepare the low-carbon Al_(2)O_(3)-C refractories after some special ***/Co/Fe-catalyzed phenolic resin contributes to improving the properties of the low-carbon Al_(2)O_(3)-C *** performance deterioration of the low-carbon Al_(2)O_(3)-C refractories can also be improved by in-situ formed or pre-synthesized ceramic *** Al,characterized by plasticity forming,acceleration of sintering,oxidation resistance,and high reactivity,can be used as raw materials to completely replace graphite,and the prepared resin bonded Al-Al_(2)O_(3)based refractories are one novel development direction of the ultra-low carbon Al_(2)O_(3)-C refractories.

关键词： low carbon carbon source alumina-carbon refractories ceramic phases aluminum

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Deterministic Synthesis of Pd Nanocrystals Enclosed by High-Index Facets and Their Enhanced Activity toward Formic Acid Oxidation

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Precision Chemistry 2023年第6期1卷 372-381页

作者： Maochang Liu Siyu Zhou Sang-Il Choi Younan Xia The Wallace H.Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory UniversityAtlantaGeorgia 30332United States International Research Center for Renewable Energy State Key Laboratory of Multiphase FlowXi’an Jiaotong UniversityXi’anShanxi 710049P.R.China School of Chemical and Biomolecular Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332United States School of Chemistry and Biochemistry and School of Chemical and Biomolecular Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332United States

Noble-metal nanocrystals enclosed by high-index facets are of growing interest due to their enhanced catalytic performance in a variety of ***,we report the deterministic synthesis of Pd nanocrystals encased by high-index facets by controlling the rate of deposition(V_(deposition))relative to that of surface diffusion(V_(diffusion)).For octahedral seeds with truncated corners,a reduction rate(and thus deposition rate)faster than that of surface diffusion(i.e.,V_(deposition)/V_(diffusion)>1)led to the formation of concave trisoctahedra(TOH)with high-index *** the reduction was slowed down,in contrast,surface diffusion dominated the growth *** the case of V_(deposition)/V_(diffusion)≈1,truncated octahedra with enlarged sizes were *** the reduction rate was between these two extremes,we obtained concave tetrahexahedra(THH)without or with *** growth patterns were also observed for the cuboctahedral *** the Pd octahedra,concave TOH,and concave THH were tested for electrocatalyzing the formic acid oxidation(FAO)reaction,those with high-index facets were advantageous over the conventional Pd octahedra enclosed by{111}*** work not only contributes to the understanding of surface diffusion and its role in nanocrystal growth but also offers a general protocol for the synthesis of nanocrystals enclosed by high-index facets.

关键词： palladium surface diffusion high-index facet unconventional morphology kinetic control

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