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Experimental and Theoretical Study on CHF of a Ultra-Supercritical Circulating Fluidized Bed Boiler Water-Wall Tube at near-Critical Pressures

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Journal of Thermal Science 2023年第1期32卷 166-182页

作者： WANG Wenyu MA Zhan QING Hao NIE Chao YANG Haoyu BI Lingfeng YANG Dong PAN Wenxiao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China Department of Mechanical Engineering University of Wisconsin-Madison1513 University AveMadisonWI 53706USA

The experimental and theoretical research on the critical heat flux(CHF)in a uniformly heated water-wall tube of the efficient ultra-supercritical circulating fluidized bed(USCFB)boiler has been *** particular,the experimental pressure varies from 18 MPa to 21 MPa,which is from 0.814Pcr–0.95Pcr(Pcr:critical pressure).The mass flux varies from 310 kg·m^(–2)·s^(–1)to 550 kg·m^(–2)·s^(–1).The inlet sub-cooling temperatures vary from 5°C to 10°*** material of the tube is *** experimental investigation,the near critical pressure CHF test data of water are *** find that the CHF mainly occurs when the vapor qualities are less than 0.4,and it occurs earlier(at lower vapor quality)when the pressure is closer to 22.115 MPa or the mass flux is *** the experimental data,a correlation function for the CHF is established via regression and machine *** established via machine learning greatly improved the regression *** study the CHF phenomenon mechanically,a theoretical model is established based on the near-surface bubble crowding model describing the DNB-type *** the development of the CHF model,the friction resistance coefficient is determined according to our test *** comparison with different experimental results,the near-surface bubble crowding model is well suited to describe DNB-type *** calculation results of the model can provide reference for the optimal design of the USCFB boiler.

关键词： circulating fluidized bed critical heat flux near-critical pressure bubble crowding machine learning

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MIXED DISCONTINUOUS GALERKIN METHOD FOR QUASI-NEWTONIAN STOKES flowS

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Journal of Computational Mathematics 2024年第3期42卷 885-910页

作者： Yanxia Qian Fei Wang Wenjing Yan School of Mathematics and Statistics Xi'an Jiaotong UniversityXi'an 710049China School of Mathematics and Statistics&State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In this paper,we introduce and analyze an augmented mixed discontinuous Galerkin(MDG)method for a class of quasi-Newtonian Stokes *** the mixed formulation,the unknowns are strain rate,stress and velocity,which are approximated by a discontinuous piecewise polynomial triplet ■for k≥***,the discontinuous piecewise polynomial function spaces for the field of strain rate and the stress field are designed to be *** addition,the pressure is easily recovered through simple *** the benefit of the analysis,we enrich the MDG scheme with the constitutive equation relating the stress and the strain rate,so that the well-posedness of the augmented formulation is obtained by a nonlinear functional *** k≥0,we get the optimal convergence order for the stress in broken ■(div)-norm and velocity in L^(2)-***,the error estimates of the strain rate and the stress in-norm,and the pressure in L^(2)-norm are optimal under certain ***,several numerical examples are given to show the performance of the augmented MDG method and verify the theoretical *** evidence is provided to show that the orders of convergence are sharp.

关键词： Quasi-Newtonian fows Mixed discontinuous Galerkin method Symmetric strain rate Symmetric stress Optimal convergence orders

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Experimental study on the thermochemical reduction of supercritical CO2by guaiacol 8

Experimental study on the thermochemical reduction of superc...

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8th International Conference on Smart and Sustainable Technologies, SpliTech 2023

作者： Wei, Yimeng Kuanibieke, Jiadela Jin, Hui Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering China

ISBN: (纸本)9789532901283

The continuous growth of CO2 emissions is one of the global problems facing humanity, and how to convert and exploit the stock of CO2 has become an urgent issue. Biomass as an activity of CO2 thermal reduction medium has become the focus of human attention in general. Supercritical CO2 (SCCO2) has the advantages of near-liquid density and high solubility, which can further strengthen the reduction process (T≥31.26, P≥72.9 atm). This paper described a SCCO2 reduction method of guaiacol on an intermittent Kettle Reactor to investigate the effects of reaction temperature (400-700), residence time (5-20 min) and reactant concentration (4 wt%-16wt%) on the three-phase products. The experimental results indicated that the carbon gasification efficiency (CE) and hydrogen gasification efficiency (HE) were 43.7% and 56.7%, respectively, when the carbon dioxide consumption reached 16.15 mol/kg. As the temperature increased, the consumption of carbon dioxide increased and the concentration of reactants increased with opposite results. © 2023 University of Split, FESB.

关键词： Carbon dioxide

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Reconstruction of particle distribution for tomographic particle image velocimetry based on unsupervised learning method

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Particuology 2024年第10期93卷 349-363页

作者： Duanyu Zhang Haoqin Huang Wu Zhou Mingjun Feng Dapeng Zhang Limin Gao School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering University of Shanghai for Science and TechnologyShanghai200093China National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an710072China

The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density.

关键词： Tomographic particle image velocimetry 3D reconstruction Unsupervised learning Convolutional neural network

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Lattice-mismatch-induced formation of defect-rich Pd-Cu alloy nanocages for enhanced formic acid oxidation activity

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Science China Chemistry 2025年第2期68卷 481-491页

作者： Zhaojun Liu Zhengyan Wang Zhaoyu Wang Hao Yuan Yuke Bai Xiaoxiao Wang Zerui Mu Chunxia Wu Kai Liu Zhun Hu Chuanbo Gao Sate Key Laboratory of Multiphase Flow in Power Engineering Frontier Institute of Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Institute of Industrial Catalysis School of Chemical Engineering and TechnologyXi’an Jiaotong UniversityXi’an 710049China

Crystallographic defects in noble metal nanocrystals are recognized as highly active catalytic sites,significantly enhancing activities in many important *** their importance,synthesizing noble metal nanocrystals with a high density of defects poses a considerable synthetic ***,we present a novel lattice mismatch-induced formation mechanism to create high-density defects in noble metal *** approach takes advantage of lattice mismatch to enable nonepitaxial nucleation and growth of a noble metal on a foreign metal substrate,forming abundant noble metal crystallites with random lattice orientations not dictated by the substrate *** these crystallites grow extensively,they merge,forming numerous grain boundaries and yielding defect-rich noble metal ***-rich alloy nanocrystals can also be synthesized through a subsequent vacancy-diffusion alloying *** take defective PdCu alloy nanocages as an example and demonstrate the effectiveness of crystallographic defects in enhancing catalytic performance of noble metal *** nanocages exhibit superior activity in the electrocatalytic formic acid oxidation reaction,which is 1.6 times greater than their defect-free *** strategy offers a new avenue for creating defect-rich noble metal nanocrystals as highly efficient catalysts for a wide array of catalytic applications.

关键词： noble metal nanocrystals defects non-epitaxial growth electrocatalysis formic acid oxidation reaction

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Honeycomb-like biochar framework coupled with Fe_(3)O_(4)/FeS nanoparticles as efficient heterogeneous Fenton catalyst for phenol degradation

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Journal of Environmental Sciences 2024年第2期136卷 390-399页

作者： Aihua Cheng Yi He Xiaohe Liu Chi He Department of Environmental Engineering College of Geology and EnvironmentXi’an University of Science and TechnologyXi’an 710054China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China National Engineering Laboratory for VOCs Pollution Control Material and Technology University of Chinese Academy of SciencesBeijing 101408China

Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater ***,a pollen-derived biochar catalyst with a unique honeycomb-like structure,coupled with the dispersion of magnetic Fe_(3)O_(4)/FeS(Fe/S)nanoparticles,was synthesized by simple impregnation precursor,followed by *** prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range,with 98%of which eliminated even under neutral conditions(pH 7.0).The high catalytic activity was due to the multilevel porous structure of pollenderived biochar provided enough active sites and allowed for better electron transfer,then increases oxidation ability to promote the ***,the acid microenvironment formed by SO_(4)^(2-)group from Fe/S composite extended the pH range for Fenton reaction,and S^(2-)facilitated the conversion of≡Fe^(3+)to≡Fe^(2+),resulting in remarkable degradation ***,biochar can effectively promote cycling stability by limiting Fe *** work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.

关键词： Biomass Biochar Fenton reaction Fe_(3)O_(4)/FeS(Fe/S) Phenol degradation

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BiOI晶体缺陷工程提升光催化CO2到C2产物转化性能（英文）

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Science China Materials 2025年第5期68卷 1561-1569页

作者：黄富霞刘一菲王峰刘亚郭烈锦 International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

BiOI材料在光催化CO2还原领域展现出巨大潜力,但其较弱的CO2的活化能力与较差的载流子分离效率严重制约了光催化转化效率.本研究通过构建富含丰富晶体缺陷的BiOI基光催化剂有效地提高了其光催化性能.结合X射线衍射、拉曼、和高分辨透射... 详细信息

BiOI材料在光催化CO2还原领域展现出巨大潜力,但其较弱的CO2的活化能力与较差的载流子分离效率严重制约了光催化转化效率.本研究通过构建富含丰富晶体缺陷的BiOI基光催化剂有效地提高了其光催化性能.结合X射线衍射、拉曼、和高分辨透射电子显微镜表征,证实了BiOI-LD和BiOI-TC催化剂中分别存在晶格畸变和孪晶结构缺陷.紫外-可见光谱、微孔与化学吸附分析,以及光致发光光谱表征结果表明,晶体缺陷的引入显著增强了光催化剂的光吸收能力、CO2吸附能力、载流子传输效率及寿命.电子顺磁共振光谱进一步证实BiOI-TC中超氧自由基的生成量显著提升,表明晶体缺陷构筑有效增强了催化剂表面反应活性.因此, BiOI-TC催化剂实现了6.2μmol g-1h-1的CH3CH2OH生成速率,且选择性达到100%.通过原位FTIR研究识别了生成CH3CH2OH的关键中间体（*CO、*COCO、*CHO和*CH2）,并揭示BiOI-LD中C2H6的生成与*CH3中间体的形成密切相关.

关键词： photocatalysis CO2 reduction BiOI crystal defects CH3CH2OH C2H6

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Thermal physical applications of carbon dioxide:Recent progress,challenges and perspective

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Resources Chemicals and Materials 2023年第4期2卷 288-311页

作者： Pei Duan Kun Jiang Jinwen Shi Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityShaanxi710049PR China

Carbon dioxide(CO_(2))is one of the main factors contributing to the greenhouse *** dependence on fossil fuels has led to increasing levels of carbon dioxide in the atmosphere every *** it is far from enough to solve the climate problem by reducing the consumption of fossil fuels to cut down carbon dioxide *** recent years,a series of researches on Carbon Capture,Utilization and Storage(CCUS)have been carried out in various countries around the ***_(2) is a nontoxic,tasteless and stable gas at normal ***,when it reaches supercritical state after rising temperature and pressure,it has the characteristics of low viscosity,high diffusivity and high density,and is widely used in green,pollution-free and efficient development *** of these unique properties,supercritical carbon dioxide(sCO_(2))has attracted more and more attention from ***_(2) has been widely used in many aspects by virtue of its high solubility and easy *** from previous reviews which only introduced the application of sCO_(2) property,this paper introduces the current research status of the application of the thermodynamic property of carbon dioxide in extraction,dyeing,pharmaceutical,power generation,heat transfer and exploitation of unconventional oil and gas,and mainly analyzes each application in detail from the aspects of working mechanism and improving working ***,the research direction and problems needed to be solved for the application of CO_(2) thermal physics are proposed,which pave the way for other new applications.

关键词： Utilization of CO_(2) Supercritical state Thermal physical applications Extraction Heat transfer Oil and gas exploitation

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Defect-engineered WO_(x)/ZnIn_(2)S_(4)Z-scheme heterojunction boosting photocatalytic H_(2)production via photothermal coupling

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Journal of Energy Chemistry 2025年第4期103卷 9-18页

作者： Biao Wang Chunyang Zhang Shidong Zhao Shujian Wang Feng Liu Kejian Lu Yitao Si Maochang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189JiangsuChina Suzhou Academy of Xi’an Jiaotong University Suzhou 215123JiangsuChina

Recent interest in photocatalytic water splitting has intensified the demand in the development of photocatalysts capable of harnessing the full *** study introduces a novel WO_(x)/ZnIn_(2)S_(4)Zscheme heterojunction,prepared by depositing ZnIn_(2)S_(4)(ZIS)nanosheets onto WO_(x)nanorods,enabling efficient photothermal-coupled photocatalytic H_(2)*** success relies on the engineered oxygen vacancies within WO_(x)nanorods,which not only confer excellent photothermal properties lowering the reaction barrier but also create defect levels in WO_(x)facilitating Z-scheme electron transfer from these levels to the valence band of ***,the optimized WO_(x)/ZIS heterojunction exhibits a remarkable H_(2)evolution rate of 33.91 mmol h^(-1)g^(-1)with an apparent quantum efficiency of 23.6%at 400 *** study provides a new strategy for developing efficient Z-scheme heterojunctions with broadspectrum solar hydrogen production capabilities.

关键词： Defect-engineered Z-scheme heterojunction Photocatalytic H2evolution Photothermal coupling

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Multi-objective optimization research of open and closed air brayton cycle

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International Journal of Advanced Nuclear Reactor Design and Technology 2024年第1期6卷 21-31页

作者： Song, Meihui Qian, Yiran Leng, Yuyang Liu, Tao Yu, Lianyun Chen, Weixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Reactor Engineering Technology Research Institute China Institute of Atomic Energy Beijing102413 China

Air Brayton cycle obtains the significant advantages of high efficiency, compact structure, easy medium requirement and so on, which is one of the most suitable choices for the mobile nuclear power conversion system. In this paper, system-component combined design method is used to establish the open and closed air Brayton cycle of diverse configurations. Based on performance and compactness targets, the multi-objective optimization is carried out to find the optimal design by nondominated sorting genetic algorithm II and entropy weight method. According to the analysis, the closed intercooling reheating recuperating cycle is the configuration with the best comprehensive performance, with cycle efficiency of 33.58 %, power density of 175.39 kW m−3 and power mass ratio of 68.60 kW t−1. The open simple recuperating cycle is the configuration with the smallest volume and mass, with cycle efficiency of 20.01 %, system volume of 6.56 m3 and system mass of 19.98 t. The closed intercooling recuperating cycle is the most balanced configuration, with cycle efficiency of 31.33 %, volume of 9.06 m3 and system mass of 24.97 t. Based on the optimal results, off-design performance analysis of different environmental conditions is also carried out for the configurations above. © 2024 Xi'an Jiaotong University

关键词： Brayton cycle

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