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Particle convective heat transfer near the wall in a supercritical water fluidized bed by single particle model coupled with CFD-DEM

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Particuology 2023年第2期73卷 47-58页

作者： Tianning Zhang Zhen Wan Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Electronic Engineering Research Institute Xi'an710100ShaanxiChina

Supercritical water fluidized bed(SCWFB)is a promising reactor to gasify biomass or *** optimization design is closely related to wall-to-bed heat transfer,where particle convective heat transfer plays an important *** paper evaluates the particle convective heat transfer coefficient(h_(pc))at the wall in SCWFB using the single particle *** critical parameters in the single particle model which is difficult to get experimentally are obtained by the computational fluid dynamics-discrete element method(CFD-DEM).The contact statistics related to particle-to-wall heat transfer,such as contact number and contact distance,are also *** results show that particle residence time(τ),as the key parameter to evaluate h_(pc),is found to decrease with rising velocity,while increase with larger thermal boundary layer thickness.τfollows a gamma function initially adopted in the gas-solid fluidized bed,making it possible to evaluate h_(pc) in SCWFB by a simplified single particle *** theoretical predicted h_(pc) tends to increase with rising thermal gradient thickness at a lower velocity(1.5 U_(mf)),while first decreases and then increases at higher velocity(1.75 and 2 U_(mf)).h_(pc) occupies 30%-57%of the overall wall-to-bed heat transfer coefficient for a particle diameter of 0.25 *** results are helpful to predict the overall wall-to-bed heat transfer coefficient in SCWFB combined with a reasonable fluid convective heat transfer model from a theoretical perspective.

关键词： Supercritical water Fluidized bed Particle residence time Discrete element method Single particle model

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Numerical prediction of spatio-temporal frosting patterns of curved surface considering varying working parameters

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Energy Storage and Saving 2023年第1期2卷 348-358页

作者： Xue Liu Xiaojun Dong Shaohang Yan Yu Hou Tianwei Lai State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China

Accurate numerical prediction of frosting patterns is essential for the efficient layout and timing defrosting of heat exchangers under frosting *** this study,a numerical model is developed to predict the spatio-temporal frosting habits on curved surfaces in combination with the correlations of frost density and thermal *** the model,frost melting is *** verification,the frosting and heat transfer characteristics along the flow path are investigated under various structural and operating *** thickness along the path is mainly affected by the cooling surface temperature,while the heat and mass transfer rates are strongly correlated with the humidity *** proportions of latent heat and sensible heat are distributed more unevenly in parallel flow case than in counter flow *** deposition is facilitated by a smaller radius of curvature of the cooling *** uniform frosting characteristics along the path and smaller heat transfer obstruction are presented with a smaller length-to-height ratio of the flow path.

关键词： Frosting Numerical prediction Heat transfer Curved surface Varying parameter

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Alloy nanocrystals:Synthesis paradigms and implications

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Chinese Journal of Structural Chemistry 2023年第11期42卷 1-5页

作者： Zhaojun Liu Zerui Mu Chuanbo Gao State Key Laboratory of Multiphase Flow in Power Engineering Frontier Institute of Science and TechnologyXi'an Jiaotong UniversityXi'an710054China

*** Noble metal nanocrystals serve as exceptional catalysts across a wide spectrum of industrial processes[1].Moreover,there exists a substantial demand for noble metal catalysts in emerging clean-energy applications,such as water-splitting hydrogen production and fuel *** non-noble transition metals or main-group metals into noble metal nanocrystals can reduce the weight of noble metals in the catalysts,thus remarkably lowering the ***,alloy nanocrystals offer intriguing catalytic properties that surpass those of their monometallic counterparts,thanks to the charge transfer between the constituent components and the expansion or shrinkage of the lattice size[2].

关键词： alloy metals noble

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Electrospinning engineering of gas electrodes for high-performance lithium-gas batteries

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Carbon Energy 2024年第10期6卷 353-398页

作者： Jingzhao Wang Xin Chen Jianan Wang Xiangming Cui Ze Wang Guangpeng Zhang Wei Lyu Maxim Shkunov S.Ravi P.Silva Yaozu Liao Kai Yang Wei Yan State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and EngineeringSchool of Energy and Power EngineeringXi'an Jiaotong UniversityXi'anChina Advanced Technology Institute University of SurreyGuildfordSurreyUK State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghaiChina

Lithium-gas batteries(LGBs)have garnered significant attention due to their impressive high-energy densities and unique gas conversion ***,the practical application of LGBs faces substantial challenges,including sluggish gas conversion kinetics inducing in low-rate performance and high overpotential,along with limited electrochemical reversibility leading to poor cycle *** imperative task is to develop gas electrodes with remarkable catalytic activity,abundant active sites,and exceptional electrochemical ***,a versatile and well-established technique for fabricating fibrous nanomaterials,has been extensively explored in LGB *** this work,we emphasize the critical structure-property for ideal gas electrodes and summarize the advancement of employing electrospun nanofibers(NFs)for performance enhancement in *** elucidating the fundamental principles of LGBs and the electrospinning technique,we focus on the systematic design of electrospun NF-based gas electrodes regarding optimal structural fabrication,catalyst handling and activation,and catalytic site optimization,as well as considerations for large-scale *** demonstrated principles and regulations for electrode design are expected to inspire broad applications in catalyst-based energy applications.

关键词： carbon nanofibers electrocatalyst electrospinning gas electrodes metal-gas batteries

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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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Function-reversible facets enabling SrTiO_(3)nanocrystals for improved photocatalytic hydrogen evolution

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Frontiers in Energy 2024年第1期18卷 101-109页

作者： Bin WANG Bei AN Xiaoqian LI Shaohua SHEN School of Physics Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter(Ministry of Education)Key Laboratory of Shaanxi for Advanced Materials and Mesoscopic PhysicsXi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

It has been widely reported that,for faceted nanocrystals,the two adjacent facets with different band levels contribute to promoted charge separation,and provide active sites for photocatalytic reduction and oxidation reaction,*** such cases,only one family of facets can be used for photocatalytic hydrogen ***,by using SrTiO_(3)nanocrystals enclosed by{023}and{001}facets as a model photocatalyst,this paper proposed a strategy to achieve the full-facets-utilization of the nanocrystals for photocatalytic hydrogen via chemically depositing Pt nanoparticles on all *** photo-deposition experiment of CdS provided direct evidence to demonstrate that the{023}facets which were responsible for photooxidation reaction can be function-reversed for photocatalytic hydrogen evolution after depositing Pt nanoparticles,together with the{001}***,the full-facets-utilization led to a much-improved activity for photocatalytic hydrogen,in contrast to those SrTiO_(3)nanocrystals with only{001}facets deposited by Pt nanoparticles via a photo-deposition method.

关键词： SrTiO_(3)nanocrystals crystal facets photocatalysis hydrogen evolution

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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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Experimental study on flow excursion instability of supercritical hydrocarbon fuel in scramjet regenerative cooling parallel channels

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Chinese Journal of Aeronautics 2023年第1期36卷 201-215页

作者： Xiaoyong LIU Zhuqiang YANG Ruipu MIAO Feng LIU Shujun ZHAO Qincheng BI Beijing Power Machinery Research Institute Beijing 100074China Liaoning Key Laboratory of Complex Energy Conversion and Utilization School of Energy and Power EngineeringDalian University of TechnologyDalian 116024China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally studied for supercritical fluids. Two types of flow excursion occur in a single tube. Type Ⅰ and Type Ⅱ excursions, and they are corresponding to decreasing and increasing flow rate respectively. They can trigger flow maldistribution between parallel tubes and the hysteresis phenomenon of flow distribution. The effects of system parameters, including inlet temperature,system pressure, and heat flux, on flow distribution were analyzed. In addition, the relationship between flow excursion and the pseudo-critical interval proposed in the literature was established according to the heated tube outlet temperature at the onset of flow instability. Finally, the flow excursion instability boundary was obtained using two dimensionless parameters. These experimental results can provide helpful insight on the mechanism of Scramjet regenerative cooling.

关键词： flow distribution Ledinegg instability Onset of flow excursion Parallel channels Regenerative cooling Scramjet Supercritical flow

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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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