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Thermodynamic and safety analysis for hydrogen production in a supercritical water gasification system of coal by multi-oxidizers distribution

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Energy 2025年 331卷

作者： Kui Luo Runqiu Dong Xujun Li Zhiyong Peng Libo Lu Jialing Xu Hui Jin Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF) Xi'an Jiaotong University NO.28 Xianning West Road Xi'an 710049 Shaanxi Province China Dongfang Steam Turbine Co. Ltd. Deyang 618000 China Jiangxi Provincial Key Laboratory of Particle Technology Jiangxi University of Science and Technology Ganzhou 341000 China School of Smart Energy Shanghai Jiao Tong University Shanghai 201100 China

Coal supercritical water gasification (SCWG) for hydrogen production technology is highly prospective due to the clean and efficient treatment process. A single oxidation reactor heating method is usually used in existing work limiting the efficient and stable operation of the system due to high component temperatures. This paper proposed the heat supply strategy of multi-oxidation reactor and heat exchanger layout to improve the system performance for the realization of reasonable matching of material flow and energy flow in each stage of the system. The improved system reduced the maximum temperature of the oxidation reactor from 1550 °C to 850 °C, and the system exergy efficiency and H 2 yield reached 49.30 % and 101 kg/h (at the mass ratio of coal to water of 1:10), respectively. The exergy flow results showed that the improved system exergy loss was concentrated in the oxidation reactor (34.00 %) heat exchanger (28.86 %), cooler (19.07 %), and gasification reactor (9.70 %). Exergy efficiency increased as the mass ratio of coal to water increased to the maximum exergy efficiency of 53.50 %. As the temperature increased from 600 °C to 675 °C, the exergy efficiency decreased from 53.10 % to 48.70 %. System adjustability analysis showed that the system can be stabilized over a 40 %–100 % range of feed fluctuations. This work may provide an optimization strategy for efficient operation and dynamic safety regulation of H 2 production by SCWG technology.

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Spin-to-orbital angular momentum conversion in non-Hermitian photonic graphene

arXiv

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arXiv 2025年

作者： Zhang, Zhaoyang Kokhanchik, Pavel Liu, Zhenzhi Shen, Yutong Liu, Fu Liu, Maochang Zhang, Yanpeng Xiao, Min Malpuech, Guillaume Solnyshkov, Dmitry Key Laboratory for Physical Electronics and Devices Ministry of Education Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information Xi’an Jiaotong University Xi’an710049 China Institut Pascal PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP Clermont-FerrandF-63000 France International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China National Laboratory of Solid State Microstructures School of Physics Nanjing University Nanjing210093 China Paris75231 France

Optical beams with orbital angular momentum (OAM) have numerous potential applications, but the means used for their generation often lack crucial on-demand control. In this work, we present a mechanism of converting spin angular momentum (SAM) to OAM in a non-structured beam. The conversion occurs through spin-orbit coupling in a reconfigurable photonic honeycomb lattice with staggering implemented by electromagnetically-induced transparency in an atomic vapor cell. The spin-orbit coupling allows to outcouple the OAM signal from a particular band in a given valley determined by the chirality of light or the lattice staggering, providing a non-zero Berry curvature for generating OAM. The dependence of the output OAM on the chirality of the input beam is the first control knob. The staggering works as a second control knob, flipping the sign of OAM for the fixed chirality. The demonstrated conversion between SAM and OAM is important for optical communications. Our results can be extended to other implementations of paraxial photonic graphene. Copyright © 2025, The Authors. All rights reserved.

关键词： Angular momentum

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Flocculation of suspended cohesive particles in homogeneous isotropic turbulence

arXiv

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arXiv 2021年

作者： Zhao, K. Pomes, F. Vowinckel, Bernhard Hsu, T.-J. Bai, B. Meiburg, E. Department of Mechanical Engineering UC Santa Barbara Santa BarbaraCA93106 United States State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Leichtweiß-Institute for Hydraulic Engineering and Water Resources Technische Universität Braunschweig Braunschweig38106 Germany Center for Applied Coastal Research Department of Civil & Environmental Engineering University of Delaware NewarkDE19716 United States

We investigate the dynamics of cohesive particles in homogeneous isotropic turbulence, based on one-way coupled simulations that include Stokes drag, lubrication, cohesive and direct contact forces. We observe a transient flocculation phase characterized by a growing average floc size, followed by a statistically steady equilibrium phase. We analyze the temporal evolution of floc size and shape due to aggregation, breakage, and deformation. Larger turbulent shear and weaker cohesive forces yield elongated flocs that are smaller in size. Flocculation proceeds most rapidly when the fluid and particle time scales are balanced and a suitably defined Stokes number is O(1). During the transient stage, cohesive forces of intermediate strength produce flocs of the largest size, as they are strong enough to cause aggregation, but not so strong as to pull the floc into a compact shape. Small Stokes numbers and weak turbulence delay the onset of the equilibrium stage. During equilibrium, stronger cohesive forces yield flocs of larger size. The equilibrium floc size distribution exhibits a preferred size that depends on the cohesive number. We observe that flocs are generally elongated by turbulent stresses before breakage. Flocs of size close to the Kolmogorov length scale preferentially align themselves with the intermediate strain direction and the vorticity vector. Flocs of smaller size tend to align themselves with the extensional strain direction. More generally, flocs are aligned with the strongest Lagrangian stretching direction. The Kolmogorov scale is seen to limit floc growth. We propose a new flocculation model with a variable fractal dimension that predicts the temporal evolution of the floc size and shape. © 2021, CC BY.

关键词： Flocculation

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Correction to: Modification of a first‑generation solid oxide fuel cell cathode with Co3O4 nanocubes having selectively exposed crystal planes

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Materials for Renewable and Sustainable Energy 2022年第3期11卷 299-299页

作者： Xu, Xi Wang, Chao Fronzi, Marco Liu, Xuehua Bi, Lei Institute of Materials for Energy and Environment College of Materials Science and Engineering Qingdao University Qingdao China State Key Laboratory of Multiphase Flow in Power Engineering International Research Centre for Renewable Energy Xi’an Jiaotong University Xi’an China

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Electrochemical oxidation of rhodamine B by PbO_2/Sb-SnO_2/TiO_2 nanotube arrays electrode

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Chinese Journal of Catalysis 2019年第6期40卷 917-927页

作者： Jia Wu Kai Zhu Hao Xu Wei Yan Xi’an XD Switchgear Electric Co. Ltd.Xi’an 710049ShaanxiChina Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina

A PbO2/Sb-SnO2/TiO2 nanotube array composite electrode was successfully synthesized and its electrochemical oxidation properties were ***-emission scanning electron microscopy(FE-SEM)and X-ray diffraction(XRD)results showed that the PbO2 coating was composed of anα-PbO2 inner layer and aβ-PbO2 outer *** life measurement indicated that the composite electrode had a lifetime of 815 *** B(RhB)was employed as a model pollutant to analyze the electrocatalytic activity of the *** effects of initial RhB concentration,current density,initial pH,temperature,and chloride ion concentration on the electrochemical oxidation were investigated in *** coupled plasma atomic emission spectroscopy(ICP-AES)results suggested that the concentration of leached Pb^2+in the electrolyte during the electrocatalytic oxidation process can be ***,the degradation mechanism during the electrocatalytic oxidation process was proposed based on the results of solid-phase micro-extraction-gas chromatography-mass spectrometry(SPME-GC-MS).The high electrocatalytic performance of the composite electrode makes it a promising anode for the treatment of organic pollutants in aqueous solution.

关键词： TiO2 nanotube array Electrochemical oxidation Rhodamine B Degradation mechanism

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Tailoring Second Coordination Sphere for Tunable Solid–Liquid Interfacial Charge Transfer toward Enhanced Photoelectrochemical H2Production

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Angewandte Chemie 2024年第22期136卷

作者： Dr. Yangguang Hu Dr. Wu Zhou Dr. Wanbing Gong Prof. Chao Gao Prof. Shaohua Shen Prof. Tingting Kong Prof. Yujie Xiong Anhui Engineering Research Center of Carbon Neutrality The Key Laboratory of Functional Molecular Solids Ministry of Education College of Chemistry and Materials Science Anhui Normal University 241002 Wuhu Anhui China Hefei National Laboratory for Physical Sciences at the Microscale School of Chemistry and Materials Science University of Science and Technology of China 230026 Hefei Anhui China These authors equally contributed to this work International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an Shaanxi China

The recombination of photogenerated charge carriers severely limits the performance of photoelectrochemical (PEC) H 2 production. Here, we demonstrate that this limitation can be overcome by optimizing the charge transfer dynamics at the solid–liquid interface via molecular catalyst design. Specifically, the surface of a p-Si photocathode is modulated using molecular catalysts with different metal atoms and organic ligands to improve H 2 production performance. Co(pda-SO 3 H) 2 is identified as an efficient and durable catalyst for H 2 production through the rational design of metal centers and first/second coordination spheres. The modulation with Co(pda-SO 3 H) 2 , which contains an electron-withdrawing −SO 3 H group in the second coordination sphere, elevates the flat-band potential of the polished p-Si photocathode and nanoporous p-Si photocathode by 81 mV and 124 mV, respectively, leading to the maximized energy band bending and the minimized interfacial carrier transport resistance. Consequently, both the two photocathodes achieve the Faradaic efficiency of more than 95 % for H 2 production, which is well maintained during 18 h and 21 h reaction, respectively. This work highlights that the band-edge engineering by molecular catalysts could be an important design consideration for semiconductor–catalyst hybrids toward PEC H 2 production.

关键词： PEC H2 production molecular catalyst coordination sphere surface modulation charge transfer

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Error Analysis of Liquid Holdup Measurement in Gas-Liquid Annular Flow Through Circular Pipes Using High-Speed Camera Method

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Journal of Shanghai Jiaotong university(Science) 2018年第S1期23卷 34-40页

作者： LIU Li BAI Bofeng School of Nuclear Science and Engineering Shanghai Jiao Tong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Accurate measurement of gas-liquid phase fraction is essential for the proper modelling of the pressure drop, heat transfer coefficient, mass transfer rate and interfacial area in two-phase flows. In this paper, taking the issue of optical distortion into account, an analytical model was proposed to estimate and correct the liquid holdup in gas-liquid annular flow through a circular pipe using high-speed camera method. The error in the liquid holdup measurement generated from different refractive indices among transparent circular pipe, liquid film and air core was firstly theoretically analyzed based on the geometric optics. Experimental tests were then carried out to identify the difference as well as to validate the proposed model. Results indicated that the prediction of the liquid holdup has a good performance with the experimental data(i.e., mean relative error is 4.1%) and the measured liquid holdup is larger than the real one. It was found that the measured liquid holdup is larger than the real one. Generally, when the real liquid holdup gets smaller, the discrepancy between the measured liquid holdup by image and the real liquid holdup becomes more significant. Thus, after measuring the liquid holdup from the images, the value of the measured liquid holdup must be corrected by the present model in order to obtain the real liquid holdup.

关键词： gas-liquid annular flow liquid holdup optical refraction analytical correction

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Enhanced efficiency in Concentrated Parabolic Solar Collector(CPSC) with a porous absorber tube filled with metal nanoparticle suspension

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Green Energy & Environment 2018年第2期3卷 129-137页

作者： Mohammad Hatami Jiafeng Geng Dengwei Jing Mechanical Engineering Department Esfarayen University of Technology (EUT) International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

In this study, effects of different nanoparticles and porosity of absorber tube on the performance of a Concentrating Parabolic Solar Collector(CPSC) were investigated. A section of porous-filled absorber tube was modeled as a semi-circular cavity under the solar radiation which is filled by nanofluids and the governing equations were solved by FlexPDE numerical software. The effect of four physical parameters, nanoparticles type, nanoparticles volume fraction(φ), Darcy number(Da) and Rayleigh number(Ra), on the Nusselt number(Nu) was discussed. It turns out that Cu nanoparticle is the most suitable one for such solar collectors, compared to the commonly used Fe_3O_4, Al_2O_3, TiO_*** the increased addition of Cu nanoparticles all the parameters φ, Da and Ra shows a significant increase against the Nu, indicates the enhanced heat transfer in such cases. As a result, low concentration of Cu nanoparticle suspension combined with porous matrix was supposed to be beneficial for the performance enhancement of concentrating parabolic solar collector.

关键词： Concentrating parabolic solar collector Porous absorber tube Nanofluid Nusselt number Finite Element Method

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The mechanism of enhancement or deterioration for nanofluid flow boiling based on the experimental results 27

The mechanism of enhancement or deterioration for nanofluid ...

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27th International Conference on Nuclear engineering: Nuclear power Saves the World!, ICONE 2019

作者： Wang, Y. Wu, J.M. Zan, Y.F. Qiu, S.Z. Deng, K.H. Yue, N.N. Su, G.H. CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China State Key Labortatory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xianning West Road 28# Xi'an710049 China School of Aerospace State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University Xianning West road 28# Xi'an710049 China School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West road 28# Xi'an710049 China

ISBN: (纸本)9784888983051

Nanofluid is a potential working fluid for new heat transfer technology. However, the investigation on its ability of flow boiling heat transfer is really scarce. Papers focused on nanolfuid flow boiling is much less than it pool boiling. In addition, the flow boiling heat transfer is enhanced or deteriorated has been extremely controversial for over ten years. In present work, an experimental set up is designed and carried out. Moreover, the flow boiling heat transfer of nanofluid is experimental studied with the consideration of working conditions and nanofluid types. The results indicate that both the enhancement and deterioration of nanofluid flow boiling are discovered. Moreover, the flow boiling heat transfer of nanofluid which is composed of non-metallic compound nanoparticles are deteriorated under most working conditions. What's more important is that it is deteriorated under lower pressure and enhanced under higher pressure for the same kind of nanofluid like SiC/H2O and Graphite/H2O. After all, the phenomena are explained and a mechanism is proposed of nanofluid flow boiling enhancement or deterioration based on the experimental results. Copyright © 2018-2019 by JSME

关键词： Deterioration

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Au [email protected] @ZnIn 2 S 4 nanosheets with significantly enhanced visible-light photocatalytic H 2 evolution: The effect of different Au positions on the transfer of electron-hole pairs

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Applied Catalysis B: Environmental 2021年 282卷

作者： Siman Mao Jian-Wen Shi Guotai Sun Dandan Ma Chi He Zengxin Pu Kunli Song Yonghong Cheng State Key Laboratory of Electrical Insulation and Power Equipment Center of Nanomaterials for Renewable Energy School of Electrical Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

Herein, a new type of photocatalysts, Au [email protected] @ZnIn 2 S 4 nanosheets ( [email protected] @ZIS), is elaborately designed for the photocatalytic H 2 evolution from water splitting, where Au nanodots (NDs) are anchored in the pore space of thiol-functionalized UiO66 metal-organic framework (MOF) and ZnIn 2 S 4 nanosheets are wrapped around the UiO66 MOF containing Au NDs. It is found that the different Au positions have a grateful effect on the transfer of photogenerated charge carriers. In [email protected] @ZIS, the photoexcited electrons transfers from ZnIn 2 S 4 to UiOS and then to Au NDs, establishing a smooth transmission channel of electrons. As expected, the optimal sample (Au 4 @ [email protected] 40 ) presents a high photocatalytic H 2 production rate of 391.6 μmol/h (10 mg of catalyst) under visible light irradiation, which is 435.1, 61.2 and 10.2 times higher than that of the pure UiOS, ZnIn 2 S 4 and [email protected] , respectively.

关键词： Photocatalysis Hydrogen evolution Metal-organic framework Thiol- functionalization Au nanodots

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