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Regulation on polymerization degree and surface feature in graphitic carbon nitride towards efficient photocatalytic H2 evolution under visible-light irradiation

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Journal of Materials Science & Technology 2022年第3期98卷 160-168页

作者： Cheng Cheng Chung-Li Dong Jinwen Shi Liuhao Mao Yu-Cheng Huang Xing Kang Shichao Zong Shaohua Shen International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power Engineering(MFPE)Xi'an Jiaotong University(XJTU)28 West Xianning RoadXi’an 710049China Department of Physics Tamkang University151 Yingzhuan RoadTamsui 25137TaiwanChina

A kind of graphitic carbon nitride(TSC-550) with high polymerization degree and improved surface property was prepared by a new precursor of thiosemicarbazide. The sulfur motif and high nitrogen content in thiosemicarbazide promoted the polymerization of thiosemicarbazide to form graphitic carbon nitride framework with high degree of polymerization, which significantly influenced the electronic structure and surface chemical properties. TSC-550 possessed a narrow bandgap of 2.19 eV that facilitated the utilization of visible light, and possessed a less positive charge, acidic surface that resulted in enhanced hydrogen adsorption ability in water solution, which promoted the H;evolution kinetics. In addition, the extended π-conjugated electronic system promoted the separation and migration of photogenerated charge carries in plane of TSC-550 framework, as well as the increasing interlayer C–N interactions in TSC-550 created conductive paths across the layers to tunnel interlayers for rapid electron transportation. As a result, TSC-550 nanosheets showed excellent photocatalytic H;production activity,the AQY achieved 36.4% at 425 nm.

关键词： Degree of polymerization Graphitic carbon nitride Photocatalysis Solar energy Hydrogen

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Experimental Study on Condensation Heat Transfer Characteristics inside an Inclined Wave-Finned Flat Tube of Direct Air-Cooling System

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Journal of Thermal Science 2021年第2期30卷 432-440页

作者： WANG Haitao TAO Tao MEI Xuesong WANG Haijun GU Hongfang State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong UniversityXi'an 710049China Shaanxi Key Laboratory of Intelligent Robots School of Mechanical EngineeringXi'an Jiaotong UniversityXi'an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In this paper,the condensation heat transfer characteristics of parallel flow and counter flow inside an inclined wave-finned flat tube is investigated *** condensation heat transfer coefficients are analyzed based on the experimental *** of experiments show that condensation heat transfer coefficient decreases as the temperature difference Δt=ts-tw increases and mass flow rate *** parallel flow has a similar development with the counter flow,and the condensation heat transfer coefficient of counter flow is less than that of parallel flow under the same air cooling *** addition,condensation heat transfer coefficient correlations are also obtained under experimental *** calculations agree well with the measured data and the agreement is seen to be within ±4% for the parallel flow and ±5% for the counter flow.

关键词： condensation heat transfer wave-finned fiat tube modified model parallel flow counter flow

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Study on boiling heat transfer mechanism based on microlayer evaporation theory 6

Study on boiling heat transfer mechanism based on microlayer...

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6th International Conference on Fluid Mechanics and Industrial Applications, FMIA 2022

作者： Dong, Wu-Han Gao, Ming Shen, Zhong-Xiang Zhang, Li-Xin Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

Based on dynamic microlayer evaporation model. Heat transfer mechanism of nuclear boiling and microlayer thickness under single bubble on heated surface. It has a lot to do with the temperature of the wall. Therefore, this paper studies the mechanism of bubble microlayer and makes comparative analysis with its experiments. It is helpful to master nuclear boiling heat transfer more comprehensively. In the study of individual bubble microlayer thickness. The effects of time and radius on wall temperature are considered in this paper. The theoretical formula of initial thickness of microlayer is deduced. The theoretical formula is compared with the experimental data of microlayer evaporation under the nucleation bubble. It was found that the experimental data fell within ±25% of the formula range. It is consistent with the previous experimental research. © Published under licence by IOP Publishing Ltd.

关键词： Evaporation

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A n-Si/CoOx/Ni:CoOOH photoanode producing 600 mV photovoltage for efficient photoelectrochemical water splitting

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Science China Materials 2022年第12期65卷 3442-3451页

作者： Zhuocheng Yin Yuchuan Shi Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

n-Si,believed as a promising photoanode candidate,has suffered from sluggish oxygen evolution reaction(OER)kinetics and poor chemical stability when exposed to aqueous ***,CoO_(x)/Ni:CoOOH bilayers were successfully deposited on n-Si substrate by atomic layer-deposition(ALD)and photoassisted electrochemical deposition(PED)for stabilizing and catalyzing photoelectrochemical(PEC)water *** comparison to the n-Si/CoO_(x)photoanode as reference,the prepared n-Si/CoO_(x)/Ni:CoOOH photoanode upon the optimized PED process presents a much improved PEC performance for water splitting,with the onset potential cathodically shifted to~1.03 V *** hydrogen electrode(RHE)and the photocurrent density much increased to 20 mA cm^(−2)at 1.23 V *** is revealed that the introduction of Ni dopants increases the work functions of the deposited Ni:CoOOH overlayers,which gives rise to the upward band bending weakened at the n-Si/CoO_(x)/Ni:CoOOH cascading interface while strengthened at the Ni:CoOOH/electrolyte interface(with the band bending shifted from downward to upward),contributing to the decreased and the increased driving forces for charge transfer at the interfaces,***,the balanced driving forces at the interfaces would endow the n-Si/CoO_(x)/Ni:CoOOH photoanode with the best PEC ***,PED has been evidenced superior to ED to dope Ni into CoOOH with the formed overlayer effectively catalyzing and stabilizing PEC water splitting.

关键词： n-Si photoanode work function photoelectrochemical water splitting

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Numerical Study on Influence of Platen Super-Heaters on Heat Deviation in a 600 MW Tangentially Fired Pulverized-Coal Boiler 9th

Numerical Study on Influence of Platen Super-Heaters on Heat...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Chen, Kai Zhang, Yan Deng, Lei Che, Defu School of Mechanic Engineering Xijing University Xi’an710123 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9789811616563

In order to investigate effects of platen super-heaters on the heat deviation in the cross-over pass, numerical simulation of a 600 MW tangentially fired pulverized-coal boiler has been studied. Two cases, building super-heaters or not, were established by FLUENT software in this study. Numerical results agree well with measured data of the utility boiler. Results show platen super-heaters break symmetry of velocity distribution at the furnace outlet. The position where peak temperature occurs is affected by platen super-heaters, while the position where peak velocity occurs is not. Platen super-heaters slightly reduce the temperature deviation at the furnace outlet, and enhances the velocity deviation at the furnace outlet. For this boiler, the velocity deviation is the main reason for the heat deviation in the cross-over pass. The simulation results in this study can provide reference for optimization of temperature deviation and velocity deviation in tangentially fired pulverized-coal boiler. © 2022, Tsinghua University Press.

关键词： Furnaces

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Preferential Formation of Ethylene via Electrocatalytic CO_(2) Reduction on Mesoporous Cu_(2)O Nanoparticles:Synergistic Effects of Pore Structure Confinement and Surface Amine

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Chinese Journal of Chemistry 2024年第16期42卷 1846-1852页

作者： Haifeng Zhang Dun Li Zhifang Chen Yingying Wang Haoyu Sun Feng Liu Maochang Liu Yiqun Zheng Hongwen Huang School of Chemistry Chemical Engineering and MaterialsJining UniversityQufuShandong 273155China College of Materials Science and Engineering Hunan UniversityChangshaHunan 410082China Health Management Department Shandong Vocational College of Light IndustryZiboShandong 255300China International Research Center for Renewable Energy National Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiotong UniversityXi'anShaanxi 710049China

We present a facile synthetic strategy to create mesoporous Cu_(2)O nanocrystals with tunable pore structures and surface functional groups of amine derivatives for efficient and preferable electrochemical conversion of CO_(2) into *** structural characteristics of theseCu_(2)O nanocrystals can be manipulated using a set of amine derivatives,such as pyridine,4,4'-bipyridine,and hexamethylenetetramine,during the oxidative etching process of Cu nanocrystals by bubbling gaseous oxygen in N,N-dimethylformamide *** amine derivatives not only serve as surface functional groups but also significantly affect the resulting pore *** synergistic effect of pore structure confinement and surface amine functionalization leads to the superb Faradaic efficiency(FE)of 51.9% for C_(2)H_(4),respectively,together with the C_(2)H_(4) partial current density of -209.4 mA·cm^(-2) at -0.8 V *** hydrogen electrode(RHE).The relatively high selectivity towards C_(2)H_(4) was investigated using DFT simulations,where 4,4'-bipyridine functionalized Cu_(2)O seemed to favor the C_(2)H_(4) formation with the low free energy of the *** study provides a feasible strategy to manipulate the pore structure and surface functionalization of mesoporous Cu_(2)O nanocrystals by regulating the oxidative etching process,which sheds light on the rational preparation of high-performance CO_(2)RR electrocatalysts.

关键词： Amines Ethylene Cuprous oxide CO_(2)reduction Mesoporous materials

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Homojunction photocatalysts for water splitting

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Nano Research 2022年第12期15卷 10171-10184页

作者： Xiangjiu Guan Shichao Zong Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an710049China Suzhou Academy of Xi’an Jiaotong University Suzhou215123China Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region Ministry of EducationSchool of Water and EnvironmentChang’an UniversityXi’an710064China

Charge-carrier separation is regarded as one of the critical issues of photocatalytic water splitting and could be accelerated by constructing microscopic junctions in *** photocatalysts consisting of different forms of semiconductor with identical compositions could inherit the advantages of heterojunction-based photocatalysts in charge separation due to the built-in electric field,while omitting the potential drawbacks of interfacial lattice distortion by providing continuous band ***,homojunction-based photocatalysts have recently drawn growing attention in water *** this review,the synthetic approaches to preparing photocatalysts with various homojunction structures including p-n junction,phase junction,and facet junction were introduced,together with a comprehensive analysis and discussion on the latest progress in the application of photocatalytic water *** review work is expected to inspire more related work with promoted research on designing efficient homojunction-based photocatalytic systems for water splitting.

关键词： photocatalytic water splitting homojunction charge separation

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Experimental Study on Heat Transfer Characteristics of Supercritical Carbon Dioxide in a Vertical Circular Tube

SSRN

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SSRN 2025年

作者： Yang, Haikuo Nie, Ruishan Zhang, Kui Tian, Wenxi State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

Supercritical carbon dioxide (S-CO2) nuclear energy and power systems have garnered significant attention for flow and heat transfer experiments because of their compact design, advanced circulation methods, and high thermal efficiency, aligning with future trends in nuclear power plant development. However, the dramatic change in physical properties of S-CO2 near its pseudo-critical point can lead to heat transfer deterioration (HTD) in heat exchangers, potentially damaging the S-CO2 Brayton system. This paper presents an experimental study on the HTD of S-CO2 in a vertical circular tube under forced circulation, examining how heat flux, inlet temperature, and system pressure influence *** analysis delves into the mechanisms of HTD, focusing on the buoyancy and flow acceleration effects. Additionally, the study explores the impact of heat flux and system pressure on S-CO2 natural circulation. Ultimately, the research summarizes the flow and heat transfer characteristics of S-CO2 and proposes a new heat transfer correlation formula, demonstrating an error margin within ±25%, which meets practical engineering requirements. This experimental study contributes valuable data to the understanding of flow and heat transfer phenomena in S-CO2, offering significant insights for future applications. © 2025, The Authors. All rights reserved.

关键词： Nuclear energy

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Comparative experimental study on dynamic characteristics of bubble microlayers in small channel flow boiling and pool boiling 6

Comparative experimental study on dynamic characteristics of...

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6th International Conference on Fluid Mechanics and Industrial Applications, FMIA 2022

作者： Shen, Zhongxiang Gao, Ming Dong, Wuhan Zhang, Lixin Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

The microlayer present at the bottom of the bubble plays a very important role in heat transfer during nucleation boiling. In this paper, the dynamic characteristics of microlayer at the bottom of boiling bubble in a small channel were studied by laser interferometry method and high speed camera, and the results were compared with pool boiling experiments. The results show that the bubbles have an obvious tendency to slip in the flow boiling. The microlayer interference fringe is deformed and no longer a complete Newtonian ring. By analyzing the thickness distribution of microlayer in different directions in flow boiling and the change of micro-contact angle in the flow direction, it was found that the micro-contact angle in the flow direction became larger with the growth of bubbles. © Published under licence by IOP Publishing Ltd.

关键词： Contact angle

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Simulation Study on Heat Exchangers Characteristics of Solar Thermal Steam System Based on Aspen Plus 2

Simulation Study on Heat Exchangers Characteristics of Solar...

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2nd International Conference on Algorithms, High Performance Computing and Artificial Intelligence, AHPCAI 2022

作者： Chen, Pengfei Chen, Kang Peng, Huaiwu Zhang, Yanlong Bawaa, Baercheng Zhao, Qiuyang Institute of Solar Engineering Technology Northwest Engineering Corporation Limited Power China Xi'an710065 China Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an China

ISBN: (纸本)9798350334784

In the thermal recovery project of thick oil, there are high standards for steam temperature and flow rate. The solar thermal steam supply system can convert unstable solar energy into stable and efficient carrier heat, which can be used to transfer heat to low-temperature water to produce high-temperature steam and achieve a clean and low-carbon steam supply. The rated pressure of steam and the split ratio of molten salt in the heating system have a great influence on the demand area and heat load of solar panels. In this paper, a simulation is made on the solar thermal steam supply system based on Aspen Plus. The simulation result shows that the increase in pressure will cause a growth in the area of the photothermal concentrator field but will reduce the area used for photovoltaic panels. At the same time, it reduces the heat load of the evaporator and extends its service life. The split ratio affects the molten salt temperature at the outlet of the superheater and the reheater. When the split ratio increases, the heat transfer temperature difference between the two ends of the superheater heat flow decreases, and the heat transfer temperature difference of the reheater grows bigger. Therefore, the molten salt temperature flowing out of the reheater rises. © 2022 IEEE.

关键词： Heat exchangers

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