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Science Bulletin 2022年第5期67卷 520-528,M0004页

作者： Shaohua Shen Jie Chen Yiqing Wang Chung-Li Dong Fanqi Meng Qinghua Zhang Yiliang Huangfu Zhi Lin Yu-Cheng Huang Yanrui Li Mingtao Li Lin Gu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China Department of Physics Tamkang UniversityNew Taipei City 25137TaiwanChina Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen.A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity,but is yet to be ***,we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride(CCN)to triazine-based poly(triazine imide)(PTI),rendering the creation of singleatom cobalt coordinated isotype CCN/PTI ***-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88%at 425 nm for photocatalytic hydrogen production with a rate achieving3538μmol h^(-1)g^(-1)(λ>420 nm),which is 4.8 times that of CCN and 27.6 times that of *** high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration,and the single-atom Co sites for accelerating surface oxidation reaction.

关键词： Photocatalytic hydrogen production Single-atom cobalt Crystalline carbon nitride Poly(triazine imide) Isotype heterojunctions

Visualization Experiments and Piston Effect of Heat Transfer on Supercritical Carbon Dioxide in a Mini Vertical Upward flow

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SSRN 2022年

作者： Lyu, Haicai Wang, Han Bi, Qincheng Niu, Fenglei School of Nuclear Science and Engineering North China Electric Power University Beijing102206 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China

The characteristics of supercritical heat transfer and flow patterns visualization were investigated experimentally. System parameters are pressure of 7.4 ~ 8.44 MPa, the mass flux of 600 ~ 1600 kg·m -2 ·s -1 and heat flux up to 319 kW·m -2 . The basic experimental data of heat transfer coefficient and frictional pressure drop were obtained. Local heat transfer coefficient was calculated with respect to the mass flux, heat flux and pressure. The scenario of in-tube supercritical carbon dioxide was presented by a high-resolution camera. Experimental results show that the heat transfer peak happens when the wall temperature is above the pseudo-critical temperature, and in-tube fluid is lower than the pseudo-critical temperature. Exciting phenomenon of critical opalescence is observed under the pressure of 7.4 MPa and a temperature of 31.68 ˚C. Rapid alternation of sky blue and milky white was captured in an extremely short period time, which may be related to Rayleigh scattering due to drastic density fluctuation. Piston effect of strongly uneven aggregation was formed due to the variation of thermal physical property, which can be used to exposit the mechanism of supercritical heat transfer peak near the pseudo-critical temperature. Ration of density and volumetric coefficient of expansion can be represented for the piston effect to produce the modified Jackson’s correlation, which owns the average error of -0.69% and root-mean-square error of 10.35%. © 2022, The Authors. All rights reserved.

关键词： Visualization

Predicting self-diffusion coefficients of light gases in supercritical carbon dioxide: A molecular dynamics method

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The Journal of Supercritical Fluids 2025年 225卷

作者： Tongjia Zhang Bowei Zhang Jie Zhang Xiaoran Rong Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 PR China

The methanation of CO 2 and supercritical CO 2 (scCO 2 ) fracturing represent effective approaches for CO 2 utilization and greenhouse effect mitigation. In these process, light gases like H 2 , O 2 , CO, CH 4 are commonly involved. However, limited studies have focused on the diffusion behavior of these gases in scCO 2 under high-pressure conditions, as well as a shortage of self-diffusion coefficient data and prediction equations specifically designed for scCO 2 solvents. To address this gap, molecular dynamics (MD) simulations were employed to compute the self-diffusion coefficients of several light gases in scCO 2 across a wide temperature range (313 K–713 K) and at high pressures (75.994 bar, 101.325 bar and 126.656 bar) under infinitely dilute conditions. The effects of temperature, density, viscosity, molecular mass, and solute–solvent interaction energy on the self-diffusion behavior were systematically analyzed. Two empirical equations (a Speedy–Angell-type power-law equation and a newly developed equation incorporating temperature, density, and viscosity) were refitted based on simulation data. The overall relative errors are 4.52 % and 4.44 %, respectively, indicating an improved accuracy compared to conventional experimental and MD-based empirical equations.

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Numerical investigation of natural convection characteristics of a heat pipe-cooled passive residual heat removal system for molten salt reactors

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Nuclear Science and Techniques 2020年第7期31卷 25-33页

作者： Cheng-Long Wang Hao Qin Da-Lin Zhang Wen-Xi Tian Guang-Hui Su Sui-Zheng Qiu Department of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The limited availability of studies on the natural convection heat transfer characteristics of fluoride salt has hindered progress in the design of passive residual heat removal systems(PRHRS)for molten salt *** paper presents results from a numerical investigation of natural convection heat transfer characteristics of fluoride salt and heat pipes in the drain tank of a *** results are compared with experimental data,demonstrating the accuracy of the calculation *** distribution of fluoride salt and heat transfer characteristics are obtained and *** radial temperature of liquid fluoride salt in the drain tank shows a uniform distribution,while temperatures increase with increase in axial height from the bottom to the top of the drain *** addition,natural convection intensity increases with increase in height of the heat pipes in the *** between heat pipes has no obvious effect on the natural convection heat transfer *** study will contribute to the design of passive heat removal systems for advanced nuclear reactors.

关键词： passive characteristics pipes

Steady-State Multi-Physics Coupling Analysis of Heat Pipe Cooled Reactor Core

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SSRN 2022年

作者： Zhang, Zhipeng Wang, Chenglong Guo, Kailun Tian, Wenxi Qiu, Suizheng Su, Guanghui Department of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

Due to the advantages of mobility, safety and universality, the heat pipe reactors have great competitiveness in many applications such as strategic defense locations, remote communities, and emergency locations. In addition, most of the heat pipe reactors are designed as solid-state reactors, which avoid the two-phase flow problem caused by the coolant transformation and make it possible to analyze the reactor with multiple physical field coupling. In this work, a typical heat pipe reactor has been carried out a 3-D neutronic-thermal-mechanical analysis, and steady state analysis is performed by OpenMC coupled with COMSOL. Coupling calculation results show that under normal operation, the maximum temperature and thermal expansion of core is 1338.94 K and 2.53 mm. In the steady-state coupling process, the influence of temperature parameters on physical calculation is mainly reflected in k eff and its power level, the maximum temperature drops from 1347.26 K to 1338.94 K, but it has little influence on power distribution. By coupling calculations, the maximum stress of the reactor is reduced by 5.78 MPa. The research results will support the subsequent development of multi-physics coupled transient analysis code for heat pipe reactors. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

Experimental study on mercury content in flue gas of coal-fired units based on laser-induced breakdown spectroscopy

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Plasma Science and Technology 2020年第7期22卷 75-82页

作者： Kai RONG Zhenzhen WANG Ruomu HU Renwei LIU Yoshihiro DEGUCH Junjie YAN Jiping LIU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China Graduate School of Technology Industrial and Social SciencesTokushima UniversityTokushima 770-8501Japan Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China

Accurate measurement of trace heavy metal mercury(Hg) in flue gas of coal-fired units is great significance for ecological and environmental *** gas was used to simulate the actual flue gas of a power plant in this study.A laser-induced breakdown spectroscopy(LIBS)system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure,Hg concentration in mixed gas and delay time on Hg *** experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise *** Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed *** Hg signal intensity and signal to noise ratio decreased with the increase in delay *** to the above results,the optimized measurement conditions can be *** Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method *** relative error of prediction of the test sample obtained by the internal standard method was within 11.11%.The relative error of prediction of the traditional calibration method was less than 14.54%.This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS.

关键词： laser-induced breakdown spectroscopy flue gas trace heavy metal quantitative analysis

Design and Optimal Thermal Efficiency Contrastive Analysis on Closed Brayton Cycle Systems with Different Fluids of Fluoride-Salt-Cooled High-Temperature Advanced Reactor

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Yun, Shichang Zhou, Xingguang Jiang, Dianqiang Lv, Xindi Feng, Zhenyu Wu, Wenqiang Tian, Wenxi Qiu, Suizheng Su, Guanghui Zhao, Quanbin Liu, Xiuting State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China

To match the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactor, the closed Brayton cycle system was selected as the energy conversion system, and the thermodynamic analysis, conjugate gradient optimization, and exergy analysis were performed. The pinch point constraint method based on simultaneous equations was proposed to improve the calculation efficiency and ensure the unity of comparison standards, and the exergy analysis was used to quantify and optimize the exergy losses for the equipment. For the simple regenerative cycle configuration, the thermal efficiency and mass flow rate of the cycle system with various fluids (far-critical fluids: air, nitrogen, helium, and argon, near-critical fluids: carbon dioxide, sulfur hexafluoride, propane, and xenon) were analyzed. The results of the thermodynamic analysis show that the thermal efficiency of the sulfur hexafluoride cycle is the highest and reaching 46.6% with the simple regenerative cycle configuration. The thermal efficiency of the far-critical fluid cycle is more sensitive to turbine efficiency. The results of the exergy analysis show the CO2 cycle has the highest potential to improve thermal efficiency, which has the highest improvement from 43.48% to 49.31% with the recompression process. The method and conclusion of this paper can provide references for the design and optimization of the Brayton power cycle system © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

Design and Optimal Thermal Efficiency Analysis on Closed Brayton Cycle System of Fluoride-Salt-Cooled High-Temperature Advanced Reactor (Fustar)

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Yun, Shichang Zhou, Xingguang Jiang, Dianqiang Lv, Xindi Feng, Zhenyu Wu, Wenqiang Tian, Wenxi Qiu, Suizheng Su, G.H. Zhao, Quanbin Liu, Xiuting State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China

To match the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR): the high temperature, inherent safety, compact structure, and modularization, the closed Brayton cycle system was selected as the energy conversion system, and the enthalpy analysis, conjugate gradient optimization, and exergy analysis were performed. The pinch point constraint method based on simultaneous equations was proposed to improve the calculation efficiency and ensure the unity of comparison standards, and the exergy analysis was used to quantify and optimize the exergy losses for the equipment. For the simple regenerative cycle configuration, the thermal efficiency and mass flow rate of the cycle system with various fluids (far-critical fluids: air, nitrogen, helium, and argon, near-critical fluids: carbon dioxide, sulfur hexafluoride, propane, and xenon) were analyzed, at the highest thermal efficiencies. The results of enthalpy analysis show that the thermal efficiency of the sulfur hexafluoride cycle is the highest with the simple regenerative cycle configuration. The thermal efficiency of the far-critical fluid cycle is more sensitive to turbine efficiency. The exergy analysis shows the CO2 cycle has the highest potential to improve thermal efficiency. The method and conclusion of this paper can provide references for the design and optimization of the Brayton power cycle system. © 2022, The Authors. All rights reserved.

关键词： Enthalpy

Thermal Modulation of Radiation Fields Enhancing the Adaptability of Cpv-Hydrogen Systems to Hot Outdoor Conditions

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SSRN 2023年

作者： Zhu, Yizhou Zhang, Ting’an Geng, Jiafeng Jing, Dengwei Xi'an University of Science and Technology China Department of Chemical Engineering School of Water and Environment Chang'an University Shaanxi Xi’an710064 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The efficiency of photovoltaic (PV) modules operating outdoors often subject to significant decrease due to high PV surface temperature under hot outdoor conditions despite of the high irradiation in this period. Meanwhile, the commercial electrolytic water splitting unit requires additional heat sources to preheat the electrolyte, which is neither economical nor energy efficient. This study introduces a proton exchange membrane (PEM) water electrolyzer system coupled with concentrated photovoltaic (CPV) and a pipe-based liquid spectral beam splitting filter acting also as an electrolyte preheater. The results of continuous experiments during local summer daytime show that the average PV surface temperature of the proposed system can be reduced by 23.5 K compared to that without spectral beam splitting filter. Moreover, the average efficiencies of photovoltaic, electrolysis and solar-to-hydrogen can be increased by 7.5%, 8.1% and 5.2%, respectively. Both simulation and experimental results confirm that our design can reduce the sensitivity of system efficiency toward weather factors, especially high-intensity summer irradiation. This work provides a promising option for application of large-scale solar hydrogen production in regions with sufficient sunlight while high outdoor temperature. © 2023, The Authors. All rights reserved.

关键词： Hydrogen production

Study on Sewage Sludge Drying System with Built-in Solar Drying Bed 3

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Study on Sewage Sludge Drying System with Built-in Solar Dry...

3rd International Symposium on Architecture Research Frontiers and Ecological Environment, ARFEE 2020

作者： Gu, Zhipan Yang, Jichun Liu, Jing Tao, Leren Zhang, Ye Huang, Lihao Instiute of Refrigeration and Cryogenics School of Energy and Power University of Shanghai for Science and Technology Shanghai200093 China School of Architecture and Civil Engineering Jiaxing University Jiaxing Zhejiang314001 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

In this paper, the renewable energy solar energy is used as the heat source. The combination of solar drying bed and traditional hot air drying can effectively reduce energy consumption and operation cost. The drying chamber is divided into three layers. The top air supply outlet supplies hot air, the middle layer places wet sludge, and the bottom layer uses hot water coil to dry the sludge. The whole drying process is a heat and mass transfer process with convective heat transfer and radiation heat transfer. After analysis and comparison with traditional energy drying, it is found that drying 97.5kg of sewage sludge will save 79% energy, save 12.84 kg of standard coal, reduce 32 kg of carbon dioxide and 1.284 kg of sulphur dioxide. © The Authors, published by EDP Sciences, 2021.

关键词： Drying