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Chemical Research in Chinese Universities 2022年第5期38卷 1243-1250页

作者： LIN Zhi ZHANG Zhengqi WANG Yiqing PENG Zhiming WANG Xinxin WANG Ruizhe HUANG Yu-Cheng MENG Fanqi LI Mingtao DONG Chung-Li ZHANG Qinghua GU Lin SHEN Shaohua International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049P.R.China Department of Physics Tamkang UniversityNew Taipei City 25137TaiwanP.R.China Institute of Physics Chinese Academy of SciencesBeijing 100190P.R.China

Polymeric carbon nitride(PCN)has emerged as a promising candidate for photocatalytic hydrogen evolution,but its dependence on scarce and high-cost noble metal co-catalysts severely limits its extensive *** will be of great promise to develop non-noble metal single-atom co-catalysts with low-cost and high atom utilization to improve the photocatalytic performance over ***,single Ni atoms are successfully anchored onto carbon-vacant PCN nanosheets(CCN-SANi)via a two-step ammonia thermal treatment and photo-deposition *** calculations and experimental results demonstrate that the optical absorption property and the charge transfer ability of CCN-SANi have been significantly improved with the introduction of single Ni atoms to form Ni-N3 *** comparison to carbon-vacant PCN(CCN)loaded with Ni clusters,the obtained CCN-SANi exhibits 11.4 times increased photocatalytic performance,with the highest hydrogen evolution rate reaching 511μmol/(g·h),which is even 1.7 times higher than that of CCN loaded with Pt *** research proposes an inspiring and reliable strategy to design novel single-atom semiconducting polymers with electronic structures manipulated for efficient photocatalysis.

关键词： Photocatalytic hydgogen evolution Single metal atom Polymeric carbon nitride

Atomic Insights into Hydrogen Peroxide Decomposition on the Surface of Pure and Pre-Treated Silver: A Reactive Molecular Dynamics Simulation Study

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SSRN 2023年

作者： Zhao, Xiao Feng, Yiming Zhang, Bowei Jin, Hui Wei, Xianggeng State Key Laboratory of Solid Propulsion Northwestern Polytechnical University Shaanxi Xi’an710072 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Based on ReaxFF molecular dynamics simulation, H2O2 decomposition on pure and pre-treated silver catalyst is studied at a microscopic level. The pretreatment undergoes a surface annealing with redundant H2O2 on top of catalyst. The simulation results indicate that H2O2 decomposition can be drastically accelerated by elevating temperature. The extent of decomposition is closely related to bond, hydrogen bond, and potential energy of simulation system. It is found that H2O2 decomposition follows a four-stage HO-OH bond break mechanism while it needs three times longer for pre-treated silver catalyst than pure silver catalyst. The activation energy of pre-treated silver catalyst is about 50% lower than pure silver catalyst. However, the overall reaction rate of pre-treated silver catalyst is about an order of magnitude slower than pure silver catalyst, which owes to the much smaller pre-factor. It is believed that although the pretreatment causes silver oxide to be formed on the surface, it leads to more hydrogen and oxygen atoms deposited so that most active sites for catalytic reaction are blocked for further decomposition. This may be helpful to understand the inherent mechanism of H2O2 decomposition on silver-based catalyst and provide instructional advice for further catalyst modification design. © 2023, The Authors. All rights reserved.

关键词： Catalysts

Influence of Bentonite on Copper Corrosion in Simulated Repository Electrolyte

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SSRN 2024年

作者： Ning, Zhiyuan Zhou, Qulan Li, Na Macdonald, Digby D. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Departments of Nuclear Engineering and Materials Science and Engineering University of California at Berkeley BerkeleyCA94720 United States

The impact of bentonite on the corrosion of oxygen-free copper (OF-Cu) and oxygen-free phosphorous copper (OFP-Cu) in prototypical groundwater environments (standard reference electrolyte, SRE) simulating the storage of copper High-Level Nuclear Waste (HLNW) cannisters in granitic rock repositories is explored. At low corrosion potentials (-0.1V), bentonite suppresses copper corrosion in SRE through the anion-exclusion effect, with its inhibitory impact intensifying at higher bentonite concentrations. As the corrosion potential rises, particularly beyond the "bell-shaped" region in the polarization curve, bentonite's enhanced adsorption of metal cations increases the corrosion current. Additionally, bentonite hydrolysis producing silicate ions that accelerates pitting corrosion, culminating in passive film breakdown. This dual mechanism may amplify intergranular corrosion. In environments where bentonite exacerbates corrosion, OFP-Cu demonstrates superior corrosion resistance, though the introduction of phosphorus may influence the acceleration of intergranular corrosion following passivity breakdown. © 2024, The Authors. All rights reserved.

关键词： Copper corrosion

A Three-Dimensional Curve Interface Reconstruction Algorithm for Two-Phase Fluid flow

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SSRN 2024年

作者： Chen, Yujie Gong, Junhua Sun, Dongliang Han, Dongxu Wang, Peng Yu, Bo Tao, Wen-Quan School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Key Laboratory of Thermo–Fluid Science and Engineering Ministry of Education School of Energy & Power Engineering Xi’an Jiaotong University Shaanxi 710049 China

The curve interface reconstruction algorithm has received significant attention in the context of two-dimensional two-phase flow. However, it remains absent in the three-dimensional scenario. This paper proposes a novel three-dimensional curve interface reconstruction (CIR) algorithm to address this challenge within structured meshes for the first time. Specifically, a portion of the spherical surface is employed to reconstruct the three-dimensional curve interface segment, with the radius and center coordinates determined by curvature and mass conservation constraints, respectively. To enhance curvature accuracy, a sphere-based iterative reconstruction (SIR) algorithm is proposed to calculate the reconstructed distance function (RDF) for the three-dimensional curve interface. Various tests involving the reconstruction and interface capture of spherical, ellipsoidal, and cubic objects demonstrate that the coupled SIR and CIR (SIR-CIR, simplified by SCIR) method achieves high accuracy, particularly with coarse mesh resolutions. Additionally, the SCIR method offers the advantages of straightforward implementation and coding for interface reconstruction in two-phase flow research. This advantage results in reduced computational costs compared to the coupled volume-of-fluid and level set (VOSET) method, which also utilizes an iterative method to solve RDF. © 2024, The Authors. All rights reserved.

关键词： Spheres

Thermal Characteristics and Structural Parameters Optimization of Apg/Cu/Pcm Integrated Architecture

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SSRN 2024年

作者： Su, Lizheng Zhang, Tianning Li, Xiaoyang Li, Dong Jiang, Xinyu Xie, Zhongnan Xi'an Electronic Engineering Research Institute Xi’an710100 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co. Ltd. Beijing100088 China

The challenges faced by radar seeker primarily stem from inadequate heat dissipation in chips and excessive weight. To address these issues, this study introduces a novel integrated phase-change heat sink architecture, composed of a copper alloy matrix, annealed pyrolytic graphite (APG), and phase-change materials (PCMs) serving as heat conduction reinforcements. The numerical analysis of the heat dissipation performance of this architecture is conducted using Fluent software. The study evaluates the impact of APG anisotropy, APG/Cu interface thermal resistance, APG thickness, and surface area on the heat conduction efficiency. Results demonstrate that APG facilitates a uniform in-plane temperature distribution, allowing PCMs to absorb heat more evenly. Consequently, APG proves effective in enhancing heat dissipation and safeguarding chips from high temperatures. In comparison to a pure copper component, the APG/Cu/PCM structure reduces chip temperature by a substantial 56.27%. Furthermore, increasing the surface area of APG generally contributes to an enhanced heat transfer capability of entire architecture. The paper presents a quantitative relationship between APG surface area and optimal thickness. Importantly, APG satisfies the lightweight requirement, further emphasizing its suitability for addressing the thermal challenges in radar seeker structures. © 2024, The Authors. All rights reserved.

关键词： Phase change materials

Supercritical Co2 -Promoted Degradation of Polystyrene to Aromatic Oils with Nio@C Catalyst

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SSRN 2024年

作者： Liu, Yanbing Shi, Jinwen Zhuang, Zitong Kang, Xing Mao, Liuhao Li, Yi Jin, Hui Zhao, Qiuyang Guo, Liejin International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 28 West Xianning Road Shaanxi Xi’an710049 China

Exploring new system for chemical recycling of plastic is an effective way to convert plastic waste into energy. Herein, the use of supercritical CO2 (Sc-CO2) to promote the catalytic degradation of polystyrene (PS) with high yield of aromatic oils was proposed. Sc-CO2 provided a homogeneous environment for the reaction, which not only facilitated the swelling of PS, but also inhibited the formation of coke, beneficial for the degradation of PS to aromatic oils. Importantly, CO2 was be consumed as an oxidant to generate new product and reduce greenhouse gas emission. The doped carbon material in NiO, which was stable in Sc-CO2 and had a simple preparation process, enriched the porous structure and increased the acidic sites, thus improving the catalytic activity. Under the co-action of Sc-CO2 and NiO@C, the yield of aromatic oils produced from PS was up to 89.3 ± 0.6 wt% at 300oC with a reaction time of 2 h and a catalyst loading amount of 10 wt%. Moreover, the NiO@C catalyst were used for three cycles without obvious change in the catalytic performance. The efficient catalytic degradation of PS to aromatic oils by Sc-CO2 promoted NiO@C catalysis provides a potential route for simultaneously recycling plastic and sequestering carbon. © 2024, The Authors. All rights reserved.

关键词： Carbon dioxide

Chemical Kinetics Simulation on Nitrogen Migration Characteristics During Co-Combustion of Ammonia and Coal Under Deeply Fuel-Air Multistage Conditions

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SSRN 2024年

作者： Dai, Liangxu Wang, Chang'an Hou, Yujie Ma, Guowei Chen, Yongxu Hurera, Abu Zhou, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China China Energy Science and Technology Research Institute Co. Ltd. Nanjing210046 China

mmonia, a carbon-free fuel, is attracting an ever-increasing attention. Coal/ammonia co-combustion in coal-fired power plants is considered an effective and fast approach to achieving the global decarbonization goal. However, one bottleneck of the utilization of ammonia fuel is the possible increased NOx emissions. The supply strategy of ammonia can affect the reduction of NOx by NH3. Few studies have explored the influence of ratios of ammonia as a secondary fuel and the secondary air volume on NOx emissions, which could be effective methods to reduce pollution. In this work, a chemical kinetics model was established to study the NOx behaviors during coal/NH3 co-firing in deeply fuel-air multistage conditions. The effects of the ammonia distribution strategies such as the ratio of NH3 as a secondary fuel, the injection position of secondary fuel, and corresponding air distribution with different NH3 co-firing ratios (CR-NH3) on the ammonia reactivity for NOx-reduction were studied. The results show that ammonia should be used as a primary fuel entering the main combustion zone under small CR-NH3 conditions to mitigate the NOx emissions;otherwise, ammonia is inclined to be used as a secondary fuel entering the reduction zone under large CR-NH3 conditions. NOx generation is also found to primarily occur in the burnout zone in fuel-air multistage combustion. Thus, the burnout zone should be given priority to decrease the NOx emissions. With the delay of secondary fuel injection in the reduction zone, the escaping ammonia keeps increasing in the outlet of the reduction zone. Then it is completely burned in the burnout zone, which leads to an increase in NOx emissions. The volume flow rate of NOx shows a downward trend on the whole with the ratio of secondary air increased. The air distribution can alter the function of the reduction zone in both generating and eliminating NO. The findings can provide some guidance to effectively decrease NOx emissions in coal/NH3 co-fi

关键词： Coal

Transient Thermoelectric Characteristics of the Principle Prototype for the Heat Pipe Cooled Nuclear Silent Themoelectirc Reactor (Nuster)

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SSRN 2023年

作者： Guo, Kailun Zhang, Yin Lin, Xingyang Huang, Jinlu Wang, Chenglong Qiu, Suizheng Tian, Wenxi Su, Guanghui School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy And Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

This paper proposes an optimized design for the Heat Pipe ThermoElectric Generator(HPTEG) principle prototype. The refined scheme adopts high-temperature sodium heat pipes as heat transfer elements to enhance the overall operating temperature of the device. It adopts Half-Hessler(HH) alloy ThermoElectric Generator(TEG) arranged on the upper and lower sides of the heat exchanger to enhance the thermoelectric conversion efficiency of the device. A heat pipe dynamic conduction model is established to simulate the start-up process of the sodium heat pipe. A TEG model is developed, which is able to simulate the three-dimensional thermoelectric properties of the TEG. The numerical simulation platform is used to analyze the steady-state and transient thermoelectric properties of the refined HPTEG prototype. This study provides data support for the subsequent design modification of the future HPTEG principle prototype and provides ideas for the 3D transient calculations of the solid-state heat pipe reactors. © 2023, The Authors. All rights reserved.

关键词： Heat pipes

Study on the Safety Characteristics of Fluoride-Salt-Cooled High-Temperature Advanced Reactor

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SSRN 2023年

作者： Lv, Xindi Zhang, Dalin Li, Xinyu Zhou, Xingguang Jiang, Dianqiang Su, Guanghui Tian, Wenxi Qiu, Suizheng 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

FuSTAR is a small, modular fluoride-salt-cooled high-temperature advanced reactor, proposed by Xi'an Jiaotong University (XJTU), aiming at fulfilling the requirements of Gen IV nuclear system and meanwhile ensuring the inherent safety and economics. In order to evaluate the safety performance of FuSTAR, five typical design basis accidents are selected for safety analysis with different initial events. The sensitivity analysis is also performed. The results of transient accidents indicate that safety of FuSTAR has been guaranteed in URIA and ULOF. Meanwhile, the maximum limit of external parameters causing ULOHS and UOC are obtained by sensitivity analysis. In the ULOF and ULOHS, the peak of fuel temperature, cladding surface temperature and core outlet temperature of coolant are below their safety limits. Therefore, FuSTAR exhibits acceptable safety under design basis accidents. This study will provide supports in verifying the rationality of the design and the subsequent optimization of FuSTAR. © 2023, The Authors. All rights reserved.

关键词： Sensitivity analysis

Experimental Study on flow and Heat Transfer of Medium-Prandtl-Number Fluid Along a Hexagonal Helical Cruciform Seven-Rods

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SSRN 2023年

作者： Jiang, Dianqiang Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Guanghui 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

A novel type of nuclear fuel named helical cruciform fuel may realize self-supporting for adjacent elements and improve heat transfer, both of which contribute to increasing the power density of the reactor. The flow and heat transfer characteristics of a hexagonal helical cruciform seven-rod bundle were experimentally investigated in the present work. 200 sets of isothermal frictional resistance experiments and 199 sets of heat transfer experiments were finished. The laminar flow region (200 © 2023, The Authors. All rights reserved.

关键词： Reynolds number