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Performance enhancement for nanofluid-cooled microchannel heat sink

Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and engineering 2012年第SUPPL.期20卷 169-180页

作者： Lin, Lin Wang, Xiaodong Wang, Zhenhua Department of Thermal Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China Xi'an Shaangu Power Co. LTD Xi'an 710075 China

Based on selecting the proper formulas of thermal conductivity and viscosity for nanofluids, a three-dimensional fluid-solid conjugated model was developed to analyze the effect of the heat sink structure, the nanoparticle kind, diameter and volume fraction, and the base fluid kind on the cooling performance of microchannel heat sink. The results showed that: (1) thermal dispersion effect caused by nanoparticle random motion enhanced the thermal convection of nanofluid thus enhances significantly the cooling performance of heat sink;(2) the enhancement of nanofluids was closely dependent on the heat sink structure and the dependence was distinct from the pure fluid, hence the heat sink structure was needed to be optimized for nanofluids as coolants;(3) as the nanoparticle volume fraction increases, the thermal resistance reduced and the pressure increased, the water-based Al2O3 nanofluid with 0.5% volume fraction was the optimal coolant which caused 10.1% decrease in the thermal resistance and only 0.38% increased in the pressure drop;(4) although the nanoparticle size had a small effect on the thermal resistance, nanoparticles with small diameter were recommended with consideration of stability of nanofluids;(5) Al2O3 nanoparticle was superior to TiO2 and CuO, and water was the better base fluid than ethylene glycol and engine oil.

关键词： Nanoparticles

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Expression of oxidation ability for metallurgical slags based on the ion and molecule coexistence theory

Beijing Keji Daxue Xuebao/Journal of University of Science a...

引用

Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing 2013年第12期35卷 1569-1579页

作者： Li, Peng-Cheng Li, Jin-Yan Zhang, Meng Zhang, Jian-Liang Zhang, Jian Yang, Xue-Min State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Beijing Metallurgical Equipment Research and Design Institute Company Limited China Metallurgical Group Corporation Beijing 100029 China

The defined oxidation ability of metallurgical slag based on the ion and molecule coexistence theory (IMCT), i.e., the comprehensive mass action concentration of iron oxides NFetO, was verified by comparing the calculated NFetO and the reported activity of iron oxides aFetO in selected 14 slag systems. To calculate NFetO in the selected slag systems, a thermodynamic model for calculating the mass action concentrations of structural units in CaO-SiO2-MgO-FeO-Fe2O3-MnO- Al2O3-P2O5 type slag systems, i.e., the IMCT-Nt thermodynamic model was developed. NFetO in the other 13 slag systems can be obtained by simplifing this IMCT-Nt. It is shown that the defined comprehensive mass action concentration of iron oxides NFetO is more accurate than the measured activity of iron oxides aFetO in characterizing the oxidation ability of the selected FetO-containing slag systems.

关键词： Manganese oxide

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Tensorial properties via the neuroevolution potential framework: Fast simulation of infrared and Raman spectra

arXiv

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arXiv 2023年

作者： Xu, Nan Rosander, Petter Schäfer, Christian Lindgren, Eric Österbacka, Nicklas Fang, Mandi Chen, Wei He, Yi Fan, Zheyong Erhart, Paul Institute of Zhejiang University-Quzhou Quzhou324000 China College of Chemical and Biological Engineering Zhejiang University Hangzhou310058 China Department of Physics Chalmers University of Technology GothenburgSE-41296 Sweden State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing China Department of Chemical Engineering University of Washington SeattleWA98195 United States College of Physical Science and Technology Bohai University Jinzhou121013 China

Infrared and Raman spectroscopy are widely used for the characterization of gases, liquids, and solids, as the spectra contain a wealth of information concerning in particular the dynamics of these systems. Atomic scale simulations can be used to predict such spectra but are often severely limited due to high computational cost or the need for strong approximations that limit application range and reliability. Here, we introduce a machine learning (ML) accelerated approach that addresses these shortcomings and provides a significant performance boost in terms of data and computational efficiency compared to earlier ML schemes. To this end, we generalize the neuroevolution potential approach to enable the prediction of rank one and two tensors to obtain the tensorial neuroevolution potential (TNEP) scheme. We apply the resulting framework to construct models for the dipole moment, polarizability, and susceptibility of molecules, liquids, and solids, and show that our approach compares favorably with several ML models from the literature with respect to accuracy and computational efficiency. Finally, we demonstrate the application of the TNEP approach to the prediction of infrared and Raman spectra of liquid water, a molecule (PTAF–), and a prototypical perovskite with strong anharmonicity (BaZrO3). The TNEP approach is implemented in the free and open source software package gpumd, which makes this methodology readily available to the scientific community. Copyright © 2023, The Authors. All rights reserved.

关键词： Computational efficiency

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Aeroelastic Analysis of Preset Angle for A Typical Airfoil Section with Cubic Nonlinear Stiffness

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Journal of Physics: Conference Series 2019年第1期1300卷

作者： Guofang Nan Di Ding Weitao Wang School of Energy and Power Engineering University of Shanghai for Science and Technology China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering 516 Jungong Road 200093 Shanghai P.R. China

The influences of the preset angle on the dynamic responses of the typical airfoil section with cubic nonlinear stiffness were investigated under consideration of the aerodynamic flutter onset due to certain angle of attack. The typical airfoil model with cubic nonlinear stiffness is developed to analyze the plunging and the pitching motions for the airfoil section. Based on the Grossman's quasi steady aerodynamic model, the aerodynamic lift and the moment can be obtained and then the equation of motion for the airfoil section is derived by applying the Lagrange theorem. The effects of the preset angle and the oncoming flow speed on the nonlinear dynamics are analyzed by means of the bifurcation diagram, the frequency-amplitude diagram, the time history, etc. Simulation results show that the preset angle influences the intensity of the vibration, moderate or severe, stable or unstable, even under certain circumstance, the jump and chaos phenomenon occur; and the oncoming flow speed affects the distribution of the vibration energy for the plunging and the pitching motions. The unstable stall region for the responding parameters should be avoided to keep the airfoil safe in engineering practice. Some qualitative and quantitative rules are obtained for the airfoil design and the flutter suppression.

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Exploring Geometric Chirality in Nanocrystals for Boosting Solar-to-Hydrogen Conversion

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Angewandte Chemie 2024年第45期136卷

作者： Wenlong Fu Qi Gao Chunyang Zhang Lili Tan Biao Jiang Chengyu Xiao Prof. Maochang Liu Prof. Peng-peng Wang State Key Laboratory for Mechanical Behavior of Materials Shaanxi International Research Center for Soft Matter School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 PR China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 PR China

Advancing catalyst design is pivotal for the enhancement of photocatalytic processes in renewable energy conversion. The incorporation of structural chirality into conventional inorganic solar hydrogen nanocatalysts promises a significant transformation in catalysis, a feature absent in this field. Here we unveil the unexplored potential of geometric chirality by creating a chiral composite that integrates geometric chiral Au nanoparticles (NPs) with two-dimensional C 3 N 4 nanosheets, significantly boosting photocatalytic H 2 evolution beyond the achiral counterparts. The superior performance is driven by the geometric chirality of Au NPs, which facilitates efficient charge carrier separation through the favorable C 3 N 4 -chiral Au NP interface and chiral induced spin polarization, and exploits high-activity facets within the concave surfaces of chiral Au NPs. The resulting synergistic effect leads to a remarkable increase in photocatalytic H 2 evolution, with an apparent quantum yield of 44.64 % at 400 nm. Furthermore, we explore the selective polarized photo-induced carrier separation behavior, revealing a distinct chiral-dependent photocatalytic HER performance. Our work advances the design and utilization of chiral inorganic nanostructures for superior performance in energy conversion processes.

关键词： Geometric chirality Nanoparticles Photocatalytic hydrogen evolution reaction Chiral effect

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A [email protected] reinforced concrete structure derived from nickel foam for efficient visible-light H 2 production

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Chemical engineering Journal 2020年 393卷

作者： Chao Zhang Baoquan Liu Xi Cheng ZhenMei Guo Tao Zhuang Zhiguo Lv State Key Laboratory Base for Eco-chemical Engineering Key Laboratory of Multiphase Flow Reaction and Separation Engineering of Shandong Province College of Chemical Engineering Qingdao University of Science and Technology Qingdao 266042 China Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology Guangxi University Nanning 530004 China Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) College of Chemistry Nankai University Tianjin 300071 China

High-efficient noble-metal-free photocatalyst is vital to realize high H 2 evolution. In consideration of this, we design a [email protected] reinforced concrete structure derived from nickel foam (NF) via a simple one-pot oil bath strategy. The whole preparation process is started with the growth of NiS rods on NF. Subsequently, NiS rods are encased in CdS gradually under oil both conditions. After the combination of NiS rods and CdS, the photoelectrical properties of primeval CdS are greatly optimized, e.g. , photoelectric responsiveness, impedance and light absorption capacity. Moreover, the H 2 evolution rate of [email protected] is increased significantly from 2706 to 40601 μmol g −1 h −1 under visible-light irradiation (λ > 420 nm), which is about 15 times higher than that of pure CdS, thereby confirming the excellent synergistic effect between NiS rods and CdS. Additionally, the photocatalytic performance of [email protected] was stronger than that of CdS/NiS-NPs (6726 μmol g −1 h −1 ) and CdS-NPs/NiS (1639 μmol g −1 h −1 ), highlighting the advantages of CdS (prepared using oil bath treatment) and NiS rods (originated from NF growth). Lastly, according to experiment data and DFT calculation results, a viable mechanism for [email protected] is tentatively proposed.

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Functional Polyion Complex Vesicles Enabled by Supramolecular Reversible Coordination Polyelectrolytes

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Angewandte Chemie 2019年第25期131卷

作者： Wenjuan Zhou Jiahua Wang Peng Ding Xuhong Guo Martien A. Cohen Stuart Junyou Wang State Key Laboratory of Chemical Engineering and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 P. R. China

Reported here is a new class of PICsomes (vesicles formed by polyelectrolyte complexation) in which the anionic/neutral diblock copolymer is replaced by an anionic, reversible, supramolecular polyelectrolyte based on metal–ligand coordination. This supramolecular polyelectrolyte forms exclusively inside the wall of the assembly, and therefore self‐adjusts its length to that of the cationic block provided. Moreover, the supramolecular coordination polyelectrolytes introduce new and tunable properties and functions associated with the specific metal. As a proof‐of‐concept Mn‐based PICsomes were prepared and display high magnetic relaxivity, as well as enhanced contrast in in vitro magnetic resonance imaging tests. The simplicity of our approach, together with the new functions derived from the metal ions, demonstrates a robust strategy for the preparation of a variety of PICsomes with well‐defined and tunable structures and properties.

关键词： Elektrolyte Mizellen Polymere Selbstorganisation Vesikel

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Anthracite combustion catalyzed by Ca-Fe-Ce series catalyst

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Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology 2009年第4期37卷 421-426页

作者： Gong, Xu-Zhong Guo, Zhan-Cheng Wang, Zhi State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Acad. of Sci. Beijing 100190 China Graduate University of Chinese Acad. of Sci. Beijing 100049 China Key Laboratory of Recycling and Ecological Metallurgy University of Science and Technology Beijing Beijing 100083 China

The effect of Ca-Fe-Ce series catalyst on the characteristics of anthracite combustion was investigated by thermo-gravimetric analysis. The results showed that there may be a synergetic effect among the components in the composite catalyst and the composite catalyst exhibits better performance than the single one for the anthracite combustion. The combustion characteristics of anthracite are affected by the dispersion of catalyst, heating rate and combustion atmosphere. The catalytic effect is enhanced by increasing the catalyst dispersion. The reduction degree of ignition temperature increases with the increase of heating rate. The ignition temperature decreases significantly with the increase of O2 concentration.

关键词： Thermogravimetric analysis

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Heterostructures by Templated Synthesis of Layered Double Hydroxide to Modulate the Electronic Structure of Nickel Sites for a Highly Efficient Oxygen Evolution Reaction

SSRN

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SSRN 2023年

作者： Xu, Kexin Zhong, Haihong Song, Jie Estudillo-Wong, Luis Alberto Yang, Jun Feng, Yongjun Zhao, Xiaojuan Alonso-Vante, Nicolas State Key Laboratory of Chemical Resource Engineering Beijing Engineering Center for Hierarchical Catalysts College of Chemistry Beijing University of Chemical Technology No. 15 Beisanhuan East Road Beijing100029 China School of Chemistry and Chemical Engineering Hainan University No. 58 Renmin Road Haikou570228 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China Institute of High Energy Physics Chinese Academy of Science Beijing100190 China Departamento de Biocienciase Ingeniería CIIEMAD-IPN Instituto Politécnico Nacional Ciudad de México07340 Mexico IC2MP UMR-CNRS 7285 University of Poitiers PoitiersF-86022 Cedex France

The design and development highly efficient electrocatalysts for oxygen evolution reaction (OER) are critical for renewable energy generation. Ni-based electrocatalysts are widely used in the water electrolysis process. In this work, heterostructure consisting of selenides and layered double hydroxides (LDH) named (Co, Ni)Se4@NiFe-LDH, are prepared by an LDH-based strategy, in which the electronic structure of Ni active sites is regulated by interfacial electron interaction. The (Co, Ni)Se4@NiFe-LDH shows an optimized charge distribution of Ni sites and excellent catalytic activity. The effective charge modulation results in lowering the energy barrier of OOH* intermediate formation and adequate adsorption strength of the intermediates on Ni active sites, which improves the kinetics of OER. Specifically, the (Co, Ni)Se4@NiFe-LDH only requires an overpotential of 237 mV to reach the current density of 10 mA cm-2 under alkaline conditions. The results of this work demonstrate that reasonable engineering of heterostructure is an effective strategy to improve the intrinsic property of OER electrocatalysts for water splitting. © 2023, The Authors. All rights reserved.

关键词： Electrocatalysts

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Energy Storage: In Situ Fabrication of Hierarchically Branched TiO2Nanostructures: Enhanced Performance in Photocatalytic H2Evolution and Li–Ion Batteries (Small 47/2017)

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Small 2017年第47期13卷

作者： Guorui Yang Ling Wang Shengjie Peng Jianan Wang Dongxiao Ji Wei Yan Seeram Ramakrishna Department of Environmental Science & Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Mechanical Engineering National University of Singapore Singapore 117574 Singapore Jiangsu Key Laboratory of Materials and Technology for Energy Conversion College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

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