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Recent advances in nanoporous graphene membrane for gas separation and water purification

Science Bulletin 2015年第21期60卷 1807-1823页

作者： Chengzhen Sun Boyao Wen Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

Graphene is a one-atom-thick sheet of graphite comprising sp2-hybridized carbon atoms arranged in the hexagonal honeycomb lattices. By removing the honeycomb lattices and forming nanopores with specific geometry and size, nanoporous graphene has been demonstrated as a very high-efficiency separation membrane, due to the ultrafast molecular permeation rate for its one-atom thickness. This review focuses on the recent advances in nanoporous graphene membrane for the applications of gas separation and water purification, with a major emphasis on the molecular permeation mechanisms and the advanced fabrication methods of this state-of-the-art membrane. We highlight the advanced theoretical and experimental works and discuss the gas/water molecular transport mechanisms through the graphene nanopores accompanied with theoretical models. In addition, we summarize some representative membrane fabrication methods, covering the graphene transfer to porous substrates and the pore generation. We anticipate that this review can provide a platform for understanding the current challenges to make the conceptual membrane a reality and attracting more and more attentions from scientists and engineers.

关键词： Nanoporous graphene Gas separationWater purification Molecular permeationmechanism Membrane fabrication

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Prediction of thermal performance of radiative radial fin with temperature-dependent thermal conductivity using spectral collocation method

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Journal of Computational and Theoretical Nanoscience 2016年第9期13卷 5822-5831页

作者： Ma, Jing Sun, Ya-Song Li, Ben-Wen Key Laboratory of Shaanxi Province for Development and Application of New Transportation Energy School of Automobile Chang'an University Xi'an710064 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing102206 China Institute of Thermal Engineering School of Energy and Power Engineering Dalian University of Technology Dalian116024 China

Spectral collocation method (SCM) is developed to solve coupled radiation and conduction in radiative radial fin with temperature-dependent thermal conductivity and volumetric heat generation. In this approach, energy conservation equation is discretized by SCM, and a particular algorithm is proposed to alleviate the nonlinearity of energy conservation equation. Numerical results by SCM are compared with available results in the literature, which indicate that SCM can provide high accuracy for combined radiative and conductive heat transfer in radiative radial fin, and the integral averaged relative error decreases exponentially with the increasing number of collocation points. Meanwhile, the effects of various parameters on the thermal performance, such as dimensionless thermal conductivity coefficient, radiation-conduction parameter, dimensionless ambient temperature, dimensionless radiation sink temperature and dimensionless volumetric heat generation are also investigated. Copyright © 2016 American Scientific Publishers All rights reserved.

关键词： Fins (heat exchange)

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Influence of wettability on motion of compound droplets on solid surface in microchannel flow

Influence of wettability on motion of compound droplets on s...

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2016年大连国际微流控和芯片实验室大会

作者： Xinglong Shang Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

To understand droplet motion on solid surfaces is very important for many applications such as enhanced oil recovery（Freitas et al.2011）,droplet spreading,manipulation and fabrication of droplets in microfluidic devices（Worner et al.2012）.Solid surface wettability affects significantly the movement of the contact line and hence dominants the motion of droplets on solid surfaces,especially when the flow is confined to ***,the compound droplets are often common with the applications mentioned above（e.g.,water-in-oil-in-water and oil-in-water-in-oil type compound droplet）.Furthermore,the wettability of solid surfaces is often heterogeneous that make the drop motion more *** aim of this work is to investigate the influence of solid surface wettability（e.g.,solid surface wettability gradient and contact angle hysteresis） on the motion of compound droplets in microchannel *** this end,we develop a three-dimensional model by combining the front tracking method for drop surface motion and the generalized Navier boundary condition（Qian et al.2003） for contact line *** front tracking method to model the deformation and motion of compound droplets surrounded by elastic interfaces has been developed and validated in our previous work（Bai et al.2012;Luo et al.2015）.The presence of inner droplet significantly influences the deformation and motion of compound droplets on solid *** to the results from previous two-dimensional front tracking methods（Huang et al.2004） and other numerical methods（Ding et al.2010）,the pattern of ripples is observed in our simulations on the drop *** effects of dimensionless numbers including the Reynolds number,the capillary number and the volume ratio of the inner to the outer droplet are ***,it is demonstrated that the gradient of solid surface wettability and the hysteresis of contact angle have a remarkable effect on the deformation and motion of compound droplets.

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Movement of Oil-Water-Solid Three-Phase Contact Line under Velocity Gradients

Movement of Oil-Water-Solid Three-Phase Contact Line under V...

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2016年大连国际微流控和芯片实验室大会

作者： Wenxiu ZHENG Chengzhen SUN Bofeng BAI State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

The movement of three-phase contact line which formed in the oil-water-solid three-phase area is of great importance in a number of applications,such as oil recovery,groundwater remediation,decontamination and *** process of oil droplets/film migration and detachment,which are controlled by the moving contact line,has shown its great significance in oil *** are various factors which can drive the contact line to move,such as pressure and electrical driving forces,etc,which will generate a velocity gradient for the flow near the *** this paper,we dedicate to investigate the moving rule of contact line under a velocity gradient from molecular dynamics(MD) ***,MD simulations are implemented by the FORCITE module in the Material Studio software to obtain the microscopic view of the moving contact *** size of the system is about 14 nm×3 nm×50 nm,including 2880 oil molecules and 33080 water *** interatomic interactions are described by COMPASS force field,for which van der Waals interaction is described by 9-6 Lennard-Jones potential and electronic interaction is described by Coulombic potential *** water and oil molecules are arranged on a silica substrate and the velocity gradient is generated by moving the upper *** water molecules we used SPC/E *** cutoff radius is 1.25 nm to the short-range intermolecular *** long-range Coulombic interactions are handled with the Ewald *** on the MD simulations,the configuration of water and oil molecules shows us the morphology of the contact line and variations of the contact angle at different velocity *** results exhibit that the contact line will move only when the velocity gradient is larger than a certain *** force inside the contact line region such as friction force and shear stress are calculated to make a deep understanding of the moving contact *** property of water/oil molecules and velocity profile

关键词： Movement of Oil-Water-Solid Three-Phase Contact Line under Velocity Gradients Velocity

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Aqueous Synthesis of Ultrathin Platinum/Non‐Noble Metal Alloy Nanowires for Enhanced Hydrogen Evolution Activity

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Angewandte Chemie 2018年第36期130卷

作者： Zhaojun Liu Jing Qi Moxuan Liu Shumeng Zhang Qikui Fan Hongpo Liu Kai Liu Haoquan Zheng Yadong Yin Chuanbo Gao Frontier Institute of Science and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710054 China School of Chemistry and Chemical Engineering Shaanxi Normal University Xi'an Shaanxi 710119 China Department of Chemistry University of California Riverside CA 92521 USA

Although aqueous synthesis of nanocrystals is advantageous in terms of the cost, convenience, environmental friendliness, and surface cleanness of the product, nanocrystals of Pt and non‐noble metal alloys are difficult to obtain with controlled morphology and composition from this synthesis owing to a huge gap between the reduction potentials of respective metal salts. This huge gap could now be remedied by introducing a sulfite into the aqueous synthesis, which is believed to resemble an electroless plating mechanism, giving rise to a colloid of Pt‐M (M=Ni, Co, Fe) alloy nanowires with an ultrasmall thickness (ca. 2.6 nm) in a high yield. The sulfite also leads to the formation of surface M−S bonds and thus atomic‐level Pt/M–S(OH) interfaces for greatly boosted hydrogen evolution kinetics under alkaline conditions. An activity of 75.3 mA cm −2 has been achieved with 3 μg of Pt in 1 m KOH at an overpotential of 70 mV, which is superior to previously reported catalysts.

关键词： Dimetall-Legierungen Nanodrähte Platin Wasserstoffentwicklung Wässrige Synthesen

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The effects of Na+ and Cl- ions on the oil-water interface:a molecular dynamics study

The effects of Na+ and Cl- ions on the oil-water interface:a...

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2016年大连国际微流控和芯片实验室大会

作者： Boyao Wen Chengzhen Sun Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Ions at the oil-water interface is a ubiquitous phenomenon which plays a important role in many industrial processes,such as extraction separation,nanoparticle assembly,enhanced oil recovery,*** the petroleum industry,due to the long-term interaction with solids and crude oil,the water including formation water,injection water and aqueous solution dissolves lots of ions,such as Na,K,Ca,Mg Cl,SO,*** migration of charged ions in the bulk phase or interface between oil and water has a significant influence on the molecular packing of active species at the interface,zeta potential of oil droplets and microstructure and strength of interfacial film by changing the interfacial tension,interface viscosity and electrical repulsion of charged ganglia,thus affecting the stability of crude oil emulsions and the oil displacement in porous ***,more detailed knowledge of how ions affect the properties of oil-water interface is ***,we perform a molecular dynamics（MD） study on the effects of ions on the oil-water interface using the LAMMPS package in the NVT *** temperature of the system is kept at 300 K via Nose-Hoover *** simulation box,whose volume equals to4×4×11.4 nm,is divided into two layers of oil and water *** boundary conditions are applied in x-,y-and *** is adopted as the oil phase according to "equivalent alkane carbon number"（EACN） value of crude *** are arranged uniformly in the water *** and Clions are involved,because they are basic components of brine and quite common in the *** atomic interactions between decane molecules are described by the OPLS-AA potential while the TIP3 P model of water is adopted to consider both dispersive and electrostatic *** cut-off distance of all potentials is 10 *** results demonstrate that the structures and dynamics of the oil-water interface is significantly affected by Na and *** kosmotropes,Na ions remain strongly h

关键词： The effects of Na and Cl ions on the oil-water interface:a molecular dynamics study

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Multi-source driven capillary plane radiation air conditioning system

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AIP Conference Proceedings 2017年第1期1864卷

作者： Juanjuan Hu Mofeng Qu Huasheng Wang Shiyao Ni State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

A new absorption refrigeration system, which is driven by solar energy, biomass energy and geothermal energy simultaneously, was designed with capillaries as its radiation surface. Likewise, variations of water temperature in the capillaries with the change in both time and its flow rate were experimentally researched as well as how COP of the system varies with the surrounding temperature. The following conclusions have been obtained: Common refrigeration demand can be met by the system after its operation in 1 hour; with the increase in water flow rate in the capillaries, its temperature, which drops down after an increase, gets its peak value at the flow rate of 4.5-5.5 L/min; COP of the system decreases with the rise of surrounding temperature, thus it’s better to keep it from direct sunlight. With the utilization of natural energy and the structure of capillaries, the system’s advantages in simple structure, low cost, environment-friendly working process and nice performance lead to promising application prospects, especially in residence refrigeration in countryside.

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An experimental study of two-phase pressure drop of liquid nitrogen in circular horizontal channels 1

An experimental study of two-phase pressure drop of liquid n...

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1st International Conference IIR of Cryogenics and Refrigeration Technology, ICCRT 2016

作者： Chen, Xingya Zhang, Qiaoyu Xue, Rong Lai, Tianwei Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an China School of Energy and Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an China

ISBN: (纸本)9782362150173

Two-phase cryogenic flow are involved in many cooling systems. In order to study the mechanism of cryogenic two phase flow. Two-phase pressure drop of liquid nitrogen (LN2) in a circular horizontal channels was experimentally studied. A wide range of flow conditions: inlet pressure from 0.15 MPa to 0.30 MPa and mass flux from 120 kg/m2s to 320 kg/m2s, and tube diameters of 4 mm were performed in the experiment. The frictional pressure drop of two-phase LN2 in circular horizontal channel is estimated using two models, the homogeneous model and the separated flow model. In addition, the measured pressure drops are compared with those calculated from correlation models available for mini-scales. As a result, the homogeneous model with the Cicchitti et al. predict better than the other correlations mentioned in this study. © 2016, International Institute of Refrigeration. All rights reserved.

关键词： Two phase flow

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Three-dimensional positioning method for moving particles based on defocused imaging using single-lens dual-camera system

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Chinese Optics Letters 2016年第3期14卷 42-46页

作者：周骛金娜贾敏华杨荟楠蔡小舒 Institute of Particle and Two-Phase Flow Measurement/Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education Southeast University

A method to three-dimensional position moving particles with one lens and two cameras is proposed. Two par- ticle images with different degrees of defocusing are adopted to solve the ambiguous problem of particle positions. A single-lens dual-camera system is developed to simultaneously capture these two images for the moving par- ticles. The measurement principles and theoretical analysis are introduced first, and then simulated investiga- tions and experimental research are discussed. The measurement errors in the simulations and experiments are less than 1% and 4%, respectively, in 20 times the depth of field of the system, which validates the feasibility of this method.

关键词： Optics Physics

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Simulation on the flue gas pre-dried lignite-fired power plants firing high moisture lignite 29

Simulation on the flue gas pre-dried lignite-fired power pla...

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29th International Conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems, ECOS 2016

作者： Han, Xiaoqu Karellas, Sotirios Mu, Qiwei Liu, Ming Liu, Jiping Yan, Junjie Rakopoulos, Dimitrios Kakaras, Emmanuel State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Laboratory of Steam Boilers and Thermal Plants National Technical University of Athens 9 Heroon Polytechniou Street Zografou15780 Greece

ISBN: (纸本)9789616980159

The integration of flue gas fan mill dryer with an open pulverizing system significantly improves the plant thermal efficiency of the Flue Gas Pre-dried Lignite-fired power Systems (FPLPS). The aim of this article is to simulate the flue gas drying process applied for high moisture lignite and to find an optimal operation mode for various lignite compositions. A previously validated GSE simulation model of the FPLPS is used in the present work. Two types of lignite from China and Greece have been investigated as the feeding coal. The plant thermal efficiency of a 600 MW supercritical unit increases by 1.46 % at design case when the moisture content of lignite is being reduced from 39.50 % to 12 %. The improvement value reduces from 1.46 % to 1.19 % in water-cooled units and 1.39 % to 1.13 % in air-cooled units when the moisture content of Chinese raw lignite decreases from 39.50 % to 29.95 %. When Greek lignite is supplied, with moisture content varying from 53.20 % to 60 %, and lower heating value from 5.44 MJ·kg-1 to 6.31 MJ·kg-1, the plant thermal efficiency drops by a maximum value of 0.53 %, without considering the limited drying capacity of the pulverizing system. Moreover, two operational modes are compared in order to address the issues of fuel type variation, including the adjustment of the drying degree to maintain the boiler load, as well as the reduction of the boiler steam output. Case studies are presented to highlight the importance of the match between lignite pre-drying system and the boiler thermal system. Both the energy-saving potential and the flexibility to fuel type variations are concluded as the benefits of lignite flue gas pre-drying. © 2016 University of Ljubljana.

关键词： Flue gases

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