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Numerical Analysis on Solidification Behavior of Graphene Nanoplatelet Based Nanofluid in Cold Storage Cavity

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Journal of Thermal Science 2022年第4期31卷 1180-1193页

作者： CHEN Chen feng shiyu PENG Hao PENG Xiaotian LIU Weihua College ofAerospace Engineering Nanjing University ofAeronautics and Astronautics Nanjing 210016China Institute of Thermal Engineering Shanghai Maritime UniversityShanghai 201306China

Addition of graphene nanoplatelet(GNP)into water is a promising method for improving cold storage system performance,and its application requires comprehensive understanding of solidification behavior of GNP-water *** the present study,the influences of GNP mass concentration,cold storage cavity size and shape on solid-liquid interface evolution,temperature distribution,streamline profile as well as solidification rate are numerically *** enthalpy-porosity technique is adopted to track solid-liquid *** results show that the enhancement effect of GNPs on solidification is mainly reflected in the final stage in which heat conduction is predominant;the solidification occurs at the bottom of cavity in the early stage,and the solid-liquid interface is similar to the shape of cavity itself and then tends to be circular in the middle and final stages respectively;the reduction degree of solidification time reaches 30.1%at GNP mass concentration of 1.2 wt%under present simulation conditions;decreasing cavity size and adopting triangular cavity are beneficial for promoting the solidification,but they will suppress the enhancement effect of GNPs on solidification.

关键词： cavity shape graphene nanofluid phase change material solidification

Measurement of mass diffusion coefficients of O_2 in aviation fuel through digital holographic interferometry

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Chinese Journal of Aeronautics 2019年第5期32卷 1184-1189页

作者： Chaoyue LI Weihua LIU Xiaotian PENG Lei SHAO shiyu feng Key Laboratory of Aircraft Environment Control and Life Support of Ministry of Industry and Information Technology College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

The experimental apparatus to measure the mass diffusion coefficients of O2 in aviation fuel was constructed based on the digital holographic interferometry method. The theory of mass diffusion coefficient and interference image processing were introduced in detail. The accuracy of the experiment was verified by measuring the mass diffusion coefficient of 0.33 mol/L KCl in aqueous solution at 298.15 K. The mass diffusion coefficients of O_2 in RP3 and RP5 aviation fuels were measured at temperature from 278.15 K to 333.15 K, and the Arrhenius equation was employed to fit the experimental data. In terms of the Stokes-Einstein equation, the viscosities of these two aviation fuels were tested to estimate the correlation among mass diffusion coefficient, viscosity and temperature. A uniform polynomial calculation correlation was proposed to predict the mass diffusion coefficients of O_2 in both RP3 and RP5 aviation fuels, and its accuracy is considerably higher than that of the Stokes-Einstein equation.

关键词： Aviation fuel Diffusion coefficients Digital holographic interferometry Oxygen Viscosity

Theoretical study of ullage washing with mixed inert gas in a non-equilibrium state

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Chinese Journal of Aeronautics 2020年第12期33卷 3167-3175页

作者： shiyu feng Xiaotian PENG Lei SHAO Yan YAN Chen CHEN Weihua LIU Key Laboratory of Aircraft Environment Control and Life Support of MIIT College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China College of Aeronautics Chongqing Jiaotong UniversityChongqing 400074China College of Mechanical and Electrical Engineering Xi'an Polytechnic UniversityXi'an 710000China

The Mixed Inert Gas(MIG)produced by the novel Green On Board Inerting Gas Generation System(GOBIGGS)mainly consists of carbon dioxide,nitrogen and *** of the large solubility of carbon dioxide in jet fuel compared with nitrogen,the no gas release or equilibrium model could not be employed any *** this paper,first,a mathematical model of the ullage washing was set up to predict the variation of the oxygen concentration on ullage and in the fuel,and the gas evolution and dissolution rate were calculated by Fick's second ***,an experimental apparatus was constructed to verify the accuracy of the ***,the numerical comparisons of ullage washing using Nitrogen Enriched Air(NEA)and MIG are presented under various flow rates and fuel loads,and the result reveals that the variation of the oxygen concentration on ullage is nearly identical whatever the inert gas is NEA or ***,the variation of the oxygen concentration in the fuel is disparate,and the oxygen concentration decreases rapidly if the inert gas is MIG,especially when the fuel load is low or the flow rate of the inert gas is ***,MIG could suppress the rising trend of the oxygen concentration on ullage when the aircraft ascends if the fuel tank is fully washed into an equilibrium state on ground.

关键词： Inert gas Mixed inert gas Nitrogen enriched air Non-equilibrium Washing

Applications of membrane distillation technology in energy transformation process-basis and prospect

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Chinese Science Bulletin 2009年第16期54卷 2766-2780页

作者： WANG ZanShe GU ZhaoLin feng shiyu LI Yun School of Power and Engineering Xi'an Jiaotong University Xi'an 710049 China School of Human Settlement and Civil Engineering Xi'an Jiaotong University Xi'an 710049 China

Membrane distillation technology is a new type of efficient separation technology that combines traditional distillation technology and membrane separation technology. In the study, applications of membrane distillation technology in thermal engineering and refrigerating engineering with typical energy transformation process were presented. Desorption and regeneration process of saline solution by vacuum membrane distillation was proposed on the basis of the concentration and separation properties of membrane distillation. Membrane distillation technology could be used in lithium bromide absorption refrigeration system, energy storage system, and the regeneration process of liquid desiccant solution in temperature-humidity independent control air-conditioning system. The aim of the applications was to use the low-grade energy such as waste heat, solar energy and geothermal energy adequately and to improve the available temperature difference of heat source. According to latent heat transfer and thermal conduction across the membrane in direct contact membrane distillation process, a novel membrane heat exchanger with both heat transfer and mass transfer processes was proposed. The heat exchanger could be used as the solution heat exchanger of lithium bromide absorption refrigeration system and as the special heat exchanger that recovered heat and pure water simultaneously. Some feasible process flows about the applications of membrane distillation technology to energy transformation process were listed and analyzed. Finally, future research emphases were indicated.

关键词：蒸馏技术转换过程应用基础能源膜

Experimental comparison between aircraft fuel tank inerting processes using NEA and MIG

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Chinese Journal of Aeronautics 2018年第7期31卷 1515-1524页

作者： Lei SHAO Weihua LIU Chaoyue LI shiyu feng Chenchen WANG Jun PAN Key Laboratory of Aircraft Environment Control and Life Support of MIIT Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Aeronautics Chongqing Jiaotong University Chongqing 400074 China Jiangsu Province Key Laboratory of Aerospace Power System Nanjing Engineering Institute of Aircraft Systems Nanjing 210016 China

Fuel tank inerting technologies are able to reduce the fire risk by injection of inert gas into the ullage or fuel, the former called ullage washing and the latter fuel scrubbing. The Green On-Board Inert Gas Generation System（GOBIGGS） is a novel technology based on flameless catalytic combustion, and owning to its simple structure and high inerting efficiency, it has received a lot of attentions. The inert gas in the GOBIGGS is mainly comprised of CO2, N2, and O2（hereinafter, Mixed Inert Gas（MIG））, while that in the On-Board Inert Gas Generation System（OBIGGS）, which is one of the most widely used fuel tank inerting technologies, is NitrogenEnriched Air（NEA）. The solubility of CO2 is nearly 20 times higher than that of N2 in jet fuels,so the inerting capability and performance are definitely disparate if the inert gas is selected as NEA or MIG. An inerting test bench was constructed to compare the inerting capabilities between NEA and MIG. Experimental results reveal that, if ullage washing is adopted, the variations of oxygen concentrations on the ullage and in the fuel are nearly identical no matter the inert gas is NEA or MIG. However, the ullage and dissolved oxygen concentrations of MIG scrubbing are always higher than those of NEA scrubbing.

关键词： Dissolved oxygen Experiment Fuel tanks Inert gases Mixed Inert Gas(MIG) Nitrogen-Enriched Air(NEA) Oxygen

Ultralong Organic Phosphorescence of Triazatruxene Derivatives for Dynamic Data Encryption and Anti-counterfeiting

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Chinese Journal of Chemistry 2023年第18期41卷 2261-2268页

作者： Baoshuai Liang Wei An Jie Liu Yu Dong shiyu feng Weiguo Huang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China FuzhouFujian 350002China University of Chinese Academy of Sciences 19A Yuquan RoadBeijing 100049China

Comprehensive Summary,Organic luminogens with persistent room temperature phosphorescence(RTP)have drawn tremendous attentions due to their promising potentials in optoelectronic devices,information storage,biological imaging,and *** this work,six triazatruxene-based lumiogens with different peripheral substituents and configurations are synthesized and systematically *** results show that their fluorescence quantum yields in solid states range from 15.73%to 37.58%.Dispersing the luminogens as guest into the host(PPh_(3))could turn on the persistent RTP,where PPh_(3)acts as not only a rigid matrix to suppress the non-radiative transitions of the guest,but also provides energy transfer channels to the *** maximum phosphorescence efficiency and the longest lifetime could reach 29.35%and 0.99 s in co-crystal films of 6-TAT-CN/PPh_(3)and 5-TAT-H/PPh_(3),***,these host-guest co-crystalline films exhibit great potentials in advanced dynamic data encryption and *** work deepens the insight for low cost,halogen-free,and facile fabrication of all-organic persistent RTP materials.

关键词： Room temperature phosphorescence Host-guest systems Energy transfer Data encryption Anti-counterfeiting Fluorophores

Oxygen concentration variation in ullage influenced by dissolved oxygen evolution

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Chinese Journal of Aeronautics 2020年第7期33卷 1919-1928页

作者： shiyu feng Chaoyue LI Xiaotian PENG Tao WEN Yan YAN Rongjie JIANG Weihua LIU Key Laboratory of Aircraft Environment Control and Life Support of MIIT College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Building Services Engineering Hong Kong Polytechnic UniversityHong KongChina College of Mechanical and Electrical Engineering Xi'an Polytechnic UniversityXi'an 710000China

To determine the oxygen concentration variation in ullage that results from dissolved oxygen evolution in an inert aircraft fuel tank,the CFD method with a mass transfer source is applied in the present *** experimental system is also designed to evaluate the accuracy of the CFD *** dissolved oxygen evolution is simulated under different conditions of fuel load and initial oxygen concentration in ullage of an inert fuel tank with stimulations of heating and pressure *** increase in the oxygen concentration in ullage ranges from 0.82%to 5.92%upon stimulation of heating and from 0.735%to 12.36%upon stimulation of a pressure decrease for an inert ullage in the *** heating accelerates the release of the dissolved oxygen from the fuel by increasing the mass transfer rate in the mass transfer source and decreasing the pressure,thereby accelerating the dissolved oxygen evolution by increasing the concentration difference between the gas and the *** time constant that represents the oxygen evolution rate is independent of the initial oxygen concentration in ullage of an inert tank but depends closely on the fuel load,temperature and *** time constant can be fitted using a polynomial equation relating the fuel load to temperature in the heating stimulation with an accuracy of 4.77%.Upon stimulation of a pressure decrease,the time constant can be expressed in terms of the fuel load and the pressure,with an accuracy of 5.02%.

关键词： Computational Fluid Dynamics(CFD) Dissolved oxygen evolution Mass transfer Stimulation Time constant Volume of fluid

Methods for large reciprocating compressor capacity control: A review based on pulse signal concept

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Chinese Science Bulletin 2011年第19期56卷 1967-1974页

作者： GU ZhaoLin HOU XiongPo WANG ZanShe feng shiyu GAO Xiufeng LI Yun School of Human Settlements and Civil Engineering Xi'an Jiaotong University Xi'an 710049 China School of Energy and Power Engineering Xi'an Jiaotong University Xi' an 710049 China College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Large reciprocating compressors are important equipment used in a wide range of process industries. Most of these compressors have huge power requirements and their capacity often needs to be regulated. Advanced technologies in compressor capacity control are effective approaches for saving large amounts of energy in process industries. This paper reviews the basic theories and the state of the art of the capacity control technologies. In particular, a compressor working procedure is first presented using an analogy to the pulse signal concept. Compressor capacity control methods are classified into pulse frequency modulation and pulse amplitude modulation from a perspective of pulse signal processing. The mechanisms and feasibility of some important methods, including dead volume variable control, partial-stroke and full-stroke suction valve opening, are reviewed. Based on the pulse signal concept, a duty cycle regulation method for capacity control is introduced, and the performance and implementation of the new method are compared with those of the existing suction valve opening methods. The duty cycle regulation method has integrated advantages over the other methods in terms of regulating precision, pressure stability, energy saving and reliability. All the suction valve opening methods can cause gas reflux, resulting in the so-called breathing effect. The breathing effect has negative effects on regulation performance and compressor security, which needs further investigation in the future.

关键词：往复式压缩机脉冲信号处理容量控制基础脉冲幅度调制脉冲频率调制控制技术呼吸效应

Enhance the performance of polymer solar cells via extension of the flanking end groups of fused ring acceptors

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Science China Chemistry 2018年第10期61卷 1320-1327页

作者： shiyu feng Danyang Ma Liangliang Wu Yahui Liu Cai'e Zhang Xinjun Xu Xuebo Chen Shouke Yan Zhishan Bo Key Laboratory of Energy Conversion and Storage Materials College of Chemistry Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education Beijing Normal University State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology

Two new fused ring electron acceptors(FREAs)IDT-IC-T and IDT-IC-B with thienyl or phenyl substituents at the terminal INCN unit are *** calculations indicate that the two acceptors dominantly favor an intermolecularπ-πstacking between the flanking terminal *** twist angle between the aryl substituent and INCN unit has a significant influence on theπ-πstacking distance of terminal ***-IC-T with a smaller twist angle has a shorterπ-πstacking distance than that of IDT-IC-B with a larger twist *** addition,extending the conjugation also affects the blend film ***-IC-T and IDT-IC-B based photoactive films show appropriate nanoscale phase separations;whereas,blend films based on the parent compound IDT-IC show large-size acceptor *** expected,PBDB-T:IDT-IC-T blend films show higher and more balanced electron and hole ***,these two acceptors present a good charge-transport connectivity arising from the extended conjugation and the increased intermolecular ***,IDT-IC-T demonstrates the highest electron mobility(1.47×10^(-4)cm^2V^(-1)s^(-1))and the best power conversion efficiency(PCE)of 9.43%.As for IDT-IC,which only shows an electron mobility of 7.33×10^(-5)cm^2V^(-1)s^(-1)and a PCE of 5.82%.These findings provide a facile and effective way to improve the photovoltaic performance.

关键词： non-fullerene extended end groups high charge mobility polymer solar cells