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第五届国际仿生工程学术大会(ICBE2016)

作者： H.X.Chen Y.Y Yan Jinliang Xu Linbin Huang The Beijing Key Laboratory on Multiphase Flow and Heat Transfer North China Electrical Power University Fluids & Thermal Engineering Research Group Faculty of EngineeringUniversity of Nottingham

The wettability of solid surfaces is very important to fundamental research and practical application. Inspired from species in nature a variety of bionic surfaces with super wettability have been fabricated by lithography, templating, plasma treatment and laser methods. Recent years, metal bionic materials used in heat transfer and their enhancement mechanism have been promising topics, for example superhydrophilic surface was used in boiling enhancement [1]dropwise condensation [2]and heat exchangers[3]and so on. But most metal superwettability surfaces used in heat transfer field were uniform while hybrid wetting substrates always were non-metal like silicon wafer. In this paper, the porous metal that involved in the hot applications was chosen as substrate. Superhydrophilic copper mesh(～0 o) and superhydrophobic copper mesh(～150 o) were fabricated by directly oxidation method and functionalization by trichloro(1 H, 1 H, 2 H, 2 H-perfluorooctyl) silane respectively, whose wettability can be interconverted by simple operation. After oxidation a layer of knife-like-flower oxide at thickness of 2μm covered the mesh lines. Closed to the substrate several knife sheets interdigitate together and disperse on the top, the gap between the knife sheets on the top of flowers is 100-200 nm. With functionalization by silane, mesh wettability converted from superhydrophilic into superhydrophobic, while, the knife-like flower layer has littler change but blunt edges. Then, a hybrid wettability mesh with inspired from Stenocara Beetle was prepared, which has circle superhydrophilic spots surrounded by hydrophobic background. The hybrid wettability mesh could be widely used in boiling enhancement, water harvesting, biological medicine and other practical applications.

关键词： copper mesh knife-like-flower hybrid wettability

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Mimicking the Stenocara Beetle——bumpy shell with hybrid wettability to harvest water by modified foam coppers

Mimicking the Stenocara Beetle——bumpy shell with hybrid we...

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第五届国际仿生工程学术大会(ICBE2016)

作者： H.X.Chen Y.Y.Yan The Beijing Key Laboratory on Multiphase Flow and Heat Transfer North China Electrical Power University Fluids & Thermal Engineering Research Group Faculty of EngineeringUniversity of Nottingham

For centuries, water has been a limited resource especially in arid regions, and nature has adapted to provide survival methods for species inhabiting. Stenocara beetles can collect water from morning fog using its bumpy shell, an array of hydrophilic bumps surrounded by hydrophobic background exactly. Dorrer et al, Lee et al and other researches studied kinds of patterned superhydrophobic and superhydrophilc surfaces to prove which bump surface has best water harvesting performance. Obviously, drainage, temperature difference, wind velocity, surface pattern et al are all key factors, but most samples in their studies are solid substrates with a layer microstructure. There are three common grounds:（1） with spraying of fluid almost condensate is blocked on the surface to form a film which weaken the effect of surface pattern to condensation process.（2） draining efficiency of condensate directly determines the performance of next generation, while, condensate mainly relies on gravity and flows away along the substrate surface at a low velocity,（3） more attention is focused on the microstructures on the surface with neglect of cooperation with macro scale of *** this paper, copper foam with the controllable pore structures is chosen to harvest water. After superhydrophilic and superhydrophobic treatments copper foam with hybrid wettability is fabricated with inspiring from the stenocara beetle. As previous reported porous metal with a superhydrophilic wettability could absorb a droplet away instantly, this can be used in the drainage system during water collection. Cooperating multi-layer cooper foams with different wettability and an independent drainage, a novel water collector is designed. When wind blows through the porous structure with less pressure decrease a droplet is generated on the surface of copper foam with certain temperature difference. Meantime, condensate is quickly sucked away by latter superhydrophilica foam then collected. At last, the eff

关键词： harvest water metal foam drainage

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Improved Measurement Characteristics of Elemental Compositions Using LaserInduced Breakdown Spectroscopy

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Spectroscopy (Santa Monica) 2016年第1期31卷 22-35页

作者： Wang, Z. Deguchi, Y. Katsumori, S. Ikutomo, A. Yan, J. Liu, J. Tainaka, K. Tanno, K. Watanabe, H. Kurose, R. Graduate School of Advanced Technology and Science State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Tokushima University Xi'anTokushima China Graduate School of Advanced Technology and Science Tokushima University Japan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China Key Laboratory of ThermoFluid Science and Engineering Xi'an Jiaotong University China Central Research Institute of Electric Power Industry Energy Engineering Research Laboratory Kanagawa Japan Department of Mechanical Engineering Kyushu University Fukuoka Japan Department of Mechanical Engineering and Science Kyoto University Kyoto Japan

Rapid detection of coal and fly ash is significant to improve the efficiency of thermal power plants and reduce environmental pollution. Given its fast response, high sensitivity, real-time, and noncontact features, laser-induced breakdown spectroscopy (LIBS) has a great potential for online measurement in these applications. The direct measurement of particles and gases using LIBS has been studied, and the method has been shown to be effective for this application.

关键词： Laser induced breakdown spectroscopy

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Thermodynamic Analysis on of Skid-Mounted Coal-bed Methane Liquefaction Device using Cryogenic Turbo-Expander

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IOP Conference Series: Materials Science and engineering 2017年第1期278卷

作者： Shuangtao Chen Lu Niu Qiang Zeng Xiaojiang Li Fang Lou Liang Chen Yu Hou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 PR China Xinjiang Coal Research Institute Urumqi 830091 PR China

Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is widespread but scattered, and the pressure, flow-rate and nitrogen content of CBM feed vary significantly. The skid-mounted liquefaction device is suggested as an efficient and economical way to recover methane. Turbo-expander is one of the most important parts which generates the cooling capacity for the cryogenic liquefaction system. Using turbo-expander, more cooling capacity and higher liquefied fraction can be achieved. In this study, skid-mounted CBM liquefaction processes based on Claude cycle are established. Cryogenic turbo-expander with high expansion ratio is employed to improve the efficiency of CBM liquefaction process. The unit power consumption per liquefaction mole flow-rate for CBM feed gas is used as the object function for process optimization, compressor discharge pressure, flow ratio of feed gas to turbo-expander and nitrogen friction are analyzed, and optimum operation range of the liquefaction processes are obtained.

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Influence of differential pressure fluctuation on flow measurement of gas-liquid two-phase flow in orifice plate

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2016年第10期37卷 2136-2141页

作者： Zheng, Xue-Bo Fan, Chen Che, Yu-Quan Bai, Bo-Feng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Oil and Gas Technology Institute of Changqing Oilfield Company Xi'an710021 China PetroChina Xinjiang Oilfield Branch Company Karamay834000 China

Differential pressure fluctuation is an inherent physical phenomenon in gas-liquid two-phase flow, which can be used to measure the quality and the whole flowrate. In order to study the influence of differential pressure fluctuation on gas-liquid two-phase flow metering for orifice plate, the differential pressure fluctuating processes under different flow conditions were measured, with the pressure ranging from 0.7 MPa to 1.0 MPa, the gas mass flow rate ranging from 200 kg/h to 400 kg/h, and the quality ranging from 0.4 to 1.0, respectively. The experimental results show that the mean value of the differential pressure and the standard deviation of the differential pressure could reflect changes of the flow parameters of the two-phase flow, whereas the standard deviation of the differential pressure is with poor repeatability. In the experiments, the repeatability of the standard deviation varied in the range of ±0.3%~±18.5%. For the two phase flow with low liquid content (LVF © 2016, Science Press. All right reserved.

关键词： flow measurement

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Numerical Study of Evaporation and Motion Characteristics of Liquid Nitrogen Droplet in High-Speed Gas flow

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IOP Conference Series: Materials Science and engineering 2017年第1期278卷

作者： Y. Ruan L. Chen X. Liu S. Chen Y. Hou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 PR China Xi'an Jiaotong University Suzhou Academy Suzhou 215123 PR China

In the cryogenic wind tunnel, cooling the circulating gas to cryogenic temperature by spraying liquid nitrogen (LN2) is an efficient way to increase the Reynolds number. The evaporation and motion of LN2 droplets in the high-speed gas flow is the critical process that determines the cooling rate, cooling capacity and the safe operation of the down-stream compressor. In this study, a numerical model of droplet motion and evaporation in high-speed gas flow is developed and verified against experimental data. The droplet evaporation rate, diameter and velocity are obtained during the evaporation process under different gas temperatures and flow velocities. The results show that the gas temperature has dominant influence on the droplet evaporation rate. High flow speed can increase droplet evaporation effectively at the beginning process. Evaporation of droplets with different diameters follows a similar trend. The absolute evaporation rate increases with the increase of droplet diameter while the relative evaporation amount is highest for the smallest droplet due to its high area-volume ratio. This numerical study provides insight for understanding the evaporation of LN2 droplets in high-speed gas flow and useful guidelines for the design of LN2 spray cooling.

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Temporal and spatial non-uniformity of surface heat transfer during r404a spray cooling in laser surgery 13

Temporal and spatial non-uniformity of surface heat transfer...

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13th International Conference on Liquid Atomization and Spray Systems, ICLASS 2015

作者： Wang, R. Zhou, Z.F. Chen, B. Bai, F.L. Wang, G.X. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China

Cryogen spray cooling has been applied to protect epidermis from thermal damage in laser dermatology. However, present cryogen R134a shows insufficient cooling capacity on minimizing the laser energy absorption by the melanin in darkly pigmented human skins. With lower boiling point, R404A has potential to improve the cooling capacity. This paper presents an experimental study on the temporal and spatial variation in surface temperature and heat flux during spray cooling using R404A by a straight tube nozzle with expansion chamber, which significantly improves the atomization effect. The experimental results indicate that the temporal and spatial conditions strongly influence the uniformity of surface heat transfer. There exists a sub-region of uniform cooling with radius of 2 mm around spray center with high transient heat flux above 400 kW/m2, which is conducive for physicians to control the therapy area precisely with enhanced laser energy. © 2015 International Conference on Liquid Atomization and Spray Systems. All rights reserved.

关键词： Laser surgery

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Influence of Geometrical Structure on Inertial Focusing of Particle in the Microchannel

Influence of Geometrical Structure on Inertial Focusing of P...

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2016年大连国际微流控和芯片实验室大会

作者： Liang-Liang Fan Hong Zhao Qing Yan Jing Guo Liang Zhao Jiang Zhe Fuli School of Food Equipment Engineering and Science(FEES) Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Department of Mechanical Engineering University of Akron

Particles subjected to the inertial lift force will be focused in several equilibrium positions in *** to now,most research on inertial focusing of particles have been focused on the microchannel with a constant cross-section,such as the straight *** study the influence of variable cross-section on the inertial focusing of particles in microchannel,three kinds of microchannels with different cross-sections including the gradually constricted,the constant,and the gradually expanded were designed and fabricated,where inertial focusing behavior of particles was investigated by *** result shows,in comparison with the microchannels with the constant and the gradually constricted cross-sections,7.32 um particles are focused in two symmetric streams with narrower bandwidth in the microchannel with the gradually expanded cross-section,indicating the gradually expanded geometrical structure is more efficient for the inertial focusing of ***,smaller secondary flow was generated at outlet of the microchannel with the gradually expanded cross-section,which is helpful for keeping the focused particle streams in a narrow *** further investigate the influence of the arrangement of the gradually expanded cross-section on the inertial focusing of particles,a series of gradually expanded geometrical structures arranged on one side,symmetrically arranged on two sides,and asymmetrically arranged on two sides of the microchannel were designed,*** on inertial focusing of particles were conducted using7.32 um and 9.9um particles,showing particles are focused in one or two streams in the microchannels with gradually expanded geometrical structures arranged on one side or symmetrically arranged on two sides while particles are focused in two or three streams in the microchannel with gradually expanded geometrical structures asymmetrically arranged on two *** it can be obtained that to achieve one-stream inert

关键词： Influence of Geometrical Structure on Inertial Focusing of Particle in the Microchannel

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Numerical simukation of nitrogen condensation flow in acryogeni nozzle 24

Numerical simukation of nitrogen condensation flow in acryog...

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24th IIR International Congress of Refrigeration, ICR 2015

作者： Wan, Sun Guoqing, Liu Lu, Niu Shuangtao, Chen Yu, Hou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 China

ISBN: (纸本)9782362150128

2-D numerical simulations on the nitrogen expansion flow with spontaneous condensation in a nozzle were conducted based on the equilibrium model and the non-equilibrium model respectively. In the equilibrium model, the mass transfer between the liquid and vapor is determined by the saturation enthalpies of the liquid and vapor phases. The pressure distribution of the nozzle could be influenced slightly by the condensation process. In the non-equilibrium model, the classical nucleation model is used for the droplets formation. The flow is heated by the latent heat and consequently the decrease of pressure and the increase of Mach number are delayed. Meanwhile, due to the requirement of a certain supercooling level, the condensation onset point is pushed away from the nozzle inlet, and the nozzle outlet wetness fraction becomes smaller. Then, the influence of the nozzle inlet temperature and inlet pressure on gas supercooling, nucleation rate and wetness are analyzed.

关键词： Nucleation

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Energy efficiency evaluation method for plate heat exchanger

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Kexue Tongbao/Chinese Science Bulletin 2016年第8期61卷 802-808页

作者： Zhang, Yanfeng Jiang, Chen Shou, Binan Zhou, Wenxue Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Technology Service Center CO. LTD Beijing100011 China LanZhou Guanyu Heat Transfer and Energy Saving Engineering and Technology Research CO. LTD Lanzhou730050 China

In heat exchangers, heat transfer between the cold and the hot fluid consumes pumping power. Evaluating the energy efficiency of this process scientifically and quantitatively is an urgent issue for both academic research and industrial applications, and has important significance to energy saving and emission reduction. We comprehensively analyzed the flow and heat transfer characteristics of water-water heat transfer process without phase-change in a heat exchanger, and proposed the energy efficiency index (=k/pn, k is overall heat transfer coefficient and p is flow pressure gradient). EEI reflects the inherent energy efficiency properties of a heat exchanger, which represents the overall heat transfer coefficient per equivalent flow pressure drop consumption. At a given temperature difference and fluid flow rate, for the heat exchangers with the same heat transfer area and fluid flow length, bigger EEI means a lager heat transfer rate per equivalent pumping power consumption. EEI is independent on the heat transfer area;no dependence or weak dependence on the flow velocity can be achieved by choosing the index n reasonably, indicating a good stability of EEI. Evaluation result based on national standard of heat exchanger performance test measured could represent the energy efficiency of the heat exchanger. Combined with the water-water heat transfer process without phase-change flow and heat transfer performance database of the plate heat exchangers, the value of index n and the overall EEI distribution of plate heat exchangers in industry are obtained, providing a basis for the classification of the energy efficiency of plate heat exchangers. © 2016, Science Press. All right reserved.

关键词： Heat exchangers

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