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Chaotic Characteristics Analysis on Recognition of Steam Plume flow Pattern of Direct Contact Condensation in a Rectangular Channel

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Energy Procedia 2017年 142卷 3827-3832页

作者： Binbin Qiu Jia Liu Jiping Liu Junjie Yan Xiaoping Yang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Chaotic characteristics of direct contact condensation(DCC) for steam jet in subcooled water in a rectangular channel were analyzed at subcooled water temperature of 30 ℃. The steam mass flux and Reynolds number of subcooled water were in the range of 250-600kg/(m 2 s) and 78,000-172,000 respectively. Three different flow patterns, bubble flow, oscillation jet and stable jet, were observed. Correlation dimension( D 2 ) changes with flow patterns. For bubble flow, oscillation jet and stable jet, the corresponding correlation dimension values increase and are in the ranges of 9.68~10.30, 10.03~11.17 and 11.10~12.62, respectively. Different flow patterns have different Hurst exponent( H ). From the range of correlation dimensions and Hurst exponents, the flow pattern of steam jet can be recognized without looking the picture of steam plume. This result is very important for flow pattern recognition without the observation windows.

关键词： flow pattern recognition chaotic characteristics correlation dimension Hurst exponent

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Experimental study on heat transfer to supercritical CO2 flowing in vertical upward tube at medium mass flux

Experimental study on heat transfer to supercritical CO2 flo...

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ASME 2017 Nuclear Forum, NUCLRF 2017, collocated with the ASME 2017 power Conference Joint with ICOPE 2017, the ASME 2017 11th International Conference on Energy Sustainability, and the ASME 2017 15th International Conference on Fuel Cell Science, engineering and Technology

作者： Zhang, Qian Li, Huixiong Kong, Xiangfei Zhang, Jun Lei, Xianliang Zhang, Weiqiang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'anShaanxi China North Carolina State University United States Burlington Laboratory 3144 North Carolina State University RaleighNC27607 United States

ISBN: (纸本)9780791840597

An experimental study was performed on heat transfer characteristics of supercritical pressure CO2 (SC-CO2) flowing at medium mass flux conditions in a vertically-upward tube of 16 mm inner diameter at the Heat Transfer and flow test loop of Supercritical CO2 (HTF-SCO2) in Xi’an Jiaotong University. Experimental parameters included the pressure ranging from 7.5 to10.5 MPa, the mass flux of 400-600 kg/m2s, and the heat flux of 20-100 kW/m2. Based on the experimental data, effects of mass flux, heat flux and operation pressure on heat transfer characteristics of SC-CO2 were thoroughly discussed. With the decrease of mass flux and increase of heat flux, heat transfer characteristics of SC-CO2 becomes worse and worse. The wall temperature rises to high levels with the occurrence of a wall temperature peak and the wall temperature peak also rises remarkably with the decrease in mass flux and increase in heat flux. Especially, effect of pressures on the heat transfer of SC-CO2 was found to be quite different from that previously reported in literature. When the heat flux is low (such as 30 kW/m2), the HTD was diminished with the increase in pressures, but when the heat flux is up to 50 kW/m2, the HTD is surprisingly intensified by the increase of pressure. The buoyancy effect was considered to explain this distinct influence of pressure on the heat transfer of SC-CO2 by employed a non-dimensional parameter Bu. With the increase of pressure, buoyancy effect was diminished owing to the decrease of density difference between fluids near the wall and the center. When heat flux was lower, the Bu was located between 5×10-6 and 10-4, where buoyancy effect impaired heat transfer, so the heat transfer coefficient increased by rising pressure. But when heat flux was larger, the Bu was above 10-4, where buoyancy effect began to enhance heat transfer, as a result, the heat transfer coefficient was reduced by weakened buoyancy effect because of the increase of pressure (CSPE). Copyrig

关键词： Heat flux

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Flame brush thickness of premixed turbulent flames: Hydrodynamic theory versus experiments 9

Flame brush thickness of premixed turbulent flames: Hydrodyn...

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9th International Conference on Modeling and Diagnostics for Advanved Engine Systems, COMODIA 2017

作者： Zhang, M. Patyal, A. Fogla, N. Wang, J.H. Huang, Z.H. Matalon, M. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States

The effect of varying turbulence intensities on the flame brush thickness is investigated numerically using a hybrid Navier-Stokes/front-tracking methodology in the context of the hydrodynamic theory. Two configurations, namely planar and Bunsen, are chosen with the latter used for direct comparison with experimental OH-PLIF Bunsen flame images. The Darrieus-Landau influences are controlled through the mixture Markstein length and the flame brush is analyzed under two regimes, sub- and supercritical based on the absence/presence of the hydrodynamic instability. In the planar configuration at low intensities, the sub-critical flame brush retains its near flat shape, while the super-critical flame brush forms a highly corrugated structure reminiscent of the cusped-like flames that result in the laminar setting. With increasing turbulence levels, these effects start to gradually diminish as the flame becomes dominated by velocity fluctuations arising from the turbulent field, finally leading to nearly identical behavior in both regimes for very high intensities. Unlike the planar flame, the sub-critical Bunsen flame surface is dominated by large wrinkles with a more rounded shape while the super-critical flame highlights the formation of cusp-like structures on its surface. Numerical verification of the Bunsen flame brush thickness shows a good qualitative match with experimental tests for turbulent CH4/air flames. The good agreement indicates the qualitative prediction capabilities of the hydrodynamic model. Copyright © 2017 by the Japan Society of Mechanical Engineers.

关键词： Navier Stokes equations

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The code development and thermo-hydrodynamic analysis of the reflood during severe accident in PWR

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Annals of Nuclear Energy 2017年 99卷 9-18页

作者： S.P. Niu Y.P. Zhang W.X. Tian S.Z. Qiu G.H. Su State Key Laboratory on Power Engineering and Multi-Phase Flow Xi’an Jiaotong University Xi’an 710049 China

The reflooding, i.e. injecting water to the uncovered degraded core, is the most important accident management measure to terminate a severe accident and to stop the core from being melt in LWR. The reflooding of LWR core during severe accident may lead to the core cooling and cessation or to the temperature escalation and further development of the accident. That will depend on several important parameters, characterizing the core state and the way of the reflooding. Appropriate understanding of the complex core reflooding phenomena is necessary for the prediction of the system evolution. Based on the reflood flow and heat transfer characteristics, a thermo-hydraulic analysis model for the reflood phase was developed and presented in this paper. Based on this model, a code module was developed for the thermo-hydraulic analysis of reflood. The calculation results for the different conditions are compared with the FLECHT data and the QUENCH data, respectively. The results showed that the calculation results and the experiment data are in substantial agreement. Then the influences of the system pressure, the subcooling of coolant and the wall temperature on reflood characteristics were studied, too. The quench velocity falls when the wall temperature went up. The quench velocity increases when the system pressure increases. The quench velocity drops with the increasing of water temperature. The paper also provides a theoretical basis for safety analysis of fuel element cladding during reflood phase.

关键词： Severe accident Reflood Thermo-hydraulic analysis Code development

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A comprehensive model for uniform heat flux inside cavity receiver with air-carbon mixture

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Energy Procedia 2017年 142卷 177-183页

作者： Yabin Jin Jiabin Fang Jinjia Wei Xinhe Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

Cavity receiver is one of the main components of efficient concentrating solar collector systems. It has the ability to operate at relatively higher temperature and efficiency. The safety and thermal efficiency of solar cavity receiver can affect the efficiency of the whole power system. However, the non-uniform distribution of heat flux and temperature inside the cavity tends to cause the operation instability and bring damage to the tube as well. In the present work, a comprehensive numerical model was developed by coupling Monte Carlo Ray Tracing (MCRT) and Finite Volume Method (FVM) to simulate the thermal performance of a 2D square solar cavity filled with air-carbon particle mixture. Firstly, the complicated photon transmission in the air-carbon particle mixture absorber is simplified as the transmission process in the statistically homogenous and isotropic turbid media. The solar heat flux distribution from the aperture to the wall is simulated by MCRT, and the photo-thermal convection process in the cavity receiver is modeled by FVM. Then the two parts are coupled in the cavity receiver by transferring the absorbed energy computed by MCRT to FVM, and this energy is applied as a source term of the energy equation in the FVM part. Based on this model, the temperature and heat flux characteristics of the cavity receiver were studied at various carbon densities. The result indicated that the air-carbon particle mixture can actively take part in the radiation and it appears that it has a remarkable effect on the temperature homogenization. It decreases the temperature of wall 3 dramatically and increases the temperature of wall 2 and wall 4. The relationships between the temperature unevenness and the number particle density were also analyzed. The temperature unevenness on the wall 3 drops most with the increase of number density of carbon particle, from 25.0K to 2.4K. The unevenness of temperature on the top and bottom walls also decreases slightly by 3K. In ad

关键词： solar cavity receiver non-uniform air-carbon particle mixture homogenization Monte Carlo ray tracing Finite volume method

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Influence of Oxy-fuel Atmosphere on Microscopic Physical-Chemical Properties of High-alkali Ash at Softening Temperature

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Energy Procedia 2017年 142卷 3240-3243页

作者： Chang’an Wang Hanqing Li Chenzhao Zhu Tao Han Yinhe Liu Lei Deng Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The utilization of high-alkali coals in Zhundong coalfield with oxy-fuel combustion technology has a great potential, however, the ash fusion properties of high-alkali coals are still unclear. Here, we studied the influence of oxy-fuel atmosphere on the microscopic properties of high-sodium ash. The change from air to oxy-fuel condition has a negligible influence on ash fusion temperatures, but exhibits certain impact on physical-chemical properties of high-alkali ash. Oxygen content presents a primary effect on the microscopic morphology of ash at softening temperature.

关键词： high-alkali coal oxy-fuel combustion CO 2 capture microscopic properties SEM

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Investigation on Heat Transfer Characteristics of the H-type Finned Tube in Flue Gas with High Content of Ash

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Energy Procedia 2017年 105卷 4680-4684页

作者： Tao Han Chang’an Wang Qi Cao Wufeng Chen Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

H-type finned tube is rarely used in waste heat recovery power generation stations, though it has an efficient heat transfer performance in large thermal power stations (WHRPGs, hereafter). To date, understanding of heat performance of H-type finned tube in WHRPGs is still lacked. The heat transfer characteristics of H-type finned tube in gas with high content of ash in WHRPGs was investigated in practical cement plant in present work. The actual ash deposition pattern was observed meanwhile. The characteristics of heat transfer process including heat transfer coefficient, heat effective coefficient, and flue resistance at gas velocity between 4.5 - 6.5 m·s –1 are obtained. Experimental results show that the heat transfer coefficient increases with gas velocity linearly, the heat effective coefficient nearly keep stable on the other hand, and serious ash-block problem occurs in flow area in the heat exchanger at the gas velocity of 4.5 - 6.5 m·s –1 . The max heat transfer coefficient remain below 10 w·m –2 ·k –1 , implying heat performance of H-type finned tube in WHRPGs is possibly inefficient.

关键词： H-type finned tube heat performance heat transfer

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Lithium–Sulfur Batteries: Flexible and High‐Loading Lithium–Sulfur Batteries Enabled by Integrated Three‐In‐One Fibrous Membranes (Adv. Energy Mater. 38/2019)

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Advanced Energy Materials 2019年第38期9卷

作者： Jianan Wang Guorui Yang Jie Chen Yunpeng Liu Yuankun Wang Cheng‐Yen Lao Kai Xi Duowen Yang Christopher J. Harris Wei Yan Shujiang Ding Ramachandran Vasant Kumar Department of Applied Chemistry School of Science MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter State Key Laboratory for Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an 710049 China Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Materials Science and Metallurgy University of Cambridge Cambridge CB3 0FS UK

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Excess thermodynamic properties and FTIR studies of binary of 1, 3-dichlorobenzene with alkyl acetates (C1–C5) at different temperatures

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Chemical Data Collections 2020年 29卷

作者： R. Raju S. Ravikumar R. Gerald Arokiaraj S. Karlapudi K. Sivakumar V. Pandiyan Department of Physics Nehru Memorial College (Autonoums) Puthanampatti 621 007Tamil Nadu India. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi 710049 P. R. China. Department of Chemistry S.V.Arts Degree & P.G.College (T.T.D'S) Tirupati 517502 A.P India

Densities ( ρ ) and speed of sound ( u ) have been reported for the binary mixtures containing 1, 3- dichlorobenzene (1, 3-DCB) with methyl acetate, ethyl acetate, propyl acetate, butyl acetate and pentyl acetate at four different temperatures ( T = 303.15, 308.15, 313.15 and 318.15 K) and at atmospheric pressure. The experimental data of densities and speeds of sound has been further utilized to calculate excess molar volume ( V m E ) and excess isentropic compressibility ( κ S E ) the excess properties have been fitted to Redlich-Kister equation. Further, V m E results have also been discussed by using Prigogine–Flory–Patterson (PFP). The experimental speeds of sound data in the present investigated mixtures were compared with various theoretical models like collision factor theory (CFT) and free length theory (FLT) to check their relative merits of pure component properties. Moreover, the experimental excess functions were correlated in terms of FTIR spectral analysis.

关键词： Binary mixtures Densities Ester Halogenated benzene Speed of sound FTIR

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Laser-induced Morphology Change and Photo-thermolysis of Gold Nano Particles with Application in Laser Dermatology

Laser-induced Morphology Change and Photo-thermolysis of Gol...

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2017第六届国际新材料大会

作者： Bin Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

Based on the principle of selective photothermolysis,laser photothermal therapy is regarded as the most effective treatment methodology for port-wine stain（PWS）,which is a congenital vascular malformation caused by the expansion of capillaries in the dermis.1064 nm Nd:YAG laser has great potential for the treatment of deeper and larger ***,the clinical effectiveness is limited because of the weak absorption of blood to Nd:YAG *** order to enhance the blood absorption,spherical gold nanoparticles were prepared by Sodium citrate reduction method with average size of 16.7 nm and absorbance peak at 522 *** nanorods were prepared by Seeded growth method and modified by PEG with average length and width of 79.1 nm and 13.5 *** this aspect ratio of 5.89,a strong absorption band at050 nm in the near-infrared range is *** can inject spherical gold particles into the bloodstream to enhance the light absorption of blood in visible range,while using gold nanorod to increase absorbance of blood to Nd:YAG Laser for improving the cure rate of laser treatment of vascular *** absorption was increased by 1.25 times for 581 nm（PDL laser） and 3.71 times for 1064 nm（Nd:YAG laser）.To investigate the morphology change and photothermolysis of gold NRs induced by Nd:YAG laser and obtain the optimal irradiation conditions for effectively destroying the vascular lesions,tissue-like phantoms were prepared and exposed to Nd:YAG laser with various laser parameters to investigate the photothermolysis of gold *** obtained the optimal photothermolysis of gold NRs for destroying the blood vessel as follows:When the concentration of gold NRs is 26.67 g/mL,the Nd:YAG laser energy density should be 40 J/cm2,with long laser pulse width of 0.3 ms for ten pulses.

关键词： Laser-induced Morphology Change and Photo-thermolysis of Gold Nano Particles with Application in Laser Dermatology

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