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Mechanism study and theoretical simulation on heat split phenomenon in dual-cooled annular fuel element

Annals of Nuclear Energy 2016年 94卷 44-54页

作者： Yangbin Deng Yingwei Wu Yuanming Li Dalin Zhang Wenxi Tian G.H. Su Suizheng Qiu State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an City 710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China

In this study, the mechanisms that cause heat split, a specific phenomenon in dual-cooled annular fuel elements, were investigated. On the basis of thermal resistance analysis, the developing process of heat split phenomenon was summarized. It was found that thermal expansion, fuel densification, swelling, creep, relocation and fission gas release are the original parameters driving the development of heat split. Due to these factors, thermal resistances for heat flux to internal and external channels change with the operating time, which results in heat split. Furthermore, the theoretical simulation on heat split was performed by FROBA-ANNULAR, which is a coupled thermal–mechanical analysis code for dual-cooled annular fuel elements. key parameters at different burnup stages, including gap size, gap conductance, temperature profile, coolant flux and heat flux were obtained. The calculation result shows that the fraction of heat flux to the internal cooling channel experiences complicated variation at the range of 32.9–39.7%. In addition, it was found that heat split does not match with the coolant split, especially at the lower burnup stage. Asymmetric heat transfer occurred because of the imbalance between heat split and coolant split, resulting in a substantial asymmetric temperature profile. Furthermore, heat split exerts an influence on DBNRs of inner and outer channels, although the computational values were still within the allowable limits.

关键词： Dual-cooled annular fuel Heat split FROBA-ANNULAR code MDNBR

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Laser-induced breakdown spectroscopy in Asia

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Frontiers of Physics 2016年第6期 226-250页

作者：王珍珍出口祥啓张臻臻王哲曾晓雁严俊杰 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Graduate School of Advanced Technology and Science Tokushima University State Key Lab of Power Systems Department of Thermal EngineeringTsinghua-BP Clean Energy CenterTsinghua University Wuhan National Laboratory for Optoelectronics (WNLO) Huazhong University of Science and Technology

Laser-induced breakdown spectroscopy(LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental *** has been extensively studied and developed due to the non-contact,fast response,high sensitivity,real-time and multi-elemental detection *** development and applications of LIBS technique in Asia are summarized and discussed in this review *** researchers in Asia work on different aspects of the LIBS study in fundamentals,data processing and modeling,applications and *** to the current research status,the challenges,opportunities and further development of LIBS technique in Asia are also evaluated to promote LIBS research and its applications.

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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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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%~±1..5%. For the two phase flow with low liquid content (LVF © 201., 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...

引用

1.th International Conference on Liquid Atomization and Spray Systems, ICLASS 201.

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 R1.4a 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. © 201. 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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201.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...

引用

24th IIR International Congress of Refrigeration, ICR 201.

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 {1. 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 {1. pressure gradient). EEI reflects the inherent energy efficiency properties of a heat exchanger, which represents the overall heat transfer coefficient per equivalent {1. pressure drop consumption. At a given temperature difference and fluid {1. rate, for the heat exchangers with the same heat transfer area and fluid {1. 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 {1. 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 {1. 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. © 201., Science Press. All right reserved.

关键词： Heat exchangers

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Specific Heat Ratio of High Methane Fraction Natural Gas/Air in Confined Vessel

Specific Heat Ratio of High Methane Fraction Natural Gas/Air...

引用

SAE 201. World Congress and Exhibition

作者： Tang, Chenglong Si, Zhanbo Zhang, Shuang Huang, Zuohua Pan, Shiyi Wang, Jinhua Gong, Jing Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an710049 China

The specific heat ratio used in heat release calculation plays an important role and the mass fraction burned is also a crucial parameter in thermodynamics analysis for engine combustion. A research of high methane fraction natural gas was investigated in a constant volume combustion vessel at different initial conditions. Results show that with the increase of the initial pressure, the specific heat ratio is decreased, and the time of the mixture burned up is postponed, while the peak heat release ratio is increased. With the increase of the methane fraction, the parameters have the opposite behavior. With the increase of the initial temperature, the specific heat ratio is decreased, and the time when the mixture is burned up is accelerated, and the peak heat release ratio has no obviously difference. With the increase of the dilution ratio or the CO2/N2 ratio, the specific heat ratio is decreased, and the peak heat release heat ratio is decreased. Meanwhile, the time of mixture burned up is postponed with the increase of dilute ratio or CO2/ N2 ratio. Copyright © 201. SAE International.

关键词： Specific heat

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