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Experimental study on the submerged steam jet through side hole nozzle

IOP Conference Series: Materials Science and engineering 2015年第1期88卷

作者： W Wang F Yuan Q B Zhao D T Chong W X Chen J J Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 PR China

In this paper, the steam shape parameters and the condensation oscillation characteristics of the direct contact condensation of submerged steam jet into subcooled water were investigated through a side hole nozzle. Meanwhile, the dimensionless jet length and the expansion ratio versus pool water temperature and steam mass flux were obtained by measuring the photographs taken by a high speed camera. Both of them increased gradually with rise of pool water temperature and steam mass flux. A comparison of the shape parameters of three different style nozzles was also achieved. And a correlation of the dimensionless jet length was obtained, the predicted data agreed well with the experimental data, while the discrepancy was within ±5%. For the pressure oscillation versus steam mass flux, the peaks and the root mean square value of pressure oscillation were almost consistent in the range of 150-400 kgm-2s-1, while both of them increase in the range of 400-800 kgm-2s-1. The positive peak and negative peak were completely symmetrical.

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Numerical study on annular-mist flow in V-Cone meter for wet gas metering

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AIP Conference Proceedings 2014年第1期1592卷 121-129页

作者： Bofeng Bai Denghui He Rifeng Zhou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Increasing attention is paid on wet gas flow measurement with V-Cone meter in the production of natural gas. Annular-mist flow is a common flow regime in the wet gas flow metering. Knowledge of the annular-mist flow such as the distributions of the pressure, the droplet and the liquid film in the V-Cone meter is critical to improve the wet gas measurement model. In this paper, a numerical method based on a three-fluid closure model of film, droplet and gas was developed to simulate the annular-mist wet gas flow in the V-Cone meter. The method agreed well with the existing correlation and the relative error of simulation data is less than ±2.5%. The distributions of the droplet, liquid film and static pressure in a V-cone meter and the results on different flow conditions were simulated with the present method. The simulations showed that under the adjustment of the V-Cone element, the droplets moved in a straight path close to the wall after the throat section and a liquid jet was formed. It continues through the diffuser and reattaches to the wall. Some droplets will re-coalescence in the downstream of the V-Cone. It was found that little droplet was entrained in the back of the V-Cone, which was benefit for obtaining the low pressure. The results of the liquid film distribution showed that the liquid film thickness on the pipe wall and the cone body was affected by both the geometry of the V-Cone and the area and strength of the low pressure domain. The pressure in the low pressure domain decreased with the liquid and gas velocity increasing, and the gas-to-liquid viscosity ratio had little effects on the pressure distribution. The downstream low pressure port justifiably locates at six or more pipe diameters downstream of the cone back face for the present V-Cone meter.

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A three-dimensional geometric Monte-Carlo method for the simulation of light propagation in bio-tissue 3rd

A three-dimensional geometric Monte-Carlo method for the sim...

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International Conference on Computational Methods for Thermal Problems, ThermaComp 2014

作者： Zhang, Yong Chen, Bin Li, Dong Wang, Guo-Xiang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi710049 China Department of Mechanical Engineering The University of Akron AkronOH44325-3903 United States

ISBN: (纸本)9788874317271

A geometric Monte-Carlo (GMC) algorithm is proposed based on accurate calculation of optical transmission on the material interface for the simulation of light propagation in turbid media (e.g. bio-tissue). Grid is not necessary for the computation of photons' motion and the memory of optical parameters can be saved. Optical transmission is exactly simulated at material interfaces with curved boundary according to the principles of geometric optics, while energy deposition in different structures can be precisely counted. The validity of GMC method is confirmed by the comparison with voxels based Monte-Carlo method. Time consumed by GMC method is dramatically shortened compared with the hexahedral voxels based Monte-Carlo (VMC) method: about 25 times faster than VMC with a grid of 140× 140× 100 cells. In addition, the present GMC method shows better portability when raising the geometric complexity.

关键词： Monte Carlo methods

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Theoretical investigation on thermal responses of blood vessels to 595nm and 1064nm laser 3rd

Theoretical investigation on thermal responses of blood vess...

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International Conference on Computational Methods for Thermal Problems, ThermaComp 2014

作者： Li, Dong Chen, Bin Wu, WenJuan He, YaLing Wang, Guo-Xiang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi710049 China Department of Mechanical Engineering University of Akron AkronOH44325-3903 United States

ISBN: (纸本)9788874317271

As a kind of congenital vascular malformations, port wine stain is composed of ectatic venular capillary blood vessels buried within healthy dermis. In clinic, pulsed dye laser in visible band (e.g. 595nm) together with cryogen spray cooling have become the golden standard for treatment of PWS. However, due to the limited energy deposition of the PDL in blood, large blood vessels are likely to survive from the laser irradiation and complete clearance of the lesions is rarely achieved. Nd:YAG laser in near infrared 1064nm has deeper penetration depth in tissue, which has great potential in laser treatment of PWS. In this study, a multi-component bio-heat transfer model is developed to demonstrate the blood vessel thermal responses to two lasers. The results show that large and deeply buried blood vessels, which are likely to survive from 595nm laser irradiation, can be coagulated by 1064 nm laser. Meanwhile, the heating patterns within the vessel lumen for two lasers are also different. The 595 nm laser heated the superior portions of large blood vessels more than the inferior portions, while the 1064 nm laser produced uniform heating.

关键词： Blood vessels

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Secondary side flow field of steam generator with coupled heat transfer from primary to secondary side fluid

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2014年第8期48卷 1398-1405页

作者： Cong, Teng-Long Tian, Wen-Xi Qiu, Sui-Zheng Su, Guang-Hui Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The 3D flow characteristics in SG can provide input for the analysis of flow induced vibration (FIV). The secondary side flow field was simulated based on the porous media model with FLUENT solver. The flow resistances of flow along and cross tubes as well as flow resistances of downcomer, support plates and separators were added to the momentum equation. The 3D heat transfer from primary to secondary side fluid was calculated during iteration and set as the energy source of secondary side fluid, and the calculation results agree well with the design values. Meanwhile, the results show that the resultant localized thermal-hydraulic characteristics were unevenly distributed. The maximum and minimum flow vapor qualities flowing into the primary separators are 0.75 and 0.07, respectively. The average heat transfer coefficients of primary and secondary sides are 15 856.5 and 63 623.0 W/(m2·K), respectively. The maximum heat transfer coefficient of secondary side is 122 862.9 W/(m2·K). The average heat flux of U-tube is 149.9 kW/m2. The maximum cross flow velocity and cross flow energy (ρu2) through the U-bend region are 4.06 m/s and 1 145 J/m3, respectively.

关键词： Porous materials

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Sensitive detection of iodine by low pressure and short pulse laser-induced breakdown spectroscopy (LIBS)

Sensitive detection of iodine by low pressure and short puls...

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作者： Zhang, Xiaobo Deguchi, Yoshihiro Wang, Zhenzhen Yan, Junjie Liu, Jiping State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China Graduate School of Advanced Technology and Science University of Tokushima Tokushima 770-8501 Japan

In this study, Laser-Induced Breakdown Spectroscopy (LIBS) technology was applied to detect iodine, an essential element for human body. Iodine in buffer gases of N2 and air was detected using nanosecond and picosecond breakdowns of CH3I at reduced pressure. Compared with the conventional methods of iodine measurement, LIBS technology without sample preparation shows the merits of fast response, real-time detection and enhanced detection limit. The measurement results of iodine demonstrated that low-pressure LIBS is the favourable method for trace species measurement in analytical applications. The plasma generation processes of multi-photon ionization and electron impact ionization can be controlled by pressure and laser pulse width for the larger ionization and excitation processes of iodine, which was discussed by the intensity ratio of iodine emission at 183 nm to nitrogen emission at 174.3 nm. The detection limit of iodine measurement in N2 was 60 ppb in nanosecond breakdown at 700 Pa. Iodine in air as the buffer gas was also detected using nanosecond and picosecond breakdowns to examine the effect of oxygen. This journal is © the Partner Organisations 2014.

关键词： Impact ionization

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Simulation Investigation on the Dynamic Characteristics of a 600MW Supercritical Lignite-fired Pulverized Boiler

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Energy Procedia 2014年 61卷 1434-1437页

作者： Xiaoqu Han Zhaonan Xue Ming Liu Junjie Yan Jinshi Wang Daotong Chong Jiping Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The real-time dynamic simulation model of a 600MW lignite-fired pulverized boiler, which is a supercritical once-through boiler with fan mill three drying media direct fired system, was established. The step reduction of hot flue gas flow rate was simulated. The dynamic responses of live and reheat steam temperatures were obtained and analyzed. Results show that the response of steam temperature is an oscillation process. The superheat and reheat steam overtemperature values are influenced by the boiler load, the hot flue gas extracting percent and the inertia time of pulverizing system.

关键词： Simulation Dynamic Characteristics Hot Flue Gas Extracting Percent Steam Overtemperature

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Study on Steam-Water Solar Cavity Receiver

Study on Steam-Water Solar Cavity Receiver

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2014第四届国际新能源产业大会——主题：助力一个美丽、洁净、可持续发展的家园

作者： Jinjia Wei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Solar energy is clean without pollution,rich and free,so solar thermal power has the huge potential for future energy *** type concentrating technology can be used for large-scale solar power *** the power tower system,the heat receiver is the key equipment for sunlightheat *** thermal performance of the receiver will affect the efficiency of the entire power *** is no rich experience on the design of receiver,which is mainly based on the coal-fired *** to the non-uniform and instantaneous characteristics of sunlight,the receiver should differ greatly from the conventional coal-fired *** it is necessary to study the receiver according to the sunlight *** experiment platform for testing the thermal performance of a water/steam cavity receiver was firstly designed and *** start-up curves under different operating pressures were obtained and the receiver has low thermal efficiency of only about 55-70%.The low thermal efficiency is attributed to the low mass flow rate.A combined method was proposed to evaluate the thermal performance of the cavity receiver for start up and *** numerical results are in good agreement with the *** results suggested that an appropriate mass flow rate of 200 kg/h should be chosen for the design and operation of the experiment *** thermal performance of a solar cavity receiver under windy conditions was numerically *** heat flux and temperature distributions on boiling tubes in the cavity were *** convective and radiative heat losses were analyzed in *** the wind flow angle or velocity can obviously affect the air velocity inside the cavity,which reaches the maximum value for side on wind,resulting in a large convective heat *** on the experimental and numerical studies,a water/steam cavity receiver was designed and *** receiver is now being used in 1MW power tower plant in China with a

关键词： Study on Steam-Water Solar Cavity Receiver

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Thermodynamic Analysis on a Pre-dried Lignite-fired power System: Comparison on Energy Supply Systems for Dryer

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Energy Procedia 2014年 61卷 1424-1427页

作者： Ming Liu Junjie Yan Jinshi Wang Daotong Chong Jiping Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Pre-drying is a potential way to improve the electric generation efficiency of lignite-fired power plant, and steam is a main kind of drying heat source. In conventional pre-dried lignite-fired power system, the steam extraction of regenerative system is led to the dryer directly. The steam extraction must be used by the dryer after throttling, if the energy mismatch exists between the supply of steam extraction and the need of dryer. Two systems of energy supply for the dryer, that the energy of the steam extraction is supplied to the dryer via compressor or ejector, were proposed in this paper to further increase the energy utilization efficiency. These systems were thermodynamic analyzed, and the electric generation efficiencies of these systems were compared. The energy saving boundary was gotten.

关键词： Thermodynamics Lignite pre-drying Compressor Ejector

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Research on the two-phase flow and separation mechanism in the oil-gas cyclone separator

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IOP Conference Series: Materials Science and engineering 2015年第1期90卷

作者： L Z Wang X Gao J M Feng X Y Peng School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049China

The cyclone separator has attracted increasing attention due to its small size, rapid construction and high separation efficiency. This study investigated its gas-liquid two-phase flow and separation characteristics experimentally and numerically. A numerical model of two- phase flow in the cyclone separator was proposed using the Euler-Lagrange method. The distribution of pressure, tangential and axial velocity in the gas-phase flow field was obtained, and the oil droplet movement was traced. Separation efficiency was also studied experimentally, and the diameter distributions of oil droplets at the inlet and the outlet of the separator were measured by a Malvern laser particle size analyser to verify the simulation model. Based on high-speed photography technology, the oil film distribution and flow pattern on the wall of the cyclone separator were visualised. The variation of oil-gas two-phase flow in the cyclone separator was compared under various inlet flow rates. Based on the results, an improved structure was proposed, and the performance of the improved separator was investigated experimentally.

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