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作者： Zhang, Liang Li, Zhen-Dong Li, Kai Li, Hui-Xiong Zhao, Jian-Fu Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi710049 China Beijing102209 China

Numerical simulation of single bubble pool boiling process including transient thermal response of solid wall is performed using the ghost fluid method and the level set method for the sharp interface representation. The results show that non-physical initial condition in the numerical simulation deeply affects the process of bubble growth, and then multi-cycle simulation is necessary to eliminate its influence. It is shown by the present results that two nucleate criteria, i.e. constant waiting time and constant nucleate superheat, for determining the appearance time for the subsequent bubble lead to the same quasi-steady process of bubble growth if they are matched with each other. A periodically expanding and receding thermal "hollow" can be observed inside solid wall underneath the growing bubble. The recovery of the temperature on the nucleate site and the thermal boundary layer near the heating surface is influenced by transient heat conduction inside solid wall, which can affect evidently bubble thermal dynamics and heat transfer.

关键词： Numerical methods

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Development and application of a coal combustion life cycle on-line monitoring system

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Energy engineering: Journal of the Association of Energy engineering 2015年第1期112卷 28-46页

作者： Liu, Haiyu Tan, Houzhang Xiong, Xiaohe Ma, Lin Miao, Yang Xu, Tongmo Taiyuan University of Technology 030024 China Xi'an Jiaotong University Xi'an710049 China Electric Power Research Institute Co. Ltd Beijing100069 China School of Process Environmental and Materials Engineering Centre for Computational Fluid Dynamics University of Leeds LS2 9JT United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In China, coal quality fluctuates and deviates greatly from the original design in many large-scale coal-fired power plants. To maintain a secure level and combustion efficiency, a "coal combustion life cycle online monitoring system" (CLMS) has been developed and installed on a 215MW boiler in China. Ten temperature detectors have been installed at the heights of three-layer burners along the furnace. To improve the accuracy of measuring unburnt carbon in fly ash, an adjustable microwave test facility was established. An on-line measurement device for unburnt carbon in ash has been newly developed and attached to the convection flue gas pass. To optimize combustion processes, a real-time neural network prediction model for coal calorific value has been developed. By calculating and analyzing the data in computer workstations, safety evaluation of burner ignition, economic analysis and energy loss analysis can be obtained in real time. As for fluctuation in coal quality, application of the system has improved boiler efficiency more than 1.0%, and reduced NOx by 10-15%. © Copyright Association of Energy Engineers (AEE).

关键词： Life cycle

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Novel method for simultaneous measurement of film thickness and mass fraction of urea–water solution

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Chinese Optics Letters 2014年第12期12卷 133-136页

作者：杨荟楠郭晓龙苏明旭蔡小舒 School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai Key Laboratory of Multiphase Flow and Heat transfer in Power Engineering University of Shanghai for Science and Technology

Quantitative knowledge of the film thickness and mass fraction of the urea-water solution is very crucial in many practical applications. Film thickness or mass fraction can only be determined individually by conventional measurement techniques. We develop a novel measurement method to measure the film thickness and mass fraction of ure^water solution simultaneously. The absorption coefficients of urea-water solution （5 50 wt%） are measured, a pair of optimized wavelengths is then chosen to achieve high measurement sensitivity. Cross validation is also performed and uncertainties of the technique are smaller than 0.68% for thickness measurements and 1.86% for mass fractions.

关键词： Film thickness Metabolism Thickness measurement Uncertainty analysis Urea Water absorption

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Rheological characteristics of CTAC aqueous solutions under the combined effects of shearing and temperature

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2014年第2期35卷 278-281页

作者： Xu, Na Wei, Jin-Jia State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The rheological properties of CTAC/NaSal aqueous solutions (NaSal had same molarity with CTAC.) with different concentrations were experimentally investigated at different temperatures ranging from 10°C to 70°C and different shear rates from 1 s-1 to 300 s-1. There were a critical shear rate and a critical temperature for all measured surfactant aqueous solutions with mass concentrations ranging from 0.001% to 0.015%. The effects of temperature and shearing on viscosity properties of surfactant solution varied with the concentration. Rheological characteristics of viscosity showed complex variations under the combined effects of temperatures and shearing even for the solutions with same concentration. Surfactant solution with relatively high concentration thickened for the second time when suffering from strong shearing and high temperature.

关键词： Temperature

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Effects of the turbulence and drag force on heat transfer characteristics in supercritical water fluidized bed

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2014年第12期35卷 2437-2441页

作者： Lü, You-Jun Dong, Xu-Bin Zhang, Tian-Ning State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The Eulerian two-fluid model based on Kinetic Theory of Granular flow was used to investigate the effects of the turbulence and drag force on heat transfer characteristics in supercritical water fluidized bed in this paper. Three drag models including Gidaspow, Syamlal-O'Brien and Wen-Yu drag models, and four turbulence models that are three high Renolds number turbulence model: standard κ - Ε, RNG κ - Ε, realizable κ - Ε and a low Renolds number turbulence model, are adopted. The results show that the Gidaspow drag model is the most proper drag model in SCW fluidized bed among three models employed. As for the four turbulence models, the bed-to-wall heat transfer coefficients simulated with the three high Renolds number turbulence models are in a good consistency, and are all larger than that simulated with the low Renolds number turbulence model. RNG κ- Ε turbulence model is the most proper one for the simulation of heat transfer characteristics in SCW fluidized bed with comprehensive considerations. © 2014, Science Press. All right reserved.

关键词： Fluidized beds

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Shock tube study on ignition delay of multi-component syngas mixtures - Effect of equivalence ratio

Shock tube study on ignition delay of multi-component syngas...

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作者： Thi, Luong Dinh Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China Le Quy Don Technical University Hanoi Viet Nam

Ignition delays were measured in a shock tube for syngas mixtures with argon as diluent at equivalence ratios of 0.3, 1.0 and 1.5, pressures of 0.2, 1.0 and 2.0 MPa and temperatures from 870 to 1350 K. Results show that the influences of equivalence ratio on the ignition of syngas mixtures exhibit different tendency at different temperatures and pressures. At low pressure, the ignition delay increases with an increase in equivalence ratio at tested temperature. At high pressures, however, an opposite behavior is presented, that is, increasing equivalence ratio inhibits the ignition at high temperature and vice versa at intermediate temperature. The affecting degree of equivalence ratio on ignition delay is different for each mixture at given condition, especially for the syngas with high CO concentration. Sensitivity analyses demonstrate that reaction H + O2 = O + OH (R1) dominates the syngas oxidation under all conditions. With the increase of CO mole fraction, reactions CO + OH = CO2 + H (R27) and CO + HO2 = CO2 + OH (R29) become more important in the syngas ignition kinetics. With the increase of pressure, the reactions related to HO2 and H 2O2 play the dominate role. The opposite influence of equivalence ratio on ignition delay at high- and intermediate-temperatures is chemically interpreted through kinetic analyses. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Shock tubes

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Experimental study on the submerged steam jet through side hole nozzle

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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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