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Hydrogen production from co-gasification of coal and biomass in supercritical water by continuous flow thermal-catalytic reaction system

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 327-330页

作者： YAN Qiuhui GUO Liejin LIANG Xing ZHANG Ximin State Key Lab of Multiphase Flow in Power and Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Environmental and Municipal Engineering Xi'an University of Architecture and TechnologyXi'an 710055China State Key Lab of Multiphase Flow in Power and Engineering Xi'an Jiaotong UniversityXi'an 710049China

Hydrogen is a clean energy *** abundant coal sources and green biomass energy into hydrogen effectively and without any pollution promotes environmental *** co-gasification performance of coal and a model compound of biomass,carboxymethylcellulose (CMC)in supercritical water (SCW),were investigated *** influences of temperature,pressure and concentration on hydrogen production from co-gasification of coal and CMC in SCW under the given conditions (20-25 MPa,650℃,15-30 s) are discussed in *** experimental results show that H2,CO2 and CH4 are the main gas products,and the molar fraction of hydrogen reaches in excess of 60%.The higher pressure and higher CMC content facilitate hydrogen production;production is decreased remarkably given a longer residence time.

关键词： hydrogen production coal CMC supercritical water co-gasification

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Wire‐Mesh Capacitance Tomography in Gas‐Liquid flows

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AIP Conference Proceedings 2007年第1期914卷 710-716页

作者： Shan‐Fang Huang Xiu‐Gang Zhang Dong Wang Zong‐Hu Lin State Key Lab. of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

A new intrusive, wire‐mesh capacitance tomography for phase distributions in horizontal pipes is presented. A wire with an insulating film is used as a capacitor. The capacitance is in direct proportion to water film thickness, independent of water distribution and the salinity. We can obtain film thickness by measurement of capacitance. The sensor consists of four parallel wire capacitors, vertically placed over the cross section of the pipe. The interface is the result of linking the discrete film thicknesses with smooth curve, which are the tomographic result only when both phases are continuous. Static and dynamic experiments were carried out in air‐water two‐phase flows in horizontal pipes, from which we analyze the disturbance factors of the sensor to the flow field and measurement error of film thickness. The experimental results show that the tomographic results are consistent with expectation. The method has several advantages of no reconstructed algorithms, high signal‐to‐noise ratio, high sensitivity, and high spatio‐temporal resolution. The disturbance and error can be neglected in the range of this paper.

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multiphase flow Measurements by Full Stream Batch Sampling

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AIP Conference Proceedings 2007年第1期914卷 165-171页

作者： Dong Wang Fa‐Chun Liang Xiu‐Gang Zhang Zong‐Hu Lin State Key Lab. of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

A new method of multiphase flow measurements that based on the “extracting and separating method” was proposed in this paper. An extraction flow (or sample) is diverted in a manner of time sharing or full stream batch sampling, then the sample is separated into single phase flows and metered with conventional flow meters, the total flow rates of each phase are determined according to the metered values and the extraction ratios. Because the full stream is conducted to the extraction loop during sampling, no matter what the flow regime of multiphase flow is, the extracted stream (or sample) is always the representative of the total stream and the extraction ratio can keep stable. Experiments were conducted in an air‐water‐oil flow test loop, the inside pipe diameter of the test loop was 50 mm, and the superficial gas velocity varied from 4.5 m/s ∼22m/s, the liquid superficial velocity was in the range of 0.02∼0.3m/s, the oil concentration was in the range of 0.0%∼60% by volume. The flow pattern occurring during the experiments included stratified flow, wave flow and annular flow. The experimental results shown that the full stream batch sample method is feasible to measure the multiphase flow rate, and the average error of flow rates measurements for each phase was less than 3.82%.

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Two dimensional numerical simulation of tapered pulse tube refrigerator

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2006年第2期27卷 199-201页

作者： Zhao, Chun-Feng He, Ya-Ling Ding, Wen-Jing Yang, Wei-Wei Tao, Wen-Quan State Key Lab. of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Two-dimensional numerical simulation of the viscous compressible oscillating flow was carried out for the uniform cross-section and tapered pulse tubes by using a compressible SIMPLEC algorithm code developed by the authors. Effects of the taper angle on the performance of the pulse tube refrigeration were studied. The results showed that there was an optimum taper angle for tapered pulse tube refrigerator. With this optimum taper angle, the refrigerator performance can be improved a lot. But when the taper angle becomes larger than the optimum value, the cooling performance becomes inferior to that of the circular tube. The inherent mechanism of how the tapered pulse tube affects the performance of pulse tube refrigerator was also studied from the view point of second flow distribution in the pulse tube. Compared to the uniform cross-section pulse tube, the values of second flow in tapered pulse tube change a lot and the distribution of second flow becomes uneven as well. This is the main reason that the performance of tapered pulse tube can be improved compared to uniform cross-section pulse tube.

关键词：锥形脉管二次流数值研究

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HYDRODYNAMIC RESISTANCE EFFECT OF FLUID LAYER BETWEEN TWO IMMERSED APPROACHING PARTICLES

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China Particuology 2006年第5期4卷 220-228页

作者： Yanpeng Li Bofeng Bai School of Environmental Science and Engineering Chang'An University Xi'an 710064 P.R. China State Key Lab of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 P.R. China

A three-dimensional direct simulation of an immersed solid particle approaching another particle, or a flat wall, is conducted to investigate the mechanics of hydrodynamic impact of immersed particles. The simulation method is based on a modified immersed boundary method using a fixed grid system. When the particle separation distance becomes smaller than grid spacing, to account for the hydrodynamic resistance effect of liquid layer between particles near contact, a microlayer model is developed to allow determination of the pressure profile within the micro-layer without neglecting the inertial force of the layer flow. The pressure force is then taken into account in equation of particle motion. Comparisons of the simulation results with the experimental results reported in the literature are shown to substantiate the model presented in this study. The simulations reveal the complex three-dimensional flow field of the liquid and the motion of the approaching particle. The fluid pressure in the gap caused by the unsteady motion of the particle is significantly increased when the separation distance of particles is less than about one-tenth diameters of particle. Therefore the velocity of approaching particle starts to decrease due to the hydrodynamic resistance force at this position.

关键词： direct simulation microlayer model immersed boundary method hydrodynamic resistance effect

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Measurement of saturated liquid density of dimethyl ether

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2006年第5期27卷 748-750页

作者： Wu, Jiang-Tao Wang, Bin Yuan, Le-Ming Liu, Zhi-Gang State Key Lab of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A new vibrating tube densimeter was developed with a precision of better than ±0.5 kg/m3. Using this apparatus, the saturation liquid density of dimethyl ether was measured from 233.15 K to 320.15 K, and the max relative expanded uncertainty was 0.34%(coverage factor k = 2). The experimental data of this work were correlated as a polynomial function of the temperature with the published data of our previous work. The average and maximum relative deviation were 0.13% and 0.37%, respectively.

关键词： Dimethyl ether Saturation liquid density Vibrating tube

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Experimental study on dryout point in vertical narrow annulus under low flow conditions

Experimental study on dryout point in vertical narrow annulu...

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12th International Conference on Nuclear engineering (ICONE12) - 2004

作者： Tian, Wenxi Myint, Aye Li, Zhihui Qiu, Suizheng Su, G.H. Jia, Dounan State Key Lab. Multiphase Flow P.E. 710049 Xi'an China State Key Lab. Multiphase Flow P.E. Sch. of Energy and Power Engineering Xi'An Jiaotong University 710049 Xi'an China

Prediction of dryout point is experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annular with narrow gap is bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux from 26.6 to 68.8 kg/m2 s and wall heat flux from 5.0 to 50.0 kW/m2. The location of dryout is obtained by observing a sudden rise in surface temperature, Kutateladze correlations is cited, however proved to be not a proper one for annuli gap and modified to predict the location of dryout. Considering in detail the effects of the geometry of annuli, pressure, mass flux and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annular gap under low flow condition which has a good agreement with experimental data.

关键词： Two phase flow

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Combustion characteristics and heat release analysis of a compression ignition engine operating on a diesel/methanol blend

Combustion characteristics and heat release analysis of a co...

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作者： Huang, Z.H. Lu, H.B. Jiang, D.M. Zeng, K. Liu, B. Zhang, J.Q. Wang, X.B. State Key Lab. Multiphase Flow P.E. Xi'an Jiaotong University Xi'an China Sch. of Energy and Power Engineering Xi'an Jiaotong University Xi'an China State Key Lab. Multiphase Flow P./E. Inst. of Internal Combustion Engines Xi'an Jiaotong University Xi'an 710049 China

A stabilized diesel/methanol blend was developed and the combustion characteristics and heat release analysis of this blend was carried out in a compression ignition engine. The study showed that the increase in the methanol mass fraction will result in an increase in the heat release rate in the premixed burning phase and shorten the combustion duration of the diffusive burning phase. Ignition delay increases with the increase in the methanol mass fraction and the behaviour is more obvious at low engine load and high engine speed. The rapid-burn duration varies little with the methanol mass fraction and the total combustion duration decreases with the increase in the methanol mass fraction. At a low engine speed, the centre of heat release curve tends to be close to the top dead centre (TDC), with an increase in the methanol mass fraction at all engine loads and fuel delivery advance angles, the maximum rate of pressure rise and the maximum rate of heat release increase with the increase in the methanol mass fraction. At a high engine speed, the centre of the heat release curve closes to TDC at high engine load and will depart from TDC at low engine load. The maximum rate of pressure rise and heat release gives an increasing trend with the increase of methanol mass fraction at high engine loads. The maximum cylinder pressure increases with the increase of the methanol mass fraction. The presence of oxygen reduces the peak pressure, but the reduction was found to be insensitive to the proportion of oxygen within the 6-11 per cent range of testing.

关键词： Combustion

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Engine performance and emissions of a compression ignition engine operating on the diesel-methanol blends

Engine performance and emissions of a compression ignition e...

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作者： Huang, Z.H. Lu, H.B. Jiang, D.M. Zeng, K. Liu, B. Zhang, J.Q. Wang, X.B. State Key Lab. Multiphase Flow P. Xi'An Jiaotong University Xi'an China Sch. of Energy and Power Engineering Xi'An Jiaotong University Xi'an China Coll. of Ener. and Power Engineering Inst. of Internal Combustion Engines Xi'An Jiaotong University Xi'an 710049 China

A stabilized diesel-methanol blend was realized and a study on the performance and emissions of the diesel-methanol blend was carried out in a compression ignition engine. The study showed that the engine thermal efficiency increases and the diesel equivalent b.s.f.c. decreases with increase in the oxygen mass fraction (or methanol mass fraction) of the diesel-methanol blends due to an increased fraction of premixed combustion phase, oxygen enrichment and improvement in the diffusive combustion phase. Further increase in the fuel delivery advance angle will achieve a better engine thermal efficiency when the diesel engine is operated using the diesel-methanol fuel blends. A marked reduction in the exhaust CO and smoke can be achieved when operating with the diesel-methanol blend. There is not a large variation in the exhaust hydrocarbon with the addition of methanol in diesel fuel. NOx increases with increase in the mass of methanol added;methanol addition to diesel fuel was found to have a strong influence on the NOx concentration at high engine loads rather than at low engine loads, and a flat NOx-smoke trade-off curve exists when operating with the diesel-methanol fuel blends.

关键词： Ignition systems

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Liquid mean velocity and turbulence in a horizontal air-water bubbly flow

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Nuclear Science and Techniques 2003年第2期14卷 149-152页

作者： YANG Jian, ZHANG Ming-Yuan, ZHANG Chao-Jie, SU Yu-Liang (The state key lab.of multiphase flow in power engineering, Xi ’an Jiaotong University, Xi ’an 710049) Xi'an Jiaotong University The State Key Lab of Multiphase Flow in Power Engineering Xi'an 710049

The liquid phase turbulent structure of an air-water bubbly horizontal flow in a circular pipe has been investigated experimentally. Three-dimensional measurements were implemented with two "X" type probes oriented in different planes, and local liquid-phase velocities and turbulent stresses were simultaneously obtained. Systematic measurements were conducted covering a range of local void fraction from 0 to 11.7%. The important experiment results and parametric trends are summarized and discussed.

关键词：湍流气泡流液体速度热膜风速测定法

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