煤的模型化合物混合燃料气流床气化中N的迁移研究

将吡啶配入柴油中模拟煤中氮的存在形式,考察了混合燃料在四喷嘴对置式气化炉中,轴径向位置HCN、NH3、NO和N2的浓度分布。结果表明：氮污染物(HCN、NH3、NO)在喷嘴平面处即产生且浓度最高,远离喷嘴平面时其浓度大幅降低,N2也裂解参与了气化反应,且出口浓度N2>HCN>NH3>NO;氧燃料比增高,NO、N2增加;氧燃料比1.3时HCN、NH3浓度最高,0.9和1.7时浓度较低;流场的分布使靠近出口处径向浓度基本一致,而上部各平面位置浓度靠近炉壁处最低;水汽的加入使HCN、NH3浓度增高而NO浓度降低。     

灰熔聚流化床气化炉的CFD模拟研究

通过CFD模拟了灰熔聚流化床气化炉,考察了操作条件包括中心管氧气量、分布板水蒸气量以及操作压力对流化床气化炉的气相浓度分布的影响。剖析了不同操作条件对化学反应的影响,解释了其对气化炉产气组成的作用原理。     

Pulsed neutron powder diffraction at high pressure by a capacity-increased sapphire anvil cell

A new design of opposed anvil cell for time-of-flight neutron powder diffraction was prepared for use at advanced pulsed sources. A couple of single-crystal sapphire sphere anvils and a gasket of fully hardened Ti–Zr null alloy were combined to compress 35 mm³ of sample volume to 1 GPa and 11 mm³ to 2 GPa of pressures, respectively. A very high-quality powder diffraction pattern was obtained at Japan Proton Accelerator Research Complex for a controversial high pressure phase of methane hydrate. The counting statistics, resolution, absolute accuracy and d-value range of the pattern were all improved to be best suitable for precise structure refinement. The sample is optically accessible to be measured by Raman and fluorescence spectroscopy during and after compression. The current cell will be an alternative choice to study hydrogenous materials of complex structures that are stable at the described pressure regime.     

Extensional rheology of concentrated poly(ethylene oxide) solutions

The shear and extensional rheology of three concentrated poly(ethylene oxide) solutions is examined. Shear theology including steady shear viscosity, normal stress difference and linear viscoelastic material functions all collapse onto master curves independent of concentration and temperature. Extensional flow experiments are performed in fiber spinning and opposed nozzles geometries. The concentration dependence of extensional behavior measured using both techniques is presented. The zero-shear viscosity and apparent extensional viscosities measured with both extensional rheometers exhibit a power law dependence with polymer concentration. Strain hardening in the fiber spinning device is found to be of similar magnitude for all test fluids, irrespective of strain rate. The opposed nozzle device measures an apparent extensional viscosity which is one order of magnitude smaller than the value determined with the fiber spinline device. This could be attributed to errors caused by shear, dynamic pressure, and the relatively small strains developed in the opposed nozzle device. This instrument cannot measure local kinematics or stresses, but averages these values over the non-homogenous flow field. These results show that it is not possible to measure the extensional viscosity of non-Newtonian and shear thinning fluids with this device. Fiber spin-line experiments are coupled with a momentum balance and constitutive model to predict stress growth and diameter profiles. A one-mode Giesekus model accurately captures the plateau values of steady and dynamic shear properties, but fails to capture the gradual shear thinning of viscosity. Giesekus model parameters determined from shear rheology are not capable of quantitatively predicting fiber spinline kinematics. However, model parameters fit to a single spinline experiment accurately predict stress growth behavior for different applied spinline tensions.     

High pressure resistivity studies on La1+xBa2-xCu3Oy system

Abstract

We report here an electrical resistivity study on La_1+xCu₃O_y system under high pressure up to 80 kbar. The three different oxides, %ained from the main system by varying the values of x, are prepared by solid state reactions. Bridgman opposed anvil device is used. The normalised resistivity as a function of pressure for the oxides yields interesting results.     

平面撞击流偏斜振荡的实验研究与大涡模拟

采用实验和大涡模拟对喷嘴出口雷诺数(Re= U₀ hρ/μ, 其中 U₀为出口平均速度, h为平面喷嘴出口狭缝高度, ρ和 μ分别为流体的密度与动力黏度)为25–10000, 喷嘴间距 L为4h–40h范围内的平面撞击流偏斜振荡特性进行了研究. 通过对平面撞击流模拟和实验的结果进行比较, 验证了数值模拟的可靠性, 并对平面撞击流发生偏斜振荡的无因次参数(喷嘴间距 L/h与出口雷诺数 Re)范围进行划分, 重点考察了湍流平面撞击流的偏斜振荡周期及速度-压力变化特征. 研究结果表明大涡模拟能对平面撞击流的偏斜振荡进行有效预报; 当平面撞击流发生周期性偏斜振荡时, 特定点的压力与速度也发生周期性变化, 且变化周期与偏斜振荡周期一致, 偏斜振荡本质上是由速度-压力的周期性变化和转换引起的. 关键词： 平面撞击流 偏斜振荡 大涡模拟     

Time-resolved conditional flow field statistics in extinguishing turbulent opposed jet flames using simultaneous highspeed PIV/OH-PLIF

Time-resolved particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF), both at 5 kHz, were applied simultaneously on extinguishing turbulent opposed jet flames. This repetition rate allowed tracking of transient extinction events in turbulent combustion. The additional information acquired about time history enabled a study of the evolution of vortex-flame interactions leading to extinction from individual events. A newly introduced multidimensional conditioning technique to avoid spatial- and temporal-smearing of important flow field information was developed in order to compare individual extinction events in a meaningful, statistical manner. The conditional statistics show that vortices tend to align around the flame and generate regions of high strain in the region where the flame is about to extinguish.     

Electrochemical Behavior of Parallel Opposed Dual Electrode in a Microchannel

The electrochemical behavior dependent on the microchannel depth is discussed using a parallel opposed dual electrode in the microchip. The microchannel depth was controlled easily by the thickness of the photoresist. Cyclic voltammetry (CV) was carried out with conventional mode and the generation‐collection mode. High collection efficiency (max: 98%) and high current amplification (max: 5.2) were achieved without miniaturizing the dual electrode by micromachining techniques, when the microchip with the microchannel depth of 30 μm was used in the generation‐collection mode at low sweep rates. Quantitative analysis was applied to electrochemically reversible species with a quicker response time of around a few seconds for the same microchannel depth on chronoamperometry (CA). We observed good linearity on the calibration plot of dopamine (2×10^?6 – ca. 1×10^?3 mol dm^?3 ).     

四喷嘴对置式气化炉停留时间分布的随机模型

运用连续时间马尔可夫链及矩阵相关理论,建立了停留时间分布随机模型。根据对四喷嘴对置式气化炉流场的测试,将气化炉划分为若干区域,并且对各个区域体积进行了估算,组成马尔可夫链状态转移图。模拟计算表明,当射流回流区和撞击流回流区回流比为1,管流区为平推流模式,其他区域按全混流模式处理时,模拟值与实验值较接近。用优化的模型计算了不同条件的冷模气化炉的停留时间分布,结果表明,随着气体流量的增大,平均停留时间减小,无因次方差增大;随着炉体高度的增加,平均停留时间增大,无因次方差减小。对工业气化炉停留时间分布进行了预测,炉内流型总体上趋近于全混流,有利于炉内的气化反应。     

射流流化床煤气化炉中气固流动和传热、传质的CFD模拟研究

通过双流体模型对射流流化床煤气化炉进行了CFD（Computational Fluid Dynamics,计算流体力学）模拟。模拟着重分析了流化床气化炉气固流动的特性和传质、传热过程。结果表明,流化床中气固两相的传热、传质过程与气体和颗粒的运动特性密切相关。