无沸腾喷雾冷却技术的研究进展

文中简述了无沸腾喷雾冷却技术近年来国内外的研究进展。着重介绍了关于影响无沸腾区换热各参数的实验研究,如壁面温度、介质体积通量、喷雾流量、喷雾倾角和喷雾高度等,为寻求最佳换热提供了指导。并对无沸腾区的理论研究内容进行了归纳,主要是模拟不同喷雾条件下的换热过程及特性参数(如液膜厚度)的大小和分布,并将理论值与实验数据进行比较分析;总结了影响无沸腾区换热的喷雾特性参数和外部特性。     

Tuning circular Bragg phenomenon of TiO2 sculptured thin films with chiral structure

TiO2 chiral sculptured thin films （CSTFs） prepared using glancing angle deposition （GLAD） method based on electron beam evaporation are studied. The relationship between structural parameters and circular Bragg phenomenon （CBP） is investigated. Results demonstrate that, the central wavelength of Bragg regime red-shifts with the increasing pitch of helix, and peak value of selective transmittance will increase after adding more turns to the helix. After annealing, the central wavelength blue-shifts and the peak value rises. Tuning CBP by modulating the deposition parameters and annealing can optimize the performance of circularly polarized devices fabricated from CSTFs.     

固体表面上流动膜沸腾与液滴蒸发机理研究的新进展

当单个液滴落在温度超过某一临界值的炽热固体表面上时,液滴会像弹性球一样跳跃,并伴随着液滴表面蒸发而滴径逐步缩小.这种现象由J.G.Leidenfrost在1756年所发现,是物理学上著名的“球化态”奇异现象,称为Leidenfrost现象.出现此现象的热表面临界温度则称为 Leidenfrost温度(LFT).不同液体在不同压力下和不同表面状况的LPT是不同的.常压下水在一般平整度的钢铁表面上的LFT大约为300℃.液滴大小不同时所呈现的Leidenfrost现象也会有差异.滴径较大的液滴撞击温度超过LFT的热表面时,将克服表面张力的制约而伸展成圆盘状,悬浮在炽热固体…     

煤燃烧过程中汞、砷、硒反应机理研究

本文以三种典型煤为对象,测定了煤及灰中汞,砷,硒的浓度,了解了元素的挥发性。对钱家营褐煤进行了不同温度的燃烧实验。测定了在不同温度下燃烧灰中汞,砷,硒的含量变化。将所得实验结果与化学热力平衡分析工具F~*A~*C~*T2.1模拟系统结果相比较。推测了其中可能发生的反应。     

EFFECT OF NOZZLE FAN ANGLE ON SPRAYS IN GAS-SOLID RISER FLOW

A three-dimensional simulation study is performed for investigating the hydrodynamic behaviors of a cross-flow liquid nitrogen spray injected into an air-fluidized catalytic cracking （FCC） riser of rectangular cross-section. Rectangular nozzles with a fixed aspect ratio but different fan angles are used for the spray feeding. While our numerical simulation reveals a generic three-phase flow structure with strong three-phase interactions under rapid vaporization of sprays, this paper tends to focus on the study of the effect of nozzle fan angle on the spray coverage as well as vapor flux distribution by spray vaporization inside the riser flow. The gas-solid （air-FCC） flow is simulated using the multi-fluid method while the evaporating sprays （liquid nitrogen） are calculated using the Lagrangian trajectory method, with a strong two-way coupling between the Eulerian gas-solid flow and the Lagrangian trajectories of spray. Our simulation shows that the spray coverage is basically dominated by the spray fan angle. The spray fan angle has a very minor effect on spray penetration. The spray vaporization flux per unit area of spray coverage is highly non-linearly distributed along the spray penetration. The convection of gas-solid flow in a riser leads to a significant downward deviation of vapor generated by droplet vaporization, causing a strong recirculating wake region in the immediate downstream area of the spray.     

简化刚体状态方程及其应用——Ⅰ.参数确定

提出了一个简化的二参数刚体状态方程,可用作立方型方程的斥力项。从参数的物理意义出发,结合一些合理的假定,探讨了确定两个参数的方法。由正构烷烃的饱和液体体积和△H_b值,得到了上述两个参数的关联式。并推算了烯烃、支链烷烃和某些非烃类物质的△H_b,结果和文献值符合良好。     

氟化电热蒸发（ETV）—ICP—AES直接测定生物试样中不同挥发性元素…

本文以聚四氟乙烯（ＰＴＥＥ）悬浮体为氟化剂，对悬浮体制样ＥＴＶ－ＩＣＰ－ＡＥＳ直接测定生物试样中不同挥发性元素钼、铜和镉的蒸发行为，影响因素及分析性能进行了比较研究，得出了相应的规律性。在选定实验条件下，本法测定Ｍｏ，Ｃｕ和Ｃｄ的检出限分别为０．４３、４．２和１４１ｎｇ／ｍＬ，ＲＳＤ分别为３．８％、４．２％和２．２％。提出的方法已应用于ＣＲＭ２８１生物标样分析，结果与参考值吻合。     

STRUCTURAL DAMAGE MODEL OF UNSATURATED EXPANSIVE SOIL AND ITS APPLICATION IN MULTI-FIELD COUPLE ANALYSIS ON EXPANSIVE SOIL SLOPE

Focused on the sensitivity to climate change and the special mechanical characteristics of undisturbed expansive soil, an elastc-plastic damage constitutive model was proposed based on the mechanics of unsaturated soil and the mechanics of damage. Undisturbed expansive soil was considered as a compound of non-damaged part and damaged part. The behavior of the non-damaged part was described using non-linear constitutive model of unsaturated soil. The property of the damaged part was described using a damage evolution equation and two yield surfaces, i.e., loading yield (LY) and shear yield (SY). Furthermore, a consolidation model for unsaturated undisturbed expansive soil was established and a FEM program named UESEPDC was designed. Numerical analysis on solid-liquid-gas tri-phases and multi-field couple problem was conducted for four stages and fields of stress, displacement, pore water pressure, pore air pressure, water content, suction, and the damage region as well as plastic region in an expansive soil slope were obtained.