Subcritical and supercritical droplet evaporation within a zero-gravity environment: Low Weber number relative motion

A validated comprehensive axisymmetric numerical model, which includes the high pressure transient effects, variable thermo-physical properties and inert species solubility in the liquid phase, has been employed to study the evaporation of moving n-heptane droplets within a zero-gravity nitrogen environment, for a wide range of ambient pressures and initial freestream velocities. At the high ambient temperature considered (1000 K), the evaporation constant increases with the ambient pressure. At low ambient pressure, the evaporation constant becomes almost a constant during the end of the lifetime. At high ambient pressures, the transient behavior is present throughout the droplet lifetime. The final penetration distance of a moving droplet decreases exponentially with increasing ambient pressure. The average evaporation constant increases with ambient pressure. The variation is almost linear for reduced ambient pressures smaller than approximately 2. For higher values, depending on the initial freestream velocity, the average evaporation constant either becomes a constant (at low initial freestream velocities) or it non-linearly increases (at high initial freestream velocities) with the ambient pressure. Droplet lifetime decreases with increasing ambient pressure and/or increasing initial freestream velocity.     

CuInxGa1−xSe2 thin films prepared by electron beam evaporation

CuIn_xGa_1−xSe₂ bulk compound of three different compositions x=0.75, 0.80 and 0.85 have been prepared using individual elements of copper, indium, gallium and selenium. Thin films of CuIn_xGa_1−xSe₂ have been deposited using the prepared bulk by electron beam evaporation method. The structural studies carried on the deposited films revealed that films annealed at 400 °C are crystalline in nature exhibiting chalcopyrite phase. The position of the (1 1 2) peak in the X-ray diffractogram corresponding to the chalcopyrite phase has been found to be dependent on the percentage of gallium in the films. The composition of the prepared bulk and thin films has been identified using energy dispersive X-ray analysis. The photoluminescence spectra of the CuIn_xGa_1−xSe₂ films exhibited sharp luminescence peaks corresponding to the band gap of the material.     

磷铵尾气减排与节能的过程分析与实验

分析了60万吨/年磷酸二铵（DAP）生产装置尾气形成“磷铵雨”的热力学机理,提出尾气部分冷凝- 磷酸降膜蒸发过程耦合技术,现场实验证明了该技术的可行性,现场实验获得的P₂O₅质量分数27.1%～41.7%范围内磷酸蒸发浓缩数据,该工艺使尾气湿含量减少至0.065 kg H₂O/kg air。研究了磷酸液膜雷诺数以及磷酸液膜过冷度对磷酸降膜蒸发过程的影响,揭示了在55℃以下低温浓缩湿法磷酸的可能性。这对磷酸浓缩技术很有参考价值。     

TiO_2薄膜成分和结构分析及其对折射率的影响

在硅衬底上利用电子束蒸发沉积了TiO_2薄膜,利用椭圆偏振仪测量了不同沉积温度下的TiO_2薄膜的折射率,发现其折射率随着沉积温度的升高而升高.利用X射线衍射(XRD)仪对这些薄膜的结构进行表征,发现折射率高的样品其结晶化程度也高.利用X射线光电子能谱(XPS)和傅立叶红外吸收谱(FT-IR)相结合的方法对薄膜的成分进行分析,发现内部存在低价态的钛氧化物,使薄膜的折射率明显低于固体块材料的折射率.     

Mathematical Simulation of Lithium Bromide Solution Laminar Falling Film Evaporation in Vertical Tube

For utilization of the residual heat of flue gas to drive the absorption chillers,a lithium-bromide falling film in vertical tube type generator is presented.A mathematical model was developed to simulate the heat and mass coupled problem of laminar falling film evaporation in vertical tube.In the model,the factor of mass transfer was taken into account in heat transfer performance calculation.The temperature and concentration fields were calculated.Some tests were conducted for the factors such as Re numbe...     

Thermal analysis on the cooling performance of a porous evaporative plate for building

In this paper, a wet porous cooling plate has been used for a building wall. Cooling can be achieved due to the evaporation in the porous layer. A mathematical model on the heat and mass transfer in the unsaturated porous media is developed to analyze the influences of ambient conditions and the porous layer thickness on the cooling performance of the porous evaporative plate. With a decrease in ambient relative humidity and an increase in ambient temperature, more cooling of the porous evaporative plate can be supplied for the inside of the room. The heat exchange between the inside surface of the porous plate and the air in the room should be intensified to achieve a higher cooling efficiency of the porous plate. The ambient wind speed and the thickness of the porous plate also have significant influence on the average temperature of the porous plate. All these results should be taken into account for the utilization of the porous evaporative cooling plate. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20284     

Synthesis, characterization and optical properties of star-like ZnO nanostructures

Star-like ZnO nanostructures were synthesized in bulk quantity by thermal evaporation method. The morphologies and structure of ZnO nanostructures were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results demonstrated that the as-synthesized products consisted of star-like ZnO nanostructure with hexagonal wurtzite phase. The legs of the star-like nanostructures were preferentially grown up along the [0001] direction. A vapor-solid (VS) growth mechanism was proposed to explain the formation of the star-like structures. Photoluminescence spectrum exhibited a narrow ultraviolet emission at around 380 nm and a broad green emission around 491 nm. Raman spectrum of the ZnO nanostructures was also discussed.     

料浆法磷铵装置蒸发浓缩系统的扩能改造

介绍料浆法磷铵装置浓缩系统扩能改造的几种方案并重点介绍称为“双效三体流程”的扩能方案 ,论述其优越性 ,并通过校核计算证明了其可行性     

垂直管降膜蒸发传热研究进展

对垂直管降膜蒸发传热的实验研究和理论研究现状进行了综述,指出了目前研究中存在的问题,并对未来的研究方向提出建议。     

优化蒸发工艺 降低蒸汽消耗

对近几年山东大成农药股份有限公司氯碱厂烧碱蒸发工艺中存在的问题和采取的相应措施,及取得的效果进行了总结,并对现系统中仍存在的一些不足进行了探讨。