液相扩散系数测定方法的近期研究进展

由于液相扩散系数的理论预测和各种估算方法还不够成熟和完善，因此其实验测定的方法尤其受到人们的关注和重视。本文对一些常用的液相扩散系数的测定方法进行了介绍；并着重介绍了一种新型的现代光学测量方法－－激光全息干涉法。     

全息激光干涉技术测定气体的液相扩散系数

介绍了一种测定液相扩散系数的实时激光全息干涉系统。通过该系统得到清晰表征浓度场分布的实时全息干涉条纹图,利用全息干涉原理及相应的数学关系处理干涉条纹,得到液相扩散系数。利用该方法测定了CO2在乙醇、正丙醇中的扩散系数,结果与文献值非常接近。该方法具有实时、快速、简单和准确等优点,它是一种发展前景很好的液相扩散系数测定方法。     

激光全息干涉法测量液相质扩散系数数字图像处理的研究

用He-Ne激光器、CCD和图像采集系统等仪器设备,搭建了数字激光全息干涉法测量液相质扩散系数的实验系统,并测试获得了浓度为0.33 mol/l KCl水溶液在298.15 K温度下的全息干涉图像,采用了图像增强、全息干涉条纹图再现及相位展开等数字图像处理过程的关键技术对全息干涉图进行处理,得到了相位展开后物光相位差,经换算后获得了该溶液的质扩散系数.为化工工程上研究替代制冷荆急需的质扩散系数测量提供了有效的方法.     

基于干涉条纹极值点质扩散系数的数学描述

以费克第二定律为理论基础,依据半无限厚板中扩散过程的原理建立质扩散数学模型,并在模型中采用激光全息干涉实验方法测得干涉条纹极值参数,进而获得液液质扩散系数数学描述。测得温度为15℃时,浓度0．10mol／L的蔗糖溶液向水溶液中扩散产生的干涉条纹极值,计算出蔗糖溶液液相质扩散系数值,与文献值比较,其误差为3．67％,标准偏差为0．378,验证了基于干涉条纹极值点质扩散公式的准确性。为化工工程上研究替代制冷剂急需的质扩散系数的理论研究提供了有效的数学方法。     

碳酸二乙酯在正庚烷和空气中质扩散系数测量

利用自行搭建的数字激光全息干涉法测量流体液液、气液质扩散系数的实验装置,在标准大气压下,温度在278.15—338.15 K内,测量了含氧替代燃料碳酸二乙酯分别在正庚烷和空气中21个温度点的质扩散系数;同时,使用Wilke-chang方程、Scheibel方程和Reddy-Doraiswamy方程对碳酸二乙酯在正庚烷中的质扩散系数进行了估算,并与实验数据进行了比较分析。为替代燃料碳酸二乙酯的科研开发提供了热物性基础数据。     

数字全息干涉法测量液相质扩散系数的研究

介绍数字全息干涉法测量原理.设计并搭建基于数字全息干涉法和新的扩散槽测量质扩散系数的实验系统,并使用此系统测量了浓度为0.33 mol/l的KCl水溶液在温度为291.8、294.7、298.8、299.8、305.4、308.5、315.2 K条件下的质扩散系数,实验结果表明实验值和文献参考值之间相对偏差绝对值的平均数为1.3%,验证了试验系统的精确性和可靠性.最后,在此系统上测量了浓度为0.1 mol/1的蔗糖水溶液在288.15～338.15 K温度范围内的质扩散系数.为测量工程上急需新型燃料替代工质和新型制冷剂替代工质的质扩散系数提供了一种新的有效方法.     

数字全息干涉法测量二元溶液互扩散系数

由一维无限长扩散模型入手,建立了探测光相位与液体互扩散系数之间的数学模型,进而在现有数字全息干涉法的基础上,提出了一种新型的二元液体互扩散系数测量方法。由于该方法直接利用探测光相位求取互扩散系数,因此可有效避免外界噪声信号对实验结果的影响,从而降低了数字全息干涉法对外界光学环境的要求。该方法的互扩散系数测量相对合成不确定度为0.7%。测量了25℃下、0.33 mol/L KCl水溶液的互扩散系数,实验结果与文献值符合良好,验证了该测量方法的可行性。利用该方法,测量了甲醇/环己烷二元系在其不互溶区附近的互扩散系数,揭示了其在该区域的变化规律。依据实验数据,预测了该二元系的热力学亚稳定和非稳定区域的分界线——Spinodal曲线。     

数字全息干涉法测量二元溶液互扩散系数

由一维无限长扩散模型入手,建立了探测光相位与液体互扩散系数之间的数学模型,进而在现有数字全息干涉法的基础上,提出了一种新型的二元液体互扩散系数测量方法。由于该方法直接利用探测光相位求取互扩散系数,因此可有效避免外界噪声信号对实验结果的影响,从而降低了数字全息干涉法对外界光学环境的要求。该方法的互扩散系数测量相对合成不确定度为0.7%。测量了25℃下、0.33 mol/L KCl水溶液的互扩散系数,实验结果与文献值符合良好,验证了该测量方法的可行性。利用该方法,测量了甲醇/环己烷二元系在其不互溶区附近的互扩散系数,揭示了其在该区域的变化规律。依据实验数据,预测了该二元系的热力学亚稳定和非稳定区域的分界线--Spinodal曲线。     

数字全息法测量液相扩散系数实验研究

采用数字全息干涉法测量了25℃乙二醇-水物系的扩散系数。详细介绍了实验方法以及2种处理干涉图像获得扩散系数的方法,即横条纹法和弯条纹法。通过测量25℃时0.33 mol/L KCl溶液的扩散验证了实验的精确性。分别用2种方法获得了6个不同质量分数下的乙二醇-水物系的扩散系数,并与文献值进行了对比。结果表明,弯曲条纹法的平均相对偏差是1.3%,比水平条纹法的1.7%小,同时,弯曲条纹法的平均标准偏差更小,说明波动更小。     

液相扩散——理论、预估及实测

本文内容以非电解质的二元液相扩散为主,分为四个部分:1.液相扩散的现象表达;2.液相扩散理论,包括流体动力扩散理论。绝对速度理论及其它理论;3.液相扩散系数的预估关联式,包括无限稀释时的关联、与浓度的关联和与温度的关联;4.液相扩散系数的测定方法,包括膜池法、光干涉法、放射性同位素法、核磁共振法和分散法等。     

Anwendung der holographischen Interferometrie zur zerstörungsfreien Material- und Bauteileprüfung

Use of holographic interferometry for nondestructive testing of materials and components . Holographic interferometry represents a useful tool for measurement of deformations over large surface areas of any constructional or plant components. Application of the stresses encountered in operation reveal weak spots endangering the component owing to improper production methods or to material defects. Furthermore, particularly small material defects can be detected on generation of waves by an impact loading; interference at cracks is clearly displayed in the holographically stored interference picture.     

Mass diffusion coefficients of polymer films using real-time holographic interferometry

The mass diffusion coefficient is obtained using real-time holographic interferometry. The stresses induced during desorption and absorption of moisture are monitored as a function of time at various relative humidities. A mathematical relationship is applied to relate these stresses to the moisture diffusion through the thickness of the films. The advantage of the holographic interferometry technique is that both the swelling stress as a function of time and the mass diffusion coefficient can be quantified simultaneously during the same experiment. Several films and coatings were investigated: polyimides (PMDA–ODA and BPDA–PAA), photographic gelatin, and cellulose acetate. Each exhibited characteristic Fickian diffusion behavior. A gravimetric technique was employed to validate the holographic interferometry results. The moisture diffusion coefficients determined by holographic interferometry agreed well with reported literature values. © 1996 John Wiley & Sons, Inc.     

Optical errors encountered in using holographic interferometry to observe liquid boundary layers in electrochemical cells

A method of numerical integration is presented which makes it possible to predict the form of interference fringes observed when holographic interferometry is used to study boundary layers. Results of calculations for diffusional boundary layers formed under conditions of fully developed laminar flow are discussed. It is shown that use of holographic interferometry in the place of more traditional methods eliminates one type of error induced by light-deflection effects.     

Monitoring and measuring electrochemical behavior of engineering alloys by optical interferometry

In a previous study, an optical corrosion meter was built based on a mathematical model relating to surface and bulk behaviors of metals in aqueous solution. The optical corrosion meter was established based on principles of holographic interferometry for measuring microsurface dissolution, i.e., mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e., corrosion current. The corrosion meter consists of an electrochemical cell in which the sample is immersed in aqueous solution. Furthermore, the corrosion meter has a holographic camera with a thermoplastic film for in situ processing holograms in order to obtain real-time holographic interferograms of the sample in the electrochemical cell. Results of the present work indicate that optical holography is a very useful technique for measuring the corrosion current density of different alloys in aqueous solutions. As a result, the corrosion current density of aluminium, stainless steel, low carbon steel, copper, and brass in 1M KCl, 1 M NaCl, 1 M NaOH, seawater and seawater solutions, respectively, were obtained. The obtained corrosion data from the optical corrosion meter (interferometric technique) were compared with corrosion data obtained on the same alloys in the specified solutions from the linear polarization method as well as from the weight-loss method. The comparison among the three techniques indicates that there is contrast in the results among the investigated alloys. In general, the new method of optical interferometry can be considered a more conservative method of corrosion measurement with respect to the linear polarization and weight-loss methods.     

聚合物体系中小分子物质扩散系数的测定

简述了用本体平衡法，逆流气相色谱法，自旋回声脉冲梯度场的核磁共振法和激光全息干涉技术测定聚合物体系中小分子物质的扩散系数。     

Optimization of the method for color measurement of printing on holographic paper

Color is one of the most important quality control parameters for printing, but there is no applicable color measurement method for printing on holographic paper. The aim of this study was to analyze the reason why current instruments are unable to provide accurate color measurement for holographic paper printing and find a way to solve the problem. Diffuse geometry instrument was proved to be more suitable than directional geometry instrument for holographic paper printing. Variations in the measured color coordinates due to holograph patterns were observed by measuring four types of holographic papers before and after printing. The distribution uniformity and the area of holographic patterns were considered as the main factors that influence measurement repeatability and consistency. By using d:8° geometry instrument in specular component included (SCI) mode and large circular measured area, measurements at two angles of the same point and averaging, or measurements at three different positions and averaging were proved to improve the measurement repeatability on a single point and measurement consistency on a single sheet of holographic paper. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2013