高温液相添加剂对纳米LiBr溶液表面张力和沸腾温度的影响

通过在纳米溴化锂(LiBr)溶液中添加表面活性剂降低溶液沸腾温度,从而有助于大幅度应用工业余热、废热等低品味热源。尽管影响沸腾温度的因素较多,但是溶液的表面张力是一个重要的因素,首先对异辛醇(C8H18O)、壬醇(C9H20O)和癸醇(C10H22O)3种高沸点液相添加剂对纳米LiBr溶液的表面张力的影响做了深入研究,并进一步研究了相对应的沸腾温度。并且通过实验发现随着烷醇中烷基数增加,表面张力更低,使得沸腾温度也进一步降低。     

纳米溴化锂溶液稳定性及其沸腾温度研究

对既有溴化锂溶液、纳米微粒及其相应分散剂配制的纳米溶液,对比测试其与纯溴化锂溶液的表面张力和沸腾温度,探讨了该纳米溶液的热物性及稳定性。实验发现,添加纳米微粒溶液的表面张力明显降低,经过温度工艺处理后,发现溶液中纳米微粒的颗粒度降低,纳米微粒在溴化锂溶液中几乎完全溶解,纳米溶液显现出很好的稳定性,其表面张力和沸腾温度均比纯溴化锂溶液有所降低。研究表明,最佳组份配制的纳米溶液与纳米微粒和相关分散剂有关,经过严格温度处理工艺流程,可获得稳定性、热物性良好的纳米溴化锂溶液,有利于在工程中应用。     

分散剂对纳米LiBr溶液稳定性的影响

文章在论述分散剂增强纳米流体分散稳定性的基础上,通过添加E414和C6H5O7（NH4）,验证分散剂增强纳米LiBr溶液的分散稳定性,通过测量分别添加异辛醇（C8H18O）、壬醇（C9H20O）和癸醇（C10H220）基液的表面张力,发现分散剂也能增强纳米LiBr溶液表面张力的稳定性,主要因为表面张力和汽化成核临界功之间存在相关性,因此,分散剂同样能增强纳米LiBr溶液沸腾温度的稳定性。     

添加纳米粒子的溴化锂溶液传质特性

建立了纳米溴化锂溶液二维降膜传热传质数学模型,以实验数据对模型进行验证。研究结果表明,在溴化锂溶液中加入纳米粒子可以显著增强溴化锂溶液对水蒸气的吸收速率,并且随着纳米粒子添加量的增大,纳米溴化锂溶液对水蒸气的吸收速率越大;在纳米粒子添加量相同时,纳米溴化锂溶液的水蒸气吸收速率随着溶液流量的增大而增大,且水蒸气吸收速率随溶液流量的变化趋势为对数曲线趋势;溶液的传质强化比随着纳米粒子添加量的增加而增大;在溴化锂溶液中加入纳米粒子后,吸收器的传质系数随着纳米粒子添加量的增大而增大,在溶液流量为1.2 L/min时,添加0.05%纳米粒子后,吸收器传质系数增加1.32倍,添加0.1%纳米粒子后,吸收器传质系数增加1.41倍,但是,传质系数增幅随着纳米粒子含量的增加而逐渐减弱。     

溴化锂制冷机溶液的维护和再生

溴化锂制冷机组要使制冷效果始终处于最佳状态，机组使用寿命延长，除保证机组处于良好的气密性外，对机用溴化锂溶液进行日常维护、定期检测和调整是必不可少的。     

添加剂对硝酸铵饱和溶液表面张力的影响

添加剂对硝酸铵(AN)防潮、防结块的作用与其饱和溶液的性质有着密切的关系。文中选用了一些表面活性剂和高分子化合物对添加剂单一组分和复合组分在AN饱和溶液中的表面张力进行了实验,结果证明含有添加剂的AN饱和溶液表面张力与添加剂的作用具有良好的一致性。     

含有促进传热传质添加剂的溴化锂水溶液的表面张力

采用Wilhelmy平板法,对未加入添加剂和加入添加剂(4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-hexanol, 2,4-dimethyl-3-pentanol, 4-heptanol, 2-heptanol, 1-heptanol, 2EH)的溴化锂水溶液的表面张力进行了测量.通过与相关添加剂对溴化锂溶液吸收水蒸气速度影响的测试实验结果进行关联分析,结果表明,对于酒精类添加剂,在含碳原子数相同的情况下,使溶液表面张力降低越大的添加剂使溶液吸收水蒸气的速度越快.     

常压下溴化锂水溶液沸腾换热特性实验研究

除湿剂的沸腾式再生区别于喷淋式再生,受室外环境影响小,具有广阔的应用前景。溶液的沸腾特性的研究对沸腾再生器的设计有重要意义。针对常规除湿溶液LiBr水溶液的池内核态沸腾特性展开实验研究,研究发现：实验范围内,LiBr溶液的沸腾换热系数远低于纯水,并随浓度的增加而降低;溶液稳定沸腾再生对热源温度的要求并不高,LiBr溶液的沸腾温度,随着浓度的增加而升高;溶液沸腾换热机理较单一组分液体沸腾更为复杂,有待进一步深入研究。     

添加剂和纳米粒子强化溴化锂水溶液／氨水吸收特性研究进展

吸收式制冷以其节能、环保等诸多优点得到了越来越广泛的应用。本文总结与分析添加剂和纳米粒子强化溴化锂水溶液及氨水吸收特性的机制和相关实验研究的发展现状。针对吸收式制冷系统中吸收器传质系数和换热系数小而导致的制冷效率低的问题,很多学者进行了添加剂和纳米粒子对吸收过程影响的实验研究,并据此采取措施增大传质传热效率。实验主要包括以下几个方面：表面张力实验、静态池吸收实验、降膜吸收实验和氨水鼓泡吸收实验。实验结果均表明添加剂和纳米粒子可以提高吸收器中溴化锂水溶液及氨水的传热传质性能。该研究对于提高吸收式制冷系统的制冷效率有很大帮助,同时为该技术在实际系统中的应用奠定基础。     

Surface Tension of Liquid Alumina from Contactless Techniques

New data for the surface tension of liquid alumina from 2300 to 3200 K are reported. Aerodynamic levitation of CO₂ laser-heated liquid drops allowed contactless measurement of vibration frequencies directly related to surface tension. Consistent data were obtained on drops of different mass ranging from 20 to 160 mg. It was also shown that the oxydo-reducing character of the atmosphere does not modify the results within experimental uncertainty.     

Surface Tension and Density of Oxygen-Free Liquid Aluminum at High Temperature

New values of densities and surface tensions of liquid aluminum obtained in the range 1600 to 2360 K by contactless techniques in neutral gases are reported. Conditions for oxygen-free aluminum are fulfilled which allow determination of the surface tension of aluminum. Extrapolation to the melting point, T _m = 933 K, confirms the value of (T = 933K) = 1.05 N m^–1.     

The Law of Corresponding States and Surface Tension of Liquid Metals

Empirical relationships for the surface tension of liquid metals (LM) are shown to follow from the principle of corresponding states. In order to relate the surface tension of LM to its bulk properties, a formula is derived by scaling with the melting point T _m (0) at the atmospheric pressure, p = 0 and the atomic volume _m (0) at the melting point as macroscopic parameters for scaling and a characterizing the interatomic potential (r)= *(r/a). Correlation rules, derived for the surface tension and its temperature coefficient, are discussed and compared with experimental data.     

Equation of State for Complex Liquid Mixtures from Surface Tension

The present work shows a successful extension of previous studies to molecular liquids for which the second virial coefficients are not known. Recent advances in the statistical mechanical theory of equilibrium fluids can be used to obtain an equation of state (EOS) for compressed normal liquids and molten alkali metals. Three temperature-dependent quantities are needed to use the EOS: the second virial coefficient, B(T), an effective van der Waals covolume, b(T), and a scaling factor, (T). The second virial coefficients are calculated from a correlation that uses the surface tension, _tr, and the liquid density at the triple point. Calculation of (T) and b(T) follows by scaling. Thus, thermodynamic consistency is achieved by use of two scaling parameters (_tr, _tr). The correlations embrace the temperature range T _tr<T<T _c and can be used in a predictive mode. The remaining constant parameter is best found empirically from _tr data for pure dense liquids. The equation of state is tested on 42 liquid mixtures The results indicate that the liquid density at any pressure and temperature can be predicted within about 5%, over the range from T _tr to T _c.     

Measurement of the Surface Tension of Undercooled Liquid Ti90Al6V4 by the Oscillating Drop Technique

The surface tension of liquid Ti₉₀Al₆V₄ was measured. The samples have been processed containerlessly by electromagnetic levitation, which allows the handling of highly reactive materials and measurements in the undercooled temperature region. The use of digital image processing allows the identification of oscillation modes and calculation of the surface tension from the l = 2 and m = 0, m = 2 oscillation modes. A linear least squares fit to the data showed the following temperature dependence: = 1.389 ± 0.09 – 9.017 × 10^–4 ± 5.64 × 10^–5(T – 1660°C) [Nm^–1]     

一种测定液体表面张力系数的新方法

针对现有的测定液体表面张力系数的方法存在设备昂贵、测定结果容易受各种因素干扰而测试精度不足等问题,提出了一种使用不等内径U型管,采用局部力平衡方法结合拉普拉斯方程,以及MATLAB图像处理和LabVIEW虚拟仪器系统,测定液体表面张力系数的方法。与现有的测定液体表面张力系数的拉脱法相比,该方法具有测试精度高、样品需要量少、测试成本低等特点。     

表面张力匹配对多层坡流涂布质量的影响

从实测大生产物料的动态表面张力和静态表面张力数据，用表面活性剂在涂布液的扩散和在新表面吸附过程，分析涂布过程出现的余布弊病，并提出解决的办法。     

Density and Surface Tension of Liquid Ternary Ni–Cu–Fe Alloys

The density and surface tension of liquid Ni–Cu–Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator equipped with facilities for optical densitometry and oscillating drop tensiometry. At temperatures above and below the liquidus point, the density and surface tension are linear functions of temperature. The concentration dependence of the density is significantly influenced by a third-order (ternary) parameter in the excess volume. The surface tensions are rather insensitive to substitution of the two transition metals Ni, Fe against each other and depend only on the copper concentration. By numerically solving the Butler equation, the surface tension of the ternary system can be derived from the thermodynamic potentials ^E G of the binary phases (Ni–Cu, Fe–Cu, Ni–Fe) alone.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.