应用超临界流体技术制备纳米材料的研究进展

超临界流体以其粘度低、密度大、较好的传质、传热和溶解性等特性，在许多领域都有广阔的应用前景。纳米微粒材料在磁性材料、电子材料、光学材料等方面极具应用价值．故其制备技术已成为化学工程研究的一个新兴领域。本文主要介绍超临界流体技术在纳米材料制备中的应用与发展。     

超临界流体制备纳米催化剂的方法

超临界流体以其粘度低、密度大、较好的传质、传热和溶解性等特性,故在许多领域都有广阔的应用前景。纳米催化剂相对常规尺寸的催化剂具有更高的表面原子比,更大的此表面积,表面能等优点,故其制备技术已成为化学工程研究的一个新兴领域。本文主要介绍3种新兴的超临界流体化学合成纳米催化剂的方法：超临界水热合成法、超临界水解和超临界渗透吸附法。     

采用增大凝结液滴方法的锥芯超音速旋流分离装置性能研究

To improve the separation performance of a supersonic gas separation device for the treatment of gas mixture with a single heavy component, a novel structure with shorter settlement distance was constructed and a method of droplet enlargement was applied. A series of experiments were carried out in the improved separation device under various conditions, using air-ethanol vapor as the medium and micro water droplets as nucleation centers. The effects of the inlet pressure, temperature and relative humidity, the swirling intensity, and mass flow rate of water on the separation performance were investigated. The separation was improved by increasing the inlet pressure and relative humidity. With the decrease of swirling intensity and mass flow rate of water, the separation efficiency increased first and then decreased. The inlet temperature had a slight effect on the separation. The results showed that the separation performance was effectively improved using the proposed structure and method, and the best separation in this study was obtained with the ethanol removal rate about 55% and dew point depression 27 K. The addition of water had little pollution to the air-ethanol vapor system since the water carry-over rate was within the range of %-0 in most cases.     

一种空温式低温星形自增压汽化器的轻量化设计

文章针对一种低温液体储罐自带的汽化器,根据所满足的热量平衡、几何尺寸要求以及每根星形翅片管上平直翅片数目要求等约束条件和,以汽化器总质量最小为目标函数,建立了一个以汽化器几何尺寸参数和翅片数目为优化变量的混合整数非线性规划模型(MINLP问题)。利用分支界定法求解该优化模型,可以得到不同工况下汽化器的最优几何结构。计算表明,在设计工况下,优化后的汽化器质量相对初始设计以往减轻25.3%,这表明优化设计能有效减少汽化器质量。本文也讨论了环境温度对气化器几何尺寸和总质量的影响,在汽化要求一定时,随着环境温度的增加,所需汽化器的总设计长度和总质量以及翅片管的数量都逐渐减小,并与环境温度之间呈非线性关系。