微波化学

简述了微波介电加热的原理。讨论了微波介电加热观察到的效应,特别是运用微波炉进行得较为成功的化学反应。     

微波敏化剂

利用敏化剂可使微波加热非极性聚合物,主要用导电碳黑或半导电碳黑及氧化铁黑,待开发Ｆｒｅｇｕｏｎ敏化剂。     

微波介质陶瓷

微波介质陶瓷作为广泛应用于微波谐振器、滤波器、介质基板、移相器等现代移动通信设备的核心材料,大大促进了现代通信事业的飞速发展。本文综述了近几十年来微波介质陶瓷的研究现状,以及各类体系微波介质陶瓷发展的最新进展,同时对微波介质陶瓷的发展趋势进行了讨论。     

高性能陶瓷微波介质材料

微波介质陶瓷可使微波通信和其他微波设备小型化,是有良好发展前景的一种介电材料。目前已经研制出许多具有高介电常数、高品质因数、低介质损耗及小谐振频率温度系数的优质微波介质陶瓷。本文综述近年来微波介质陶瓷在制备工艺、改良介电性能及应用方面的最新进展,并指出了今后的研究方向。     

微波有机合成及反应器的新进展

简述了微波促进有机合成反应的机理 ,讨论了微波密闭合成反应技术、微波常压合成反应技术、微波连续合成反应技术及微波干法合成反应技术在近年来的进展情况。分析了家用微波炉的缺点 ,对目前国内外实验用微波反应器在有机合成应用中的不足之处进行了评价 ,结合本教研室所做的工作 ,介绍了有机合成专用微波炉。展望了微波有机合成的发展前景。     

Microwave Energy Absorption Behavior of Foamed Berry Puree Under Microwave Drying Conditions

The microwave energy absorption behavior of foamed berry puree was studied considering the variations in the physical properties of the material. The absorptions of microwave energy within foamed berry puree indicated fluctuating trends in decay as microwave drying progressed, which were attributed to the effects of temperature, moisture content, and density of the material. Mathematical models of the dielectric constant ?′ and dielectric loss factor ?″ as a function of temperature and moisture content were developed using second-order functions. During microwave drying of foamed berry puree, moisture content had the most important negative influence on the dielectric constant and dielectric loss factor, followed by temperature and porosity.     

Microwave Convective Drying of Plant Foods at Constant and Variable Microwave Power

Microwave convective drying of plant foods is a promising process due to the shorter drying time and better product quality. High microwave power decreases the drying time but causes charring of the product. In this work, microwave drying under constant and variable microwave power were compared. Temperature-sensitive products, such as plant foods, are especially affected by microwave power during the final drying period. Therefore, drying at variable microwave power was found to be a more suitable drying process. Air (temperature and velocity) has an important role during microwave drying, not only as carrier of evaporated moisture but also as it contributes to a more homogeneous and faster drying.     

Microwave defrosting of coal

In cold climates, there is great interest in restore the friability of frozen material and to prevent the material from freezing in the first place. Coke plants often employ methods based on heating frozen coal by means of some hot material, but that approach has several shortcomings. A new method based on electromagnetic energy is proposed. The influence of defrosting by microwave radiation on the properties of coal is assessed. A model of a microwave-based defrosting shed is proposed. Preliminary calculations indicate that this is an effective approach.     

微波萃取技术

介绍了一种新型的萃取方法——微波萃取及所用的试剂、设备和反应条件。通过与超声波法和索氏提取法的比较。发现微波萃取不仅有较高的回收率而且精度也很好。微波萃取具有操作时间短、溶剂量少、易于回收和自动控制水平高的特点。     

Microwave Convective Drying of Plant Foods at Constant and Variable Microwave Power

Microwave convective drying of plant foods is a promising process due to the shorter drying time and better product quality. High microwave power decreases the drying time but causes charring of the product. In this work, microwave drying under constant and variable microwave power were compared. Temperature-sensitive products, such as plant foods, are especially affected by microwave power during the final drying period. Therefore, drying at variable microwave power was found to be a more suitable drying process. Air (temperature and velocity) has an important role during microwave drying, not only as carrier of evaporated moisture but also as it contributes to a more homogeneous and faster drying.     

Heterogeneous Gas-Phase Catalysis Under Microwave Irradiation—a New Multi-Mode Microwave Applicator

The microwave-assisted gas-phase oxidation of propane over perovskite-type catalysts was studied with an intention of investigating the feasibility of the new multi-mode microwave applicator. Temperature measurement was made with IR-pyrometer and thermocouple by insertion technique. Radial and axial temperature gradients are unavoidable and partially responsible for observed rate enhancement under microwave irradiation.     

微波有机合成及反应器研究新进展

综述了近年来微波辐射技术在有机合成应用中的新进展。针对微波有机合成反应技术及专用微波反应器作了重点介绍。     

微波法合成2,5-二甲基-4-羟基-3(2H)呋喃酮的研究

以丙酮醛为原料采用微波法环化合成呋喃酮。结果表明,微波法环化不仅使环化反应时间由普通方法的３６ｈ缩短为９０ｍｉｎ,而且反应产物易分离,总收率为２５．６％     

微波辐射合成邪蒿素

在微波辐射下,以7-羟基香豆素为原料,两步合成了邪蒿素。其中在第一步反应中,首次使用KF/A12O3作为碱试剂;第二步,微波辐射,大大缩短了该步反应时间,同时考察了微波辐射时间、辐射功率、反应溶剂对产率的影响。     

微波破乳器的实验研究

对自制的800 W隧道式箱型微波破乳器进行了微波破乳实验研究. 详细考察了影响微波破乳器破乳效果的工艺参数,得出了最佳条件：流量70 L/h,温升速率16℃/min. 最佳实验条件下,含水50.0%的乳状液经微波破乳-离心分离后得到的离心油样含水率为2.2%. 循环连续破乳实验表明,含水率随有效停留时间的延长逐渐趋于稳定,采用多级串联的方法可以提高处理量,且可达到较好的破乳效果. 通过对微波破乳器的场强分布数值模拟,对比了有物料和无物料两种情况下微波破乳器的场强分布差异,为微波破乳器的进一步放大提供了依据.     

利用微波介电加热和微波干燥水解法制备TiO2微粒

利用微波介电加热和微波干燥条件下TiCl4直接水解的方法制备出平均尺寸为40m，粒径分布窄，均为球形且形态均一，团聚较少，金红石型的TiO2纳米粒子，其内部品粒平均大小为17nm。而传统加热和干燥条件下形成的纳米微粒平均为60nm，粒经大小不均一，形态较不规则，团聚严重。微波加热和干燥方法具有清洁、快速均匀高效、环境友好的优点，推广前景良好。TiCl4水解法经济便利，适于工业化生产。     

Microwave dielectrics with enhanced permittivity

Depending on the operating frequency range of modern communication systems various microwave elements are required for effective micro-miniaturization of radio equipment. In this work potential ways of developing microwave dielectrics with high permittivity are discussed. In particular, it has been shown that temperature stable microwave dielectrics with a permittivity of about 100 can be developed by either influencing the phonon spectrum by means of aliovalent substitution in the cation sublattices or by the formation of a mobile cation sublattice. However, microwave dielectrics with permittivity above 100 require the employment of polarization mechanisms related with the spontaneously polarized state. In this case an increase in permittivity is generally accompanied by an increase in dielectric loss. Chemical systems demonstrating temperature stable properties are discussed, and include those in which an increase in permittivity is accompanied by relatively low dielectric loss.     

Microwave Drying of Porous Materials

Experimental results on microwave drying of the porous particles exposed to air stream at 40°C are presented. The temperature and moisture distribution inside a particle were measured for gypsum spheres of 9, 18, 28, and 38 mm. The mass reduction was monitored during the drying process. The rate of drying and changes in temperature and moisture profiles for different drying conditions were analyzed and compared with the ones for convective drying.