一种具有搅拌桨的微波夹层反应釜内多物理场特性研究

Study of multi-physical field characteristics in a microwave reactor with an interlayer and a stirring blade

微波加热化学反应速度快、效率高,因此微波反应器被应用于辅助化工生产中。然而,加热不均匀是目前微波加热化学反应的主要问题,因此在微波夹层反应釜内引入流体搅拌桨,并采用COMSOL仿真软件将麦克斯韦方程、传热方程和流动方程进行多物理场耦合计算,探讨物料介电特性、微波功率和搅拌桨参数对微波加热特性的影响,研究发现:(1)当物料的相对介电常数在(2.16-0.28j)~(2.73-0.13j)之间时,微波加热均匀性较好;(2)加热2 s后,微波加热均匀性呈现出规律性变化;(3)随着微波功率的增大,相同加热时间下物料温升变快,但搅拌功耗也越高;(4)叶轮直径和搅拌转速越大,物料的温度变异系数越低,微波加热均匀性越好;变异系数随着叶轮离底间隙的增大先减小后增大,功耗随着离底间隙的增大线性减小;(5)搅拌桨参数对功耗和温度变异系数影响的显著性为:搅拌转速>叶轮直径>离底间隙。

Microwave heating chemical reaction is fast and efficient, so microwave reactors are used in auxiliary chemical production. However, uneven heating is the main problem of microwave heating chemical reaction. Therefore, a fluid stirring paddle was introduced into a microwave reactor with an interlayer. The multi-physics coupling calculation of the Maxwell equation, heat transfer equation and flow equation was carried out using COMSOL software, and the influence of material dielectric properties, microwave power and stirring paddle parameters on microwave heating characteristics were discussed. The study found that:(1) When the relative dielectric constant of the material is between(2.16-0.28j) and(2.73-0.13j), the microwave heating uniformity is better;(2) After heating 2 seconds, the uniformity of microwave heating shows regular changes;(3) With the increase of microwave power, the material temperature rises faster under the same heating time, but the stirring power consumption is also higher;(4) The larger the impeller diameter and stirring speed, the lower the temperature variation coefficient of the material, and the better the microwave heating uniformity;The coefficient of variation first decreases and then increases with the increase of the bottom clearance, and the power consumption decreases linearly with the increase of the bottom clearance;(5) The significance of the stirring blade parameters influence on power consumption and coefficient of variation is: stirring speed > impeller diameter > bottom clearance.