Yang Chuqiao, Yakovlev Vadim V
J Microw Power Electromagn Energy. 2013;47(3):177-85. doi: 10.1080/08327823.2013.11689856.
Microwave-assisted chemical reactions have become very popular in preparative chemistry due to many advantages such as accelerated reaction rate, higher chemical yield and lower energy use. In dedicated equipment, however, the microwave units operate as "black boxes" keeping the role of the thermal effects in microwave-assisted chemical processes somewhat obscure. To address this issue, in this paper, we propose a simple mathematical model for computing microwave-induced temperature in a three-media cylindrical structure representing a core element of a typical microwave reactor with the reactant assumed to be stirred by convection flows. The model determines the average temperature of the reactant for the known absorbed microwave power and heating time. To illustrate its functionality, the model is used to compute time-temperature characteristics of water, ethanol, and methanol heated in the batch reactor MiniFlow 200SS. The curve calculated for water appears to be in an excellent agreement with an experiment. This confirms the hypothesis on temperature homogenization in liquid reactants in batch reactors due to convection and suggests that modeling can be helpful in clarifying and quantifying the details of microwave-assisted chemical processes.
由于具有加速反应速率、提高化学产率和降低能源消耗等诸多优点，微波辅助化学反应在制备化学中已变得非常普遍。然而，在专用设备中，微波装置就像“黑匣子”一样运行，使得热效应在微波辅助化学过程中的作用有些模糊不清。为了解决这个问题，在本文中，我们提出了一个简单的数学模型，用于计算在一个三介质圆柱形结构中的微波感应温度，该结构代表典型微波反应器的核心元件，假设反应物由对流流动搅拌。该模型根据已知的吸收微波功率和加热时间确定反应物的平均温度。为了说明其功能，该模型用于计算在间歇式反应器MiniFlow 200SS中加热的水、乙醇和甲醇的时间-温度特性。计算得到的水的曲线与实验结果非常吻合。这证实了关于间歇式反应器中液体反应物由于对流而实现温度均匀化的假设，并表明建模有助于阐明和量化微波辅助化学过程的细节。
