Abstract 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.

中文翻译：

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液态圆柱反应物微波诱导平均温度的有效经验模型

摘要 微波辅助化学反应具有反应速度快、化学收率高、能耗低等诸多优点，在制备化学中非常受欢迎。然而，在专用设备中，微波单元作为“黑匣子”运行，使热效应在微波辅助化学过程中的作用有些模糊。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，用于计算代表典型微波反应器核心元件的三介质圆柱结构中的微波诱导温度，假设反应物被对流搅拌。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。为了说明它的功能，该模型用于计算在 MiniFlow 200SS 间歇式反应器中加热的水、乙醇和甲醇的时间-温度特性。为水计算的曲线似乎与实验非常吻合。这证实了间歇式反应器中液体反应物由于对流而温度均匀化的假设，并表明建模有助于澄清和量化微波辅助化学过程的细节。