Kennedy Alvin, Reznik Aron, Tadesse Solomon, Nunes Janine
Dept. of Chemistry, Morgan State University, Baltimore, MD, USA.
J Microw Power Electromagn Energy. 2009;43(2):52-62. doi: 10.1080/08327823.2008.11688612.
Measured influence of microwave heating on time dependencies of component temperatures for two immiscible liquids in a mixture shows differences for polar (water) and non-polar (cyclohexane or carbon tetrachloride) liquids. The rate of increase for the temperature of water with time of microwave heating is larger than other liquids in the mixture (maximum rate of temperature growth for water is 8 times larger than corresponding rate for carbon tetrachloride and 2 times larger than cyclohexane). This leads to creating, for a considerable time period, a unique environment where there is a significant temperature difference between two liquids in a mixture. The maximum value of the difference between water and carbon tetrachloride temperatures in the mixture was 107 degrees C at 300 sec of microwave heating. While the maximum value of the difference between water and cyclohexane temperatures in the mixture was 57 degrees C at 135 sec microwave heating. This suggests that electromagnetic waves lose most of their energy to polar liquids (water), while the difference in rates of temperature growth for carbon tetrachloride and cyclohexane can be explained by different mechanisms of heat transfer from water to cyclohexane (conduction and convection) and to carbon tetrachloride (conduction only). Semi-empirical mathematical models for the time dependencies of temperature growth for components of the mixtures gave good correlation with experimental data (relative error less than 9%). These results can be used to model the temperature kinetics of components for other multi-phase immiscible liquid mixtures.
微波加热对混合物中两种不互溶液体组分温度随时间变化的影响测量结果表明，极性液体（水）和非极性液体（环己烷或四氯化碳）存在差异。微波加热时，水的温度随时间的升高速率比混合物中的其他液体大（水的最大温度增长率比四氯化碳相应速率大8倍，比环己烷大2倍）。这导致在相当长的一段时间内形成一种独特的环境，即混合物中两种液体之间存在显著的温度差。在微波加热300秒时，混合物中水和四氯化碳的温度差最大值为107℃。而在微波加热135秒时，混合物中水和环己烷的温度差最大值为57℃。这表明电磁波将大部分能量传递给了极性液体（水），而四氯化碳和环己烷温度增长率的差异可以通过水向环己烷（传导和对流）以及向四氯化碳（仅传导）的不同热传递机制来解释。混合物各组分温度增长随时间变化的半经验数学模型与实验数据具有良好的相关性（相对误差小于9%）。这些结果可用于模拟其他多相不互溶液体混合物各组分的温度动力学。
