Time Dependence of Component Temperatures in Microwave Heated Immiscible Liquid Mixture

Abstract

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 (cyclohex-ane 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 °C at 300 sec of microwave heating. While the maximum value of the difference between water and cyclohexane temperatures in the mixture was 57 °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.

Key Words:

• Microwave heating
• immiscible liquids
• mixture
• temperature
• time
• wave
• mathematical model