基于微波干燥的江南年糕介电特性的研究

Effect of Microwave Drying on the Dielectric Properties of Jiangnan Rice Cakes

摘要:

本文以江南年糕为对象，利用网络分析仪测量并研究了频率（915~2450 MHz）、年糕含水率（16~48%）和温度（25~60 ℃）对相对介电常数ε′和介质损耗因数ε″的影响；计算了微波穿透深度并分析频率、含水率和温度对其影响；建立了部分频率下年糕介电参数与主要影响因素的关系模型，检验了基于介电参数预测含水率的精度和可行性。结果表明，在915~2450 MHz频率段内，年糕的 ε′随频率的增大而减小，ε″随频率的增大而增加，ε′和ε″均随含水率的增大而增加，但随温度的增大而减小；能量穿透深度随含水率、频率的升高而降低，随温度的升高而增加。可用二元三次方程描述介电参数和主要影响因素的关系，且各模型的决定系数皆大于0.99。本研究对了解年糕的介电特性以及含水率检测仪的开发有重要的指导意义。

Abstract:

Jiangnan rice cakes were used as the object in this study, and a network analyzer was used to determine the effects of frequency (915~2450 MHz), moisture content of rice cakes (16~48%), and temperature (25~60 ℃) on the relative permittivity ε' and dielectric loss factor ε". The microwave penetration depth was calculated and the impacts of frequency, moisture content, and temperature on the microwave penetration depth were analyzed. A relationship model between dielectric parameters of rice cakes and the main factors at some frequencies was established to examine the accuracy and feasibility of moisture content prediction based on the dielectric parameters. The results showed that in the frequency range of 915~2450 MHz, ε' of rice cakes decreased and ε" increased with increasing frequency; both ε' and ε" increased with increasing moisture content, but decreased with increasing temperature. The value of energy penetration depth decreased with increasing moisture and frequency, and increased with increasing temperature. The relationship between dielectric parameters and the main influencing factors could be described by binary cubic functions, and the coefficients of determination of all models were greater than 0.99. These findings would have an important guiding significance on understanding the dielectric properties of rice cakes and developing moisture detectors.