基于介质损耗因数的红小豆含水率测量方法研究

以红小豆为对象,研究测量信号频率(1kHz～1MHz)、含水率(13.8%～21.8%)、容积密度(747～851kg/m3)和温度(5～40℃)对介质损耗因数的影响规律,从理论上分析介质损耗因数的变化原因,建立500kHz条件下红小豆的介质损耗因数、容积密度和温度与含水率的数学模型,并验证模型的正确性。结果表明:在1kHz～1MHz频段内,红小豆的介质损耗因数随测量信号频率的增大而减小,却随含水率、容积密度和温度的增大而增大;可用三元二次方程表征含水率与介质损耗因数、容积密度和温度之间的关系,模型的决定系数为0.9882。

Determination of Water Content in Small Red Beans Based on Dielectric Loss Factor

A mathematical model for water content of small red beans with respect to relative dielectric loss factor,bulk density and temperature was set up and validated under a signal frequency of 500 kHz.The effects of measurement signal frequency(1 kHz-1 MHz),bulk density(747-851 kg/m3) and temperature(5-40 ℃) on relative dielectric loss factor were studied,and the mechanism underlying the change in relative dielectric loss factor was analyzed in theory.The results indicated that dielectric loss factor of small red beans revealed a decreasing trend with increasing signal frequency in the range of 1 kHz-1 MHz,but presented an opposite trend as the water content,bulk density and temperature increased.A quadratic model characterizing the relationship of water content with relative dielectric loss factor,bulk density and temperature was established with a determination coefficient of 0.9882.