微波频段下麦麸介电特性的测量与分析

doi:10.13304/j.nykjdb.2023.0653

摘要/Abstract

摘要：

介电特性对于麦麸的微波消杀与干燥具有重要研究价值，为探究麦麸的介电特性，在频率0.5~4.0 GHz、含水率1.94%~31.56%、温度35~85 ℃下，采用同轴传输/反射法测量了麦麸介电常数 $ε'$ 和损耗因子 $ε$ ″的变化，并采用多元回归分析法建立了频率为2.45 GHz的 $ε'$ 、 $ε$ ″与含水率和温度的数学模型。结果表明：随着频率的增加， $ε'$ 和 $ε$ ″呈单调递增状态；温度越高， $ε'$ 和 $ε$ ″越大；含水率越高， $ε'$ 和 $ε$ ″越大。对模型的验证结果表明， $ε'$ 和 $ε$ ″实验值与计算值之间的决定系数分别为0.993 12和0.990 82，相对误差分别小于7%和10%，说明该模型可以较好地预测麦麸介电特性。研究结果为麦麸物理性质相似物质的介电特性测量提供指导，对麦麸微波干燥与微波消杀等设备的研发提供理论依据与数据支持。

关键词: 麦麸, 传输/反射法, 介电特性, 微波频段

Abstract:

Dielectric properties play important roles in microwave sterilization and drying of wheat bran. In order to explore the dielectric properties of wheat bran， the coaxial transmission/reflection method was used to measure the change of dielectric constant ε' and loss factor ε″ of wheat bran at the frequency of 0.5~4.0 GHz， moisture content of 1.94%~31.56% and temperature of 35~85 ℃. The mathematical model of ε'and ε'' with moisture content and temperature of 2.45 GHz was established by multiple regression analysis. The results showed that $ε'$ and $ε$ ″ monotonically increased with the increase of frequency； the higher the temperature was， $ε'$ and $ε$ ″ were larger； the higher the moisture content， $ε'$ and $ε$ ″ were larger. The verification of the model showed， the determination coefficient between the measured value and the calculated value of the dielectric property was 0.993 12 and 0.990 82， respectively， and the relative error was less than 7% and 10%， which indicated that the mathematical model can better calculate the dielectric property of wheat bran. The results provided guidance for the measurement of dielectric properties of substances with similar physical properties of wheat bran， and provided theoretical basis and data support for the research and development of microwave drying and microwave killing equipment of wheat bran.

Key words: wheat bran, transmission/reflection method, dielectric property, microwave frequency band

中图分类号:

S377

王豪, 方兵, 叶大鹏, 谢立敏. 微波频段下麦麸介电特性的测量与分析[J]. 中国农业科技导报, 2024, 26(12): 115-121.

Hao WANG, Bing FANG, Dapeng YE, Limin XIE. Measurement and Analysis of Dielectric Properties of Wheat Bran at Microwave Frequency[J]. Journal of Agricultural Science and Technology, 2024, 26(12): 115-121.

图/表 6

图1 测试系统

Fig. 1 Test system

图2 不同含水率下频率对麦麸介电常数与损耗因子的影响

Fig. 2 Effect of frequency on the dielectric constant and loss factor of wheat bran under different moisture content

图3 不同温度下不同含水率麦麸的介电常数与损耗因子

Fig. 3 Dielectric constant and loss factor of wheat bran with different temperatures at different moisture content

图4 不同含水率麦麸在不同温度下的介电常数与损耗因子

Fig. 4 Dielectric constant and loss factor of wheat bran with different moisture content at different temperatures

表1 介电常数和损耗因子回归模型方差分析

Table 1 Variance analysis of permitivity and loss factor regression model

模型 Model	方差来源 Source	平方和 Sum of square	自由度 df	均方 Mean square	F值 F value	P值 P value	显著性 Significance
$ε'$ ：介电常数 Dielectric constant	模型Model	143.530 0	9	15.950 0	181.360 0	<0.000 1	**
	T	0.873 1	1	0.873 1	9.930 0	0.019 8	*
	W	0.887 8	1	0.887 8	10.100 0	0.019 1	*
	TW	7.780 0	1	7.780 0	88.450 0	<0.000 1	**
	$T 2$	0.018 0	1	0.018 0	0.204 3	0.667 2
	$W 2$	3.890 0	1	3.890 0	44.270 0	0.000 6	**
	$T 2 W$	0.002 1	1	0.002 1	0.024 1	0.881 8
	$W 2 T$	0.599 7	1	0.599 7	6.820 0	0.040 0	*
	$T 3$	0.153 6	1	0.153 6	1.750 0	0.234 4
	$W 3$	0.006 9	1	0.006 9	0.078 4	0.788 9
	残差Residual	0.527 6	6	0.087 9
	失拟项 Lack of fit	0.049 1	1	0.049 1	0.513 4	0.505 7
	纯误差 Pure error	0.478 5	5	0.095 7
	总和 Cor total	144.060 0	15
$ε$ ″：损耗因子 Loss factor	模型 Model	7.140 0	9	0.793 8	620.290 0	<0.000 1	**
	T	0.064 8	1	0.064 8	50.610 0	0.000 4	**
	W	0.019 7	1	0.019 7	15.400 0	0.007 8	**
	TW	0.286 0	1	0.286 0	223.490 0	<0.000 1	*
	$T 2$	0.015 4	1	0.015 4	12.070 0	0.013 2	*
	$W 2$	0.076 6	1	0.076 6	59.890 0	0.000 2	**
	$T 2 W$	0.011 9	1	0.011 9	9.320 0	0.022 4	*
	$W 2 T$	0.001 1	1	0.001 1	0.880 8	0.384 2
	$T 3$	0.007 9	1	0.007 9	6.200 0	0.047 2	*
	$W 3$	0.004 8	1	0.004 8	3.760 0	0.100 4
	残差 Residual	0.007 7	6	0.001 3
	失拟项 Lack of fit	0.001 6	1	0.001 6	1.360 0	0.296 9
	纯误差 Pure error	0.006 0	5	0.001 2
	总和 Cor total	7.150 0	15

表1 介电常数和损耗因子回归模型方差分析

Table 1 Variance analysis of permitivity and loss factor regression model

模型 Model	方差来源 Source	平方和 Sum of square	自由度 df	均方 Mean square	F值 F value	P值 P value	显著性 Significance
$ε'$ ：介电常数 Dielectric constant	模型Model	143.530 0	9	15.950 0	181.360 0	<0.000 1	**
	T	0.873 1	1	0.873 1	9.930 0	0.019 8	*
	W	0.887 8	1	0.887 8	10.100 0	0.019 1	*
	TW	7.780 0	1	7.780 0	88.450 0	<0.000 1	**
	$T 2$	0.018 0	1	0.018 0	0.204 3	0.667 2
	$W 2$	3.890 0	1	3.890 0	44.270 0	0.000 6	**
	$T 2 W$	0.002 1	1	0.002 1	0.024 1	0.881 8
	$W 2 T$	0.599 7	1	0.599 7	6.820 0	0.040 0	*
	$T 3$	0.153 6	1	0.153 6	1.750 0	0.234 4
	$W 3$	0.006 9	1	0.006 9	0.078 4	0.788 9
	残差Residual	0.527 6	6	0.087 9
	失拟项 Lack of fit	0.049 1	1	0.049 1	0.513 4	0.505 7
	纯误差 Pure error	0.478 5	5	0.095 7
	总和 Cor total	144.060 0	15
$ε$ ″：损耗因子 Loss factor	模型 Model	7.140 0	9	0.793 8	620.290 0	<0.000 1	**
	T	0.064 8	1	0.064 8	50.610 0	0.000 4	**
	W	0.019 7	1	0.019 7	15.400 0	0.007 8	**
	TW	0.286 0	1	0.286 0	223.490 0	<0.000 1	*
	$T 2$	0.015 4	1	0.015 4	12.070 0	0.013 2	*
	$W 2$	0.076 6	1	0.076 6	59.890 0	0.000 2	**
	$T 2 W$	0.011 9	1	0.011 9	9.320 0	0.022 4	*
	$W 2 T$	0.001 1	1	0.001 1	0.880 8	0.384 2
	$T 3$	0.007 9	1	0.007 9	6.200 0	0.047 2	*
	$W 3$	0.004 8	1	0.004 8	3.760 0	0.100 4
	残差 Residual	0.007 7	6	0.001 3
	失拟项 Lack of fit	0.001 6	1	0.001 6	1.360 0	0.296 9
	纯误差 Pure error	0.006 0	5	0.001 2
	总和 Cor total	7.150 0	15

图5 麦麸介电特性实测值与计算值

Fig. 5 Correlation between measured and calculated dielectric properties of wheat bran

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[2]	刘芳宏,刘静,刘梅英,牛智有* . 颗粒饲料介电特性研究及含水率模型建立[J]. 中国农业科技导报, 2019, 21(5): 85-94.
[3]	钟汝能1,郑勤红1,2*,姚斌2,向泰1. 微波频段下颗粒状农产品的介电特性测量与分析[J]. 中国农业科技导报, 2019, 21(12): 68-75.