摘要
为检测豆浆中固形物含量（S）,采用网络分析仪研究了频率（20～4 500 MHz）、温度（20～80℃）和S（2.00～7.01 g/（100 m L））对豆浆介电参数（相对介电常数ε＇和介质损耗因子ε″）的影响规律;建立了豆浆介电参数与温度、S之间的关系模型,并对模型预测S的可行性进行了检验。结果说明,在20～4 500 MHz的频率范围内,ε＇随频率的增大而减小,ε″随频率的增大先减小后增大,在600～2 000 MHz之间有最小值。ε＇随温度的升高而减小,低频段下ε″随温度的升高而增大,而高频段下ε″随温度的升高而减小,ε″达到最小值时的频率随着温度的升高而增大。ε＇随S的增大而减小,而ε″随S的增大而增大。一定频率下,可用二次多项式表达豆浆的ε＇和ε″与温度、S的关系;基于100 MHz下的ε＇和20 MHz下的ε″所建立的二次多项式的决定系数分别为0.989和0.990。对模型的验证结果表明,基于20 MHz下的ε″计算的S值与实测值之间的决定系数为0.978。研究结果表明介电特性可用于检测豆浆中的固形物含量。
To explore a method for detecting solids content of soybean milk,network analyzer and openended coaxial-line probe were applied to study the influence of frequency（ 20 ～ 4 500 MHz）,temperature（ 20 ～ 80℃） and solid content（ 2. 00 ～ 7. 01 g /（ 100 m L）） on dielectric parameters（ relative dielectric constant ε＇ and dielectric loss factor ε″） of soybean milk. The models describing the permittivities as functions of temperature and solid content were built,and its feasibility to predict solid content using obtained permittivities were verified. The results showed that over the frequency range of 20 ～4 500 MHz,ε＇ was decreased with an increase of frequency,and ε″ was increased after decrease with increasing frequency. The minimum ε″ was observed at 600 ～ 2 000 MHz. ε＇ was decreased with an increase of temperature,and ε″ was increased with increasing temperature at low frequency end and decreased at high frequency end. The frequency where minimum ε″ was increased with increasing temperature. ε＇ was decreased but ε″ was increased with increasing solid content. At a given frequency,quadratic polynomial could be used to describe the relationship among permittivities（ ε＇ and ε″） and temperature and solid content. The determination coefficient of the built model was 0. 989 for ε＇（ 100 MHz） and 0. 990 for ε″（ 20 MHz）. The model verification results showed that the determination coefficient was 0. 978 between the calculated solid content using obtained ε″ at 20 MHz and the measured ones. This study indicated that permittivities could be used to detect the solid contents of soybean milk.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2016年第7期239-245,共7页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(31171720)
关键词
豆浆
固形物含量
频率
温度
介电参数
soybean milk
solid content
frequency
temperature
permittivities
