Measurement and Analysis of Dielectric Properties of Wheat Bran at Microwave Frequency
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.
wheat brantransmission/reflection methoddielectric propertymicrowave frequency band
国家科技期刊平台
NSTL
万方数据
