Abstract
Dielectric properties are important characteristic parameters in the microwave-assisted application of hygroscopic agricultural media. To break through the limitation of traditional general effective medium (GEM) formula and develop the new calculation formula suitable for agricultural products, a modified formula, that is, modified general agricultural products effective medium (abbreviated as MGAPEM) formula, was presented in this study for the dielectric property calculation of granular agricultural products in the microwave band. The correctness, validity, and accuracy of MGAPEM formula were verified by using literature and experimental measurement data. Results show that the maximum errors of the dielectric constant and dielectric loss factor are 0.42% and 0.98%, respectively, in the conditions of microwave frequency (2.0–12.2 Ghz) and moisture content (2.0%-19.7%, wet basis). The accuracy of MGAPEM is higher than some traditional theoretical formulas. The MGAPEM formula provides a theoretical formula for the dielectric property analysis of granular agricultural products in the microwave band at room temperature (24℃).
Highlights
Dielectric properties are important parameters in microwave-assisted applications of hygroscopic agricultural media
Nelson used several different dielectric mixing equations and linear extrapolation functions to analyse the dielectric properties of granular agricultural products, and the results showed that the Landau–Lifshitz–Looyenga(LLL) equation is considered suitable for the analysis of the dielectric properties of grain-like particulate matter
The comparative analysis shows that when E =0.45 and A are equal to 5.6, 5.7, 5.9, 6.0, 6.1, 6.2, and 6.3, the calculation result of the MGAPEM formula is consistent with the LLL equation and (Hc)1/3 vs U function
Summary
Dielectric properties are important parameters in microwave-assisted applications of hygroscopic agricultural media. The early models and theoretical studies of the dielectric properties of granular agricultural products mainly focused on the analysis of the linear relationship between the dielectric properties and density and the dielectric mixing equation of the two-component gas– solid (air and particle) mixture [5]. The obtained expression is not general, and this expression is almost a formula for a class of particulate matter, and it cannot be used to predict the dielectric properties of other types of granular agricultural products; the prediction error of some expressions is relatively large (3.0%–10.0%)[5]. A large error between the predicted and the measured values can still be observed even if the famous Maxwell–Garnett, Bruggeman, Lichtenecker, and other mixed equations are used to predict the dielectric properties of agricultural products [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
