Abstract:

Based on designing interdigital electrode capacitance detecting element,a vacuum dielectric testing system was constructed.Dielectric properties variation regularity of corn were studied and provided a foundation for process testing and control in vacuum drying.The results show that there were nonlinear correlation between the dielectric properties,temperature and vacuum.Dielectric constant and dielectric loss factor increases with vacuum degree and there curves shows similar “Z” shape and dielectric loss angle shows tangent reverse similar “Z” shape.Moisture content and temperature have great influence to dielectric properties;they were negative linear correlation with dielectric loss angle tangent.Moisture content has positive linear correlation with dielectric constant in the prime range of moisture content.The higher moisture is,the more distinct changes;Temperature has positive linear correlation with dielectric constant;Dielectric loss factor has a sharp drop with moisture content increasing and has an increasing tendency with temperature.

Key words: agricultural engineering, vacuum, interdigital electrode, corn dielectric properties