Using a Microwave Sensor for Simultaneous, Real-time Determination of Multiple Independent and Dependent Drying Parameters Within an Eighth Scale Grain Drying System

Authors: Lewis, Micah; Trabelsi, Samir

Submitted to: Drying Technology: An International Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2025
Publication Date: 12/4/2025
Citation: Lewis, M. A., & Trabelsi, S. (2025). Using a microwave sensor for simultaneous, real-time determination of multiple independent and dependent drying parameters within an eighth-scale grain drying system. Drying Technology, 43(15-16), 2357-2366. doi:10.1080/07373937.2025.2594118
DOI: https://doi.org/10.1080/07373937.2025.2594118

Interpretive Summary: Seed and grain samples such as wheat, corn, and soybean must be dried to acceptable levels of moisture content while they are stored in silos to prevent spoilage. As the products dry, heat and moisture are transferred to and from the product; therefore, the mass and volume of the product decreases. While certain parameters such as moisture content and bulk density can be measured in real-time, parameters such as shrinkage and mass reduction are not determined until drying is complete. However, knowledge of such parameters in real-time would aid in monitoring the product’s quality. USDA ARS researchers have developed a microwave sensor capable of simultaneously measuring moisture content, bulk density, shrinkage, mass reduction, and bed height. The functionality of the sensor was demonstrated in a bed of wheat that dried from 17.6% to 7.4% moisture content within an eighth-scale grain drying system in the laboratory. Implementation of this technology in the field can aid in the preservation of quality and the minimization of underdrying and overdrying.

Technical Abstract: It is important that oilseeds and cereal grain be dried to ideal moisture content as they are stored in silos and grain bins to avoid quality degradation. During drying, mass and heat transfer phenomena occur simultaneously as moisture is removed; thus, decreasing the mass and volume of the product. While certain parameters such as moisture content and bulk density can be measured in real-time, parameters such as shrinkage and mass reduction are not determined until drying is complete. Knowledge of such parameters in real-time would aid in monitoring the product’s quality. Therefore, a microwave sensor, developed within USDA ARS, was used to simultaneously determine moisture content, bulk density, shrinkage, mass reduction, and bed height of a bed of wheat as it dried from 17.6% to 7.4% moisture content (wet basis) within an eighth-scale grain drying system. Knowledge of such parameters in real-time would be helpful in minimizing underdrying and overdrying.