Three dimensional radio-frequency electromagnetic imaging of an in-bin grain conditioning process

Abstract

Most cereal grains and oilseeds are harvested at temperatures and/or moisture contents that are not suitable for long-term storage. Safely storing these grains for more than a few days requires conditioning or drying of the grain, which is usually done in storage bins with ambient or heated air. While critical for safe-storage, this process is currently not closely monitored, or is monitored with point temperature/humidity sensors which are only sensitive to the grain in close proximity to the sensor. Herein, we present the use of an Electromagnetic Imaging (EMI) system that creates 3D images of the grain moisture content of the entire bin, and shows the use of the EMI system to monitor a week-long grain conditioning process in a scaled grain bin. The 3D imaging results are compared with data from three point sensors that were embedded in the bin. We further confirm the 3D experimental results with a series of simulations where the exact 3D image is known. The results show that the 3D images broadly follow the point sensors, with some image artifacts due in part to problems with modelling the point-sensor cable in the bin. These artifacts were eliminated through a post-processing algorithm that divides the image into a small number of layers and averages the results within each layer. Finally, we conclude that the EMI system is capable of monitoring the grain conditioning process, and will show when the grain has reached safe storage conditions.