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Real-time Monitoring of Moisture within an Eighth-scale Grain Bin during Drying

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2018 ASABE Annual International Meeting  1801664.(doi:10.13031/aim.201801664)
Authors:   Micah A. Lewis, Samir Trabelsi, Stuart O. Nelson
Keywords:   Dielectric properties, Grain drying bin, Moisture content, Microwave sensing, Real-time monitoring, Sensors

Abstract. After cereal grain and oilseed are harvested, they are stored and dried in large cylindrical storage bins. Such bins can have a diameter ranging from 4.6 to 18.3 m and height ranging from 4.6 to 28.7 m. Grain or oilseed within the bins are dried by forcing ambient or heated air up through them. The moist air escapes through vents in the conical roof. Since the contents of the bin can be more than 15.2 m deep, a significant problem in grain and oilseed drying is overdrying the bottom layer while trying to dry the top layer. This is due to insufficient knowledge of moisture throughout the bin. Presently, an operator probes certain locations to determine moisture content; however, the locations that are reachable are limited. Also, since such probing is done daily or every few days, moisture content determination is not frequent enough to observe the dynamics of moisture content within the bin continuously. By using a microwave moisture sensor operating at 5.8 GHz, developed within USDA ARS, the moisture content of the grain or oilseed can be measured continuously at multiple locations, providing real-time moisture content with 12-second resolution during drying. An automated, eighth-scale grain drying system was developed with microwave moisture sensors at different heights within the bin to observe moisture migration as grain or oilseed dried. Samples were extracted for moisture tests by the reference oven drying method to assess the accuracy of moisture content determined by the microwave sensors. Overall evaluation showed that the automated grain drying system is an effective solution for real-time monitoring of moisture content during drying.

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