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ARS Home » Research » Publications at this Location » Publication #91233
Title: NONDESTRUCTIVE MICROWAVE CHARACTERIZATION FOR BULK DENSITY AND MOISTURE CONTENT DETERMINATION IN SHELLED CORN

Author
item TRABELSI, SAMIR - OICD
item KRASZEWSKI, ANDRZEJ
item NELSON, STUART

Submitted to: Measurement Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Moisture content of grain at harvest, when going into storage, or when being traded, transported, or processed is one of the most important quality characteristics that must be determined. Currently, samples of grain lots or shipments are taken at various points for moisture determination by electrical or electronic grain moisture meters. There is need for new techniques that can provide reliable moisture content information on-line for moving grain. Such capability would be very helpful in automated systems everywhere in the grain industry. A problem with implementing electronic sensing of grain moisture content is the variation in bulk density, or packing, of the grain as it moves in a conveyor. This research reports a technique for sensing moisture content of corn from instantaneous measurement of the dielectric properties (electrical characteristics) of the grain, from which both the moisture content and the bulk density of the grain can be rapidly determined. Thes measurements at microwave frequencies provided corn moisture contents within about « of one percent moisture content, and bulk densities were given within less than 2 percent accuracy. Development of practical monitoring equipment, based on these techniques, would provide new tools for maintaining and improving the quality of grain and grain products for domestic use and for export.

Technical Abstract: A method based on nondestructive microwave characterization is used for simultaneous determination of bulk density and moisture content in shelled corn. This method can be applied regardless of the measurement technique and thus considerably simplifies the calibration procedure. Calibration equations, for both bulk density and moisture content, are given, along with the standard error of performance (SEP) at several frequencies, between 11 and 18 GHz, and three temperatures, 14, 24 and 34 degrees C. The bulk density, ranging from 695 to 830 kg per cubic meter, can be determined with SEP between 11 and 15 kg per cubic meter. Neither sample moisture content nor its temperature are required to determine bulk density. The moisture content ranging from 9% to 19%, wet basis, can be determined at each temperature without knowledge of bulk density with SEP of less than 0.5% moisture. Results of an error analysis of the measurements show that about half of the total uncertainties in bulk density and moisture content can be considered systematic errors and thus they are correctable.