Physics and Control Department, Faculty of Food Science, Corvinus University of Budapest H-1118 Budapest Somlói út 14-16. Hungary
Corvinus University of Budapest and United States Department of Agriculture, Grain Inspection Packers and Stockyards Administration Technical Services Division 10383 N. Ambassador Dr. Kansas City, MO 64153. USA
Drying yellow-dent field corn from harvest moisture levels to safe storage levels is a major cost for producers. This cost can be minimized by precise control of the final moisture content through feed-forward or feedback control. One of the difficulties in achieving control of corn drying is the inaccuracy of dielectric moisture measurements due to non-uniform moisture distributions within kernels after drying. After dried grain has equilibrated for several hours, moisture measurements are somewhat different than immediately after drying. This research examined these effects for yellow-dent field corn over a range of measurement frequencies and drying conditions. Prediction equations relating dielectric constant to moisture content were developed for a range of radio frequencies. The differences between predicted moisture values for recently dried and equilibrated corn were found to be dependent on the measurement frequency and the final moisture content of the grain. For some conditions, particularly for low measurement frequencies and high final moisture contents, predicted moisture contents increased after equilibration. However, predicted moisture values decreased upon equilibration if the final moisture content was near 15 percent, especially if the measurement frequency was between 500 kHz and 10 MHz. Higher measurement frequencies generally yielded smaller predicted moisture differences than lower frequencies.
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FUNK, D.B. (2001): An investigation of the nature of the radio-frequency dielectric response in cereal grains and oilseeds with engineering implications for grain moisture meters. Ph.D. Dissertation, University of Missouri-Kansas City. No.:3010741
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Hungarian Standard (1983): Élelmezési, takarmányozási, ipari magvak és hántolt termények vizsgálata, nedvességtartalom meghatározás. (Edible, fodder and industrial seeds and husked products. Quality test. Determination of moisture content.) MSZ 6367/3-83.