Using Microwave Sensing to Investigate Kernel Moisture Content at the Front and Back of Semitrailers during Peanut Drying

Abstract

Abstract. Several factors influence the effectiveness of peanut drying. Such factors include temperature and relative humidity of the air used for aeration, air velocity through the peanuts, and the presence of foreign material that could obstruct air flow. All of these factors can vary at any location in a semitrailer holding 20 to 25 tons of peanuts being dried. Therefore, it is highly unlikely that a volume of peanuts >71 m3 (2500 ft3) will dry uniformly. During the drying process, an operator removes samples of peanuts for kernel moisture content testing every 3 to 4 h to validate the estimated drying time determined by peanut-drying models used in the peanut industry. However, if samples are only taken from one location, it is likely that other locations differ in kernel moisture content. To investigate kernel moisture content near the front and back of the semitrailer, two peanut drying monitoring systems, each equipped with a microwave moisture sensor, were deployed at a peanut buying point in central Georgia during the 2014 and 2015 peanut harvest seasons. Each system monitored in-shell kernel moisture content and drying parameters in real-time, every 12 s. In-shell kernel moisture content was determined with a standard error of prediction of 0.55% moisture when compared to the reference oven-drying moisture tests. The two monitoring systems were placed in 13.7-m (45-ft) drying semitrailers, one 3 m (10 ft) from the front and the other 3 m (10 ft) from the back. Data from the measurements were time-stamped and reconciled accordingly, and they were analyzed to compare the moisture loss in real-time at both locations in the trailer. The 12-s resolution provided a continuous moisture profile to analyze rather than the discrete profile currently provided by sampling every few hours. Results show that moisture loss, and therefore resulting kernel moisture content, can vary from one end of the trailer to the other during peanut drying. Therefore, systems that monitor peanut drying at various locations throughout the semitrailer would improve peanut drying efficiency. Keywords: Dielectric properties, In-shell kernel moisture content, Microwave sensing, Peanut drying, Real-time monitoring, Sensors.