Distribution of Brick- Versus Spherical-Shaped Wireless Sensors as a Function of Gravity-Filling a Storage Silo and their Recovery from the Corn Grain Mass during Unloading

Highlights Brick-shaped wireless sensors tended to settle about 1/3 of a silo diameter around the center of the peaked grain mass whereas spherical-shaped wireless sensors tended to settle about 3/4 of a silo diameter from the center of the peaked grain mass (and within ¼ diameter of the silo wall). A mix of both spherical- and brick-shaped sensors of different sizes and weights can be used to achieve targeted placement of wireless sensors within the stored grain mass as a function of gravity filling silos of different sizes. Abstract. The most utilized automated stored grain bulk monitoring technology relies on temperature sensors incorporated into steel cables that are suspended from the roof to the floor of silos. However, cable-based sensors are expensive and require reinforcing roofs to account for the frictional forces exerted by the grain mass on the cables during loading, settling and unloading. Two shapes of wireless sensors (brick and spherical) were studied as an alternative. In-silo experiments investigated the distribution of wireless sensors as a function of gravity filling a farm silo and recovering the sensors during unloading. In the first experiment, five of each sensor shape (brick and spherical) were placed one at a time in a grain stream flowing repeatedly at 28.6 and 39.6 metric tons per hour (MT/h). The drop-out height was 5.30 m in the first and 3.94 m in the second trial. The results indicate that the brick-shaped wireless sensors tended to settle about 1/3 of a silo diameter around the center of the peaked grain mass whereas the spherical-shaped wireless sensors tended to settle about 3/4 of a silo diameter from the center of the peaked grain mass (and within ¼ diameter of the silo wall). In the second experiment, 44, 15, 20, and 25 wireless sensors were randomly placed, respectively, in the grain mass to test their recapture rate during four unloading trials. The results indicated that all wireless sensors were recovered resulting in a 100% recapture rate. Key findings of this study point toward the need for a mix of both spherical- and brick-shaped sensors of different sizes and weights to achieve targeted placement and greater distribution of wireless sensors within the stored grain mass as a function of gravity filling silos of different sizes. Keywords: Brick shape sensor, Grain quality, Sensor distribution, Sensor recovery, Spherical shape sensor.