Browsing by Author "Hylkilä, Taneli"

The aim of this study was to determine performance, accuracy and precision of grain moisture sensors that grain dryer company Antti-Teollisuus Ltd. had purchased and to find the most suitable location for the sensor in the dryer. The experiments of the study were accomplished in the hot-air grain dryer of the Helsinki University research farm. The sensors were installed to the dryer and to the continuous sample collector device. Grain moisture content (MC) data from the sensors was compared with the MC determined from the oven dried samples which were taken near sensors locations, during the drying process. Performance of the sample collector and sensors was examined and the effect of the sample collector’s structure to measurement results was analysed. Data was collected from ten drying batches in total. The crops used in experiments were wheat, barley, fababean, oats and pea-oats mixture. A sensor in the dryer fouled many times during the experiments and therefore gave invalid measurement results. Another sensor in the dryer had low precision with a random error of 2.3 %-points of MC. The most precise results were given by the sensor in continuous sample collector. Random error of the sensor in the sample collector was 0.3 %-points of MC which is acceptable error in grain dryer application. This sensor was recalibrated with results from the oven dried samples. Recalibrated accuracy was 0.13%-points of MC in the first wheat drying batch. After the drying experiments it was noticed that sample collector’s structure had distorted results by giving too low MC readings. The problem was solved by the recalibration of the sensor. During the experiments it was also noticed that grain in the sample collector contained slightly more debris than the grain elsewhere in the grain dryer. Effect of this debris, which contained mainly small weed seeds, was however estimated insignificant. Results from this study indicate that the examined moisture sensor and sample collector are suitable for operation in practical hot-air grain dryer conditions. To ensure measuring accuracy, regular calibration is needed. New calibration factors for wheat were calculated from the results. With these factors, wheat MC can be calculated, when sample collector with the current design and dimensions is used. According to the results from this study, a precise continuous grain MC measurement is possible to accomplish with the designed sample collector. This accurate on-line grain MC measurement enables a new kind of real-time control of the grain drying process for enhanced performance and efficiency of the dryer.