Miller Magazine Issue: 139 July 2021

56 COVER STORY MILLER / july 2021 1) Basic rule: aerate when ambient temperature is at least 10 °C lower than grain temperature. 2) Aerate in the daily hours where the outside tempera- ture and relative humidity are close to the average values (See fig. 8). 3) Asses a target moisture content for the grain preserva- tion and take advantage of the EMC (equilibrium moisture content) charts to understand when the outside conditions are suitable for aeration. 4) Following the seasonal variations of the ambient tem- perature in temperate climates, keeping in mind the low thermal conductivity of the grain, it is possible to plan the storage operations in order to limit (even kill or stop) the insect activity. This is a typical method used also along with refrigerators. In the case that bad management of the grain has taken place, these are some signals that can be detected during storage: 1) High temperature readings (so called “Hotspots”) in some localized sensor only within the grain bulk usually a key signifier of insect infestation. 2) Strong weight difference (reduction) between the in- coming quantity stored and the delivered grain is signal of insect’s activity. 3) Product sticking on the sidewall sheets after the un- load is usually sign of moisture migration within the grain pile, humidity condensation on the roof or excessive mois- ture of the grain. FUTURE VISION & RECENT MARKET TRENDS Roof natural ventilation There is always a top to bottom temperature gradient in- side the bin roof, as the hot and moist air tend to concentrate naturally to the top. By having a gap on the roof peak as well as on the eave perimeter it is possible to allow the hot air to be released to the atmosphere and replaced with fresh air entering from the eave. This natural ventilation prevents the roof from sweating. There is also no need for a roof exhauster, therefore removing energy consumption and management. When the aeration system is operational the natural air- flow stops and allow the air in excess to be released from both peak and eave gaps, and it will restart as soon as the temperature gradient is in place again. Monitoring systems Basic systems only monitor the temperature of the grain bulk and struggle to provide the best distribu- tion and quantity of sensors needed to detect “hot spots” accurately. “Hot spots” are where insects are actively spoiling the product. Recent advancements in grain bin monitoring sys- tems provide temperature cables as well as a humidity and CO2 cable. These are able to detect insect activity with more accuracy by measuring the CO2 concentra- tion and its relative variations. Implementing a weather station and additional computer technologies allow for a complete auto- mated system, with the capability to start the fan when the outer air conditions are suitable for the business needs without the need of human su- pervision. With this, operational savings are also possible. AGI offers a range of safety and temperature sensing systems that are available with cloud-based functional- ity for remote controlling and alarm. Figure 8 Figure 9 Figure 10