Often, our representatives are asked about what IntelliFarms' take is on freezing grain during the winter months. While this is a common practice, which many have made an annual part of their management approach, IntelliFarms typically takes an anti-freeze stance.
It all comes down to condensation. When freezing, more moisture is trapped within the bin rather than pushed out to get the grain/interspacial air to be at the grain's unique equilibrium moisture content (EMC) for quality management. While this can be manageable when outdoor/ambient temperatures are also below freezing, the concern comes when temperatures begin to warm above that freezing mark. The chart below illustrates two scenarios taken from real experiences. While both grain temperatures are technically below 32ºF, this chart illustrates the difference even a few degrees colder can make in managing grain safely.
In Scenario 1, you see that because the grain/interspacial air temperature is slightly warmer, when the 40ºF ambient temperatures come in contact with the 25ºF, the relative humidity created in the bin is only 50%, causing the dewpoint temperature to only be 22.8ºF. Because the dewpoint temperature is less than the grain/interspacial temperature, it does not cause a condensation issue. The second scenario is different. The warmer outside air, causes the dewpoint temperature to become 27.2ºF, which then causes condensation issues when this warmer air comes in contact with the 20ºF grain. Thus, an icy crust develops on the top of the grain, posing risk of spoilage.
In addition, this increased condensation within the bin has the ability to ice over and cover the roof vents. If fans were to run without the knowledge that the vents are blocked by ice, that's when you run into issues with "blowing out the roof" of bins. We hear about it every year, and it's not a pretty picture.
In conclusion, IntelliFarms recommends that you think twice about holding your grain below freezing. You hear often about a 20ºF goal, but that trapped excess moisture at that temperature carries big risks. Tips from IntelliFarms on managing condensation during these colder winter months include:
Cover the fan opening when the fan is turned off.
Aerate the grain and keep the grain temperature as uniform as possible. Avoid temperature differences of more than 10ºF within the grain and more than 20ºF between the grain and the outside air temperature. Non-uniform grain temperature can be identified and monitored by using monitoring cables installed in the bins.
During aeration, air of the appropriate equilibrium moisture content will need to be pushed through the mass to avoid moisture loss (and ultimately, money) during aeration. A controlled and automated system like BinManager selectively runs fans when appropriate and productive air is available, minimizing risk of over-drying the grain.
No two bin management scenarios are the same. And there can be some rare exceptions to this freezing grain role, based on unique commodity characteristics and scenarios. We always encourage your questions and concerns to be brought to us at IntelliFarms, and together we can work to counsel and find solutions that help you meet your delivery and quality goals.