The grains are hygroscopic, so they lose or absorb moisture to maintain balance with the air. In this way, the moisture content of the different parts of the grain mass is unified. Such balancing occurs relatively quickly. When the grains are cooled, for example, after drying, they compress moisture from the ambient air, and the moisture content in the grain rises. To avoid this, when the grain is dried in hot air and cooled, it must be well ventilated.
For ventilation of the grain, you will find GMT and NR fans.