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Controlling air flow in recirculating mixed flow batch dryer with double bed mode

Oksanen, Timo
Computers and electronics in agriculture 2018 v.149 pp. 133-138
air, air flow, convection, dryers, drying, evaporation, farms, harvesting, vapors
Mixed flow dryers (MFD) are one type of devices used to dry grain after harvesting in farms. The moisture is removed from the grain by air convection through the grain bed using air ducts installed in the bed. In the normal mixed flow dryer, every other row of air ducts acts as inlets and every other row for exhaust. In this article, the double bed mode is proposed to be switched on during the batch drying process. By using the double bed mode, the air counter pressure increases by 69% and the travel distance of the air by 82%, based on computational fluid dynamics (CFD) simulations presented in this article. Hence, both the distance air travels in the grain bed is increased and due to the higher counter pressure the air flow rate decreases, allowing the better evaporation of water from the grain to the air transporting the vapor off.