Half round air ducts (Drying of Onions and Potatoes in bulk) Cross-cut of aeration system with ventilation towers. Product in bulk. Top view of storage room. Top view of pressure chamber with hatch control. Pressure room with wall made of pine boards. Pressure room with wall made of plywood and vertical beams. Pressure wall made of plywood and horizontal beams. Angular cross-cut of air ducts and pressure chamber. Alongside cross-cut of product, air ducts and pressure chambers. Cross section with air ducts under product. Air outlet opening with half-round duct. Half-round ducts. Pressure room for half-round ducts. Half-round ducts in the storage room. Retaining wall. Use of retaining wall in practice. Outside retraining wall.