ANNEX 4 - VENTILATED WET AIR SYSTEM FOR CHESTNUTS STORAGE

A. The farmers who can afford to make some modifications (Fig. 16)

1. use plastic or wooden boxes (20 kg);
2. make a double floor with a grid surface under a thin layer of which the water is running (pallets can be even used); water can flow in open channels or just over the ground (the first is better; in the latter case a slight slope is required to ensure that water flows forward);
3. place a fan over the main door to create a slight depression in the head space over the boxes.

Fig. 16: Simplified ventilated wet air storage system for chestnuts in sacks

A small window must be opened (50 cm2) above to the entrance of the water pipe to allow the air to flow over the water surface when the fan is working. A net must covered the holes to avoid the entrance of animals.

Precautions:

• chestnuts must be treated with water curing;
• water must be sanitised as told previously;
• boxes must be tightly stacked .

B. The farmers who can afford to modify completely the home storage facility (Fig. 17)

1. built up a wooden wall which touches tightly the walls, the floor, the ceiling, with a small door (1 m2 just for plenum check) in the middle, and openings on the bottom which are tightly connected with the pipes placed on the floor;
2. cover the floor with plastic film to avoid the contact of chestnuts with the ground;
3. place a fan (1) on the window of external wall (brick wall) which push the air from outside into the double wall (plenum) and from this to the pipes;
   

Fig. 17: Ventilated wet air storage system for chestnuts in bulks

4. place over the floor perforated metal or plastic pipe (perforations must be smaller than chestnuts); these pipes should be placed along the floor from one wall to the other; one end (the smallest one) of these pipes touches the wall tightly, while the other end is opened on a double wooden made wall;
5. place a water shower in the double wall, just in front of the fan, (one alternative is the use of wetted jute sack) to oblige air to pass through the water, in order to become humid and to cool down (in the case of shower system, water is collected on a metal tank on the ground which covers all the surface of the plenum, with 5-10 cm high walls and a discharge pipe; this pipe is closed when the fan is on while it is open when is the tank is full and the fun is off; this water collector is important because even when the shower is off, the air flows over the water surface, becoming humid and entering into the perforated pipes);
6. spread chestnuts over the pipes; since pipes are perforated, air flushes
   through chestnuts aspirated from another fan (2) which is placed on the opposite wall where the main door is located;
7. a window is needed on the brick wall, close to the fan which push the air into the plenum, to use when outside wind is strong to substitute the fan.
   

Characteristics for 20 m2 room with an height of 2.5 m:

n. of perforation on the pipe: 50/m2
Ø of hole: 1-1.5 cm
pipe sizes: wide 25 x high 20(wooden wall side) to wide 15 cm x high 10
(end side)
height of the chestnuts bulk: 70 cm
air speed flowing in the pipes: 6-8.5 m/s (0.2 L/kg-s)
air speed flowing out from the chestnuts bulk: 0.1-0.3 m/s
fans with speed regulator to provide 6.5-8 m/s

If chestnuts are loaded in perforated plastic or wooden boxes, perforated pipes are not used but the wooden wall is slotted and the boxes are placed tightly close to the wall so the humidified air from the plenum flow through the boxes.

Precautions:

• when main door for loading is on the brick wall in front to the double wall, the perforated pipes must be shorter to allow for opening of the door and so they must be closed with a lid;
• seal accurately the double wall with silicone and the doors with adhesive tape;
• chestnuts must be water cured;
• water must be added of chlorine (500 ppm );
• before starting the storage all the room must be sprayed with bleach solution or other bactericide.