Evaporative cooling
Practical Action
resulting draft draws cooler air into the cabinet situated below the chimney. The Bhartya cool
cabinet uses this principle to keep its contents cool. Wire mesh shelves and holes in the
bottom of the raised cabinet ensure the free movement of air passing over the stored food.
Static cooling chambers
The Indian Agricultural Research Institute has developed a cooling system that can be built in
any part of the country using locally available materials.
The basic structure of the cooling chamber can be built from bricks and river sand, with a
cover made from cane or other plant material and sacks or cloth. There must also be a nearby
source of water. Construction is fairly simple. First the floor is built from a single layer of
bricks, then a cavity wall is constructed of brick around the outer edge of the floor with a gap
of about 75mm (3") between the inner wall and outer wall. This cavity is then filled with
sand. About 400 bricks are needed to build a chamber of the size shown in Figure 3 which
has a capacity of about 100kg. A covering for the chamber is made with canes covered in
sacking all mounted in a bamboo frame. The whole structure should be protected from the
sun by making a roof to provide shade.
After construction the walls, floor, sand in the cavity and cover are thoroughly saturated with
water. Once the chamber is completely wet, a twice-daily sprinkling of water is enough to
maintain the moisture and temperature of the chamber. A simple automated drip watering
system can also be added as shown in Figure 3.
Double
brick wall
Trays of food
Raised water
tank
Cavity
filled
with
wet
sand
Drip hose
Figure 4: A static cooling system. Illustration: Practical Action / Neil Noble.
Naya cellar storage
Practical Action Nepal has been successful in transferring cooler technology, similar to the
Indian Agricultural Research Institute design, especially to rural areas. It is called the Naya
Cellar Storage and was originally designed by Dr. Gyan Shresthra from the Green Energy
Mission and Mr. Joshi. It is comparatively easy to adapt the design to the users’ requirements
and the construction is made from locally available materials. The results have been
encouraging for rural food processors who had little or no income and have been unable to
acquire costly refrigerators.
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