Zero-energy cool chamber
Spoilage of fresh fruits and vegetables is a serious problem in tropical countries. Cool storage can prolong the life of fresh produce, but refrigeration equipment is expensive to buy, expensive to run, and expensive to maintain. There is, however, a practical, low-cost alternative for on-farm fruit and vegetable storage which employs the cooling power of evaporation. Zero energy cool chambers stay 10- 15° C cooler than the outside temperature and maintain about 90 percent relative humidity. And they are easy to build out of locally available materials, such as brick, sand, bamboo, straw, and gunny bags.
Living and breathing
Fresh fruits and vegetables are alive. They breath and ripen even after harvest. Cool temperatures stew this process, allowing you to keep your fresh produce longer and avoid spoilage.
1 Select a raised site close to a source of water.
2 Make a floor with bricks.
3 Erect a double wall 70 cm high, leaving a cavity 7.5 cm wide between the two walls.
4 Drench the chamber with water.
5 Soak fine, river-bed sand with water.
6 Fill the cavity between the double wall with this wet sand.
7 Make a cover frame of bamboo, sirki, straw, or dry grass.
8 Build a thatched-roof shed over the chamber to shield the chamber from direct sun and rain.
- Keep the sand, bricks, and top cover of the chamber wet.
- Water twice daily, in the morning and evening. A drip system can be built with plastic pipes, microtubes connected to an overhead water source.
- Store your fruits and vegetables in perforated plastic crates. Do not use bamboo, wood, or fibreboard boxes because these will be damaged by moisture.
- Can be constructed by an unskilled person No mechanical or electrical energy is needed.
- Requires a significant capital investment
Shelf life of fruits and vegetables in zero- energy cool chamber
Build your chamber on a site where breezes blow.
Remove all produce before treating the chamber with insecticide or fungicide.
Cost of cool chamber
Contributor: Dr. S. K. Roy
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