Zeer Cooler
The world’s cheapest refrigerator runs completely without electricity. The zeer pot, or the pot-in-pot, is basically 2 large earthenware pots, one pot smaller than the other. The smaller pot is put inside the bigger pot, and the space in-between them is filled with sand. The sand is made wet with water (twice a day) and a wet towel is put on top of the 2 pots to keep warm air from entering the interior. As water in the sand evaporates, it carries heat away from the inner core, thus cooling the inner pot which can be filled with fresh fruit, vegetables or meat.
The zeer can keep tomatoes edible for 20 days, as opposed to 2, and meat will last up to 2 weeks. The zeer will keep water at about 15 degrees Celsius.
The key however, is a certain degree of aridness, for at a certain amount of humidity, the benefit of evaporative cooling disappears. Techniques which rely on water-based evaporation work great in the mountains and desert... and not at all in humid areas.
The pot-in-pot is one of several ingenious applications of cooling by evaporation. The city of Qena in Upper Egypt is renowned for its porous-clay cooling vessels. In Burkina Faso, the Jula people’s traditional jars are sometimes soaked in water before goods are stored in them, so that they stay cool by evaporation. In India, a rectangular enclosure of wet bricks is used to preserve foodstuffs from heat. Water seeps slowly through the porous bricks, evaporating from the surface and keeping the entire structure cool. An improved version uses double-brick walls with wet sand between them. Fruit and vegetables inside the chamber are maintained at temperatures below 20° C.
A similar low-tech way of keeping food cool is a tin box (6 or so cubic feet) covered with 2-3 wraps of burlap (old potato sacks). The box is filled with food and placed at the edge of a creek. The burlap surrounding the box is well-soaked. The end of the long piece of burlap that surround the box is placed in the creek so the box will be continually kept wet through capillary action. If the weather is extremely hot, every couple of hours, soak the burlap on the box with water. The evapouration of the water keeps the food good for several days.
The zeer can keep tomatoes edible for 20 days, as opposed to 2, and meat will last up to 2 weeks. The zeer will keep water at about 15 degrees Celsius.
The key however, is a certain degree of aridness, for at a certain amount of humidity, the benefit of evaporative cooling disappears. Techniques which rely on water-based evaporation work great in the mountains and desert... and not at all in humid areas.
The pot-in-pot is one of several ingenious applications of cooling by evaporation. The city of Qena in Upper Egypt is renowned for its porous-clay cooling vessels. In Burkina Faso, the Jula people’s traditional jars are sometimes soaked in water before goods are stored in them, so that they stay cool by evaporation. In India, a rectangular enclosure of wet bricks is used to preserve foodstuffs from heat. Water seeps slowly through the porous bricks, evaporating from the surface and keeping the entire structure cool. An improved version uses double-brick walls with wet sand between them. Fruit and vegetables inside the chamber are maintained at temperatures below 20° C.
A similar low-tech way of keeping food cool is a tin box (6 or so cubic feet) covered with 2-3 wraps of burlap (old potato sacks). The box is filled with food and placed at the edge of a creek. The burlap surrounding the box is well-soaked. The end of the long piece of burlap that surround the box is placed in the creek so the box will be continually kept wet through capillary action. If the weather is extremely hot, every couple of hours, soak the burlap on the box with water. The evapouration of the water keeps the food good for several days.
posted by Sleeplesserf at 12:26 AM
0 Comments:
Post a Comment
<< Home