Pot-in-pot refrigerator

Tonkrugkühler, Clay pot cooler, Canari Frigo

Clay pot cooler - Canari Frigo - Tonkrugkühler

Gemüseverkäuferinnen mit Tonkrugkühler, Female vegetable sellers with clay pot cooler, vendeuses des légumes avec un canari frigo, Ouahigouya, Burkina Faso

Pot-in-pot refrigerator is an innovative cooling device that utilizes the principle of evaporation to preserve perishable goods, such as food and drink, in areas without access to electricity. This simple yet effective technology, also known as a zeer pot, consists of two clay pots, a larger one and a smaller one, with a layer of wet sand in between. The inner pot, which holds the items to be cooled, is covered with a wet cloth. As the water evaporates, it draws heat from the interior, significantly lowering the temperature inside the inner pot and thus preserving the perishable items.

History

The pot-in-pot refrigerator was invented by Mohammed Bah Abba, a teacher from Nigeria, in the 1990s. Abba's invention was aimed at helping the rural population of northern Nigeria, where electricity is scarce and the climate is hot and dry, to preserve their food for longer periods. This invention has since spread to other parts of the world, especially in areas without reliable access to electricity.

Design and Operation

The design of the pot-in-pot refrigerator is simple yet effective. It consists of two terracotta pots, one larger than the other. The space between the two pots is filled with fine, wet sand, and the inner pot is placed inside the larger one. The sand acts as a thermal insulator but also allows for evaporation. The top is covered with a wet cloth to enhance the cooling effect through evaporation. For optimal performance, the entire setup is placed in a dry, ventilated area. The evaporation of water requires heat, which is absorbed from the inner pot, thus lowering its temperature. The efficiency of cooling depends on the external temperature and humidity, with drier climates seeing a more significant temperature drop inside the pot.

Applications

The pot-in-pot refrigerator is primarily used to store perishable food items such as fruits, vegetables, and drinks, extending their freshness for days or even weeks longer than would be possible at ambient temperatures. This technology is particularly beneficial in rural and remote areas without access to electricity, helping to reduce food spoilage and improve food security. It has also been used to store medicines that require cooling.

Advantages

• Eco-Friendly: The pot-in-pot refrigerator is a sustainable solution that does not require electricity, reducing the carbon footprint associated with conventional refrigeration.
• Low Cost: It is inexpensive to make, using readily available materials, which makes it accessible to people in impoverished regions.
• Ease of Use: Its operation does not require technical knowledge, making it suitable for widespread adoption in rural communities.

Limitations

• Climate Dependent: Its effectiveness is reduced in high humidity environments, as the rate of evaporation—and thus cooling—is lower.
• Limited Cooling Capacity: While it can significantly reduce temperatures, it cannot achieve the low temperatures of electric refrigerators, limiting its use for certain perishable goods.

Impact

The invention of the pot-in-pot refrigerator has had a significant impact on communities in hot, arid regions without access to electricity. It has improved food safety and security by reducing spoilage, allowed small-scale farmers and vendors to store perishable goods for longer periods, and has even facilitated the storage of certain medicines in remote areas. Its simplicity and low cost have made it a valuable tool in the fight against food waste and in improving the livelihoods of some of the world's most vulnerable populations.