Non electric field refridgerator
Posted 22 September 2009 - 06:25 AM
"This is Mohammed Bah Abba's Pot-in-pot invention. In northern Nigeria, where Mohammed is from, over 90% of the villages have no electricity. His invention, which he won a Rolex Award for (and $100,000), is a refrigerator than runs without electricity. Here's how it works. You take a smaller pot and put it inside a larger pot. Fill the space in between them with wet sand, and cover the top with a wet cloth. When the water evaporates, it pulls the heat out with it, making the inside cold. It's a natural, cheap, easy-to-make refrigerator."
Posted 22 September 2009 - 02:25 PM
Posted 22 September 2009 - 03:30 PM
I am sure wet sand is much more conductive than dry sand is. And I don't think it would be airy enough to allow any evaporation below the top few inches. Light-packed cloth with a water reservoir would seem to be more evaporative (and maybe be a better insulator).
Posted 22 September 2009 - 03:37 PM
Posted 22 September 2009 - 03:41 PM
Posted 22 September 2009 - 03:47 PM
Unless the only purpose of the sand is to wick water in which case it would be latent....
Posted 22 September 2009 - 03:51 PM
Posted 22 September 2009 - 04:29 PM
Might try and experiment a little and safe if I can do a little better with a sand pit or something next time it heats up a bunch.
Posted 22 September 2009 - 06:04 PM
Water skins are similar.
Canteens are also covered with cloth, which when moistened cools the contents.
Those refrigerators are a brilliant adaptation. It looks like the outside pot (maybe the inside too?) is unglazed, therefore porous. As water wicks through it and evaporates, the whole thing is cooled.
The sand in between inner and outer containers. acts a water reservoir and provides thermal mass to keep the temperature even.
The guy's brilliant for putting all this together. Engineering at its best. He certainly deserves the hundred grand, the recognition, and more.
Posted 24 September 2009 - 09:03 AM