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Non electric field refridgerator


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#1 junior1

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Posted 22 September 2009 - 06:25 AM

If you are ever in a situation where you don't have electricity or propane and need basic refrigeration, this can help.


"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."

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#2 Quadrupliplex

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Posted 22 September 2009 - 02:25 PM

WOW that's pretty cool. I'm gonna have to try this out if i can find some similar pots and test the temps.

#3 kcmoxtractor

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Posted 22 September 2009 - 02:42 PM

Nice!

#4 ShroomGuerilla

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Posted 22 September 2009 - 03:01 PM

dude deserves that award.

#5 brax

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Posted 22 September 2009 - 03:30 PM

So what does the wet sand do, wick water to the cloth for evaporation or allow evaporation within itself?

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).

#6 brax

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Posted 22 September 2009 - 03:37 PM

Now that I think about it, I suppose it probably has more to do with the specific heat, the wet sand probably stays cooler through the day...

#7 kcmoxtractor

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Posted 22 September 2009 - 03:41 PM

Has more to do with latent heat than specific heat. Specific heat is how much energy it takes to change a unit one degree. Latent heat is how much energy is gained or needed by changing state.

#8 brax

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Posted 22 September 2009 - 03:47 PM

Evaporation of the cloth would be latent heat. Utilizing the thermal mass of the sand would be specific heat.

Unless the only purpose of the sand is to wick water in which case it would be latent....

#9 kcmoxtractor

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Posted 22 September 2009 - 03:51 PM

Yeah the cooling would be derived from the latent heat, the specific heat would be balanced between the outside and inside energy exchange.

#10 brax

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Posted 22 September 2009 - 04:29 PM

I've set up a t-shirt around a carboy in a water reservoir for cooling beer in the summer time (more like a coolgardie safe) . Usually works good for about 5-10F which is enough for me.

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.

#11 bugs

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Posted 22 September 2009 - 06:04 PM

In the American Southwest, and probably elsewhere, unglazed ollas, earthenware pots, are used to store water and cool it by evaporation. (Thanks Louis L'Amour for your insights into traditional ways)

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.

#12 junior1

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Posted 24 September 2009 - 09:03 AM

Wonder if this can be used in hydro, like as a res chiller? :weedpoke:




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