Instructables
Hi, I am Sahas Chitlange , aging 14 , from India . Here's my new innovation on fridge from clay. Its very easy and cheap to build and very cheap. In india the cost is about  Rs. 300 only. The project's principle is based on evaporation. you can take this system for camping where you need a fridge to keep your cokes cool. The materials required for making this easy fridge are:
1) Clay pots
2) some sand
3) water

For the first time to get the cooling effect you need to wait for 10-12 hrs. The thing you need to remember is adding water after a day.
 
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Step 2: Adding sand

Add some sand in the base of the larger pot. You may close the pot holes. I did not.  You may also heat the sand strongly to kill the germs as in India you get the sand on roadsides!

Step 3: Insert the smaller pot

Picture of Insert the smaller pot
Now insert the smaller pot in the larger one. Take care you may get your hands jammed during this process. I got once, Very painfull...
Also see that you have some gap left on the sides , you need to add sand there later.

Step 4: Add sand to the sides

Picture of Add sand to the sides
Carefully add sand on the sides of the pot. Avoid spilling it into the smaller pot , its very difficult to get that stuff out once spilled in ! Also add some water after you add sand.

Step 5: Cover it

Picture of Cover it
You can make a cover out of old pots as i did or simply cover it with a damp cloth.
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snoopindaweb3 months ago

cOOl.! ~( : - } )=>=== ] Favorited. The vote don't seem to work.

Chitlange Sahas (author)  snoopindaweb3 months ago

Thanks.

coinegue3 months ago

Thank you Sahas for sharing that knowledge.
Great, this is very sustainable!
Once I saw a Berber fresh water keeper. It was made by metal, covered by fabric parts. The trick is to mantain it wet, adding water outside. The water evaporation gets it super fresh. And the guy who add it told it works really well with high temperatures. I also heard and read about this techniques used in the north of Africa.
I'm from Portugal. The old arabs left in our culture this ancient technique, made with clay, then straw, then some fabric parts covering all. I think the only inconvenient is the smell it gets after a while, needs to change all the cover.
I want to try this in the Azores, but there is very humid. I saw here that it might not work so well. I'm curious, but I believe that will be the same or better...
I like the design of yours, its very cool... The sand and how you configure inside is fantastic.

aebe9 months ago
Low tech is always good , even if it just sits in the back of your mind , waiting for a need. In areas of low humidity , you might find that ice (frost) is possible , just by using a northern exposure at night .
thanks.....for posting.......
i am from india......

jsolterbeck10 months ago
This is so cool thanks for posting! I will try it here in America! ;)
tekaka10 months ago
thanks Sahas, we have been working on this for a couple of years, next spring we will go for our tenth year without fridge here in hot andalucia. thanks for giving us, he world, this support in surviving. abrazo tkk
rkrishnan710 months ago
Great Instructable! Your instructions are brief but clear and illustrated well. You may want to add that the temperature difference that you get between the ambient outside and the inside of the pot depends a lot on the relative humidity in your region. The effectiveness is best in arid areas where the relative humidity is low. I recall that these worked well during the hot New Delhi summers, but were not too good during the Bombay monsoons :)
You are so totally right about every thing you have said.

This is good.

BUT - one of the things I have found is that while there my be periods of high humidity - ranging from most of the time to only part of the time, - in those areas of fluctuating "seasonal humidity" - these things are still really good for those portions of the year where the humidity is low to moderate.

Therefore the reasoning of "ALL or NOTHING" must be checked against the circumstances.

If I can get an excellent source of refrigeration for 9 months of the year and it fizzes out over the three months of monsoon season - then it would be advantageous to capitalise on the 9 + months of quality refrigeration and extended food keeping it provides.

In addition the nay sayers for the use in high humidity regions are neglecting several other factors.

1. Insulation value & thermal mass of the pots, sand, and water slow down the heat up of the interior during the day.
2. Radiation to the night sky can cool down the pots at night.
3. Some water does evaporate regardless of the high humidity. If it did not then people in Florida could not mop their floors, clean their counter tops, or use clothes lines to dry their clothes. The "experts" talking about dry bulb & wet bulb temperature and evaporation are confusing air conditioning with refrigeration. Air conditioning has to do with cooling massive amounts of air to provide human comfort which is much different from keeping a few pounds of food from over heating. Human comfort involves how the human "feels" and reacts with its environment. Things like chill factor (how fast the water/sweat evaporates off the human body) are involved here. Meat on the other hand does not feel chill factor, however, it can dehydrate or rot, which is what we are trying to prevent or slow down with the pot system.
I forgot to thank the author for exposing more people to the concept that everything does not have to be high tech or expensive to work.

I do not think that this will catch on here in the USA because it requires effort and conscious daily thought to work, it is not automatic or convenient. However, I do hope that they will remember it, because it could save their life, or at least make it more comfortable, in the event that there is ever a long term breakdown in energy &and/or food supply in their area. I'm sure that the preppers will pick up on it.
Sorry, I'm so forgetful.

A possible improvement might be to have 2 lids. One black, possibly made of metal, to help with night time radiation to the night sky. The other white/silvered (reflective) and insulated for daytime use. You would have to be very conscientious about changing both lids while it is dark outside.
gn0stik rkrishnan710 months ago
The terra cotta should do a pretty good job at absorbing most ambient moisture, just keep it out of the rain. As long as it is well sealed, and covered, it should be fine.
rimar200010 months ago
Excellent work! I certify that these simple water based coolers are surprisingly effective.
oakback rimar200010 months ago
Only if the humidity is low. I always get excited reading about these and "swamp coolers", but when it's hot in my area, it's always very humid as well. Evaporative cooling doesn't work here! (Florida)
actually it can work prpoerly if u do yr research. many of the native tribes in the florida belt did the same thing but with larger pots. there are many examples that remain intact even to this day.
Unless I understand it incorrectly, given the wet bulb temp of Houston average, Your fridge would not cool much lower than 77f on most days... I think the coolers you're talking about Astral, were the kind that were also buried near a river or other water source. The temperature of these pots could get down much lower, but out in the air (as this and any reasonable modern version in any regular subdivision would have to be) won't go much below the wet bulb temp.

So Oakback is correct. We do not use swamp coolers in the south because the humidity is so high. This reduces the evaporation rate, raising the wetbulb temp, reducing the efficiency of such a cooler
According to: TLA = TDB – ((TDB – TWB) x E)
Where:
TLA = Leaving Air Temp
TDB = Dry Bulb Temp
TWB = Wet Bulb Temp
E = Efficiency of the evaporative media.

Without the added heat sink of a subsurface flow, you just can't get low enough to do better than our AC's already does. In fact, as the AC reduces the temp in a humid environment, the air becomes more saturated as the relative humidity gets closer to 100%. This means the wetbulb and dry bulb temps are pretty much the same in a house using AC to reduce the temp in Houston or Florida when it's humid.

Yes, the natives used swamp coolers to keep food better, but their methods are impractical for most, and if you have an AC, not very useful.
(removed by author or community request)
Being that at no point in his comment here did astral_mage do that, I am at a loss as to what you believe your point is.
Feel free to quote where he does.
VadimS rimar200010 months ago
http://www.the-snowman.com/wetbulb2.html
These types of coolers will keep the inside at just above the wet bulb temperature.
If the part of the world you live in has low humidity it's perfect (swap coolers for home cooling work on the same principle).
thinkpadt3010 months ago
This is similar to a swamp cooler. I lived in Arizona, where the temperature would get to 112F occasionally in the summer. I remember one night when the low for the entire day occurred about 4:30 AM, and it got down to 100F! Anyway, we had only a roof-mounted swamp cooler, and the temperature inside the house never got above 80F. It was entirely adequate year-round, and very economical, especially compared to a traditional A/C.
tauhid10 months ago
This cooler was called “aka Zeer” (pot ini pot) created by Mohammad Bah Abba (Nigeria) in 1995 and awarded Rolex Laurante in 2000. This cooler has been used in Africa as important life saver by keeping foods for a longer shelf life (more than 24 hrs) by reducing the temperature down to 15 degrees Celcius.

http://en.wikipedia.org/wiki/Coolgardie_safe
http://www.scienceinafrica.co.za/2004/september/refrigeration.htm
tauhid10 months ago
More than ten years ago such a refrigerator reported helped many Africans to keep their food or vegetables for a longer shelf life. I'm not sure who did but such a food cooler designer had been awarded by international organization (WHO?).. About a year ago I proposed such a use in my facebook account for Indonesian remote populations who have no electricity.
Wroger-Wroger10 months ago
We need a standardised cooling table - no doubt they exist.

Relative humidity, temperature, and the capacity of an evaporative cooler - the internal temperature.

A fixed set of temperatures, with different humidity levels and the internal temperature of an evaporative cooler.....

Actually the subject has been researched to death 10 million times over - but it would be nice to be able to plot the graphs and sort it all out ones self.



Ilan Voyager10 months ago
Many thanks to the author for this very nice and well made instructable, It's good to remind that there are ancient and effective techniques for cooling. As some have already pointed it works only in hot and dry climates. In Spain the "botijos" for cooling the drinking water are common.
gingerely10 months ago
To make this work (chill) even faster, I would soak the pots in clean water beforehand. Then put them together with the dampened sand as you have done. Maybe even put the whole thing in something that will hold enough water to keep the pots moist.
Nice instructable!
Namaste!
primosanch10 months ago
Nicely done.
vincent752010 months ago
Great.
This is the basic cooling system by evaporation? And let me tell you, it works great !
The same idea has been use by putting large jars full of water in egyptian house where the could pass a stream of air that was cooled by passing between the jars and the refreshed ai cooled the house. The technique worked for centuries in Egypt and other countries in the region … 
In rural France (before the 40's I saw many butter jars that prevented butter from melting by covering the butter pot with a cover that that was designed to contain water that could evaporate.
You certainly will not get a chilling effect … but it will keep food and dairy stables at a reasonable temperature under strong heat.
The basic ot what on may call "pottery refrigeration" is to use non varnished pottery for you can soak the part you want to be evaporated first in the water (ie cover) Ideally no varnished pottery should be used at all because … the higher the evaporation rate the more efficient the system will be
sdartnut10 months ago
Thanks for sharing this. I think I have seen something smaller for keeping butter cool on hot days.
Your instructions were well presented.
Steamcrunk10 months ago
Neat instructables. So it will keep veggies like tomatoes and ginger, as well as yogurt cool?
Chitlange Sahas (author)  Steamcrunk10 months ago
Yes ofcourse! It will cool down everything (exept icecreams).
well done, I love it.
onemoroni110 months ago
This is a good instructable. Thank you for sharing.
jacobpv10 months ago
how long it will take to get the required low temperature???
BCWatson10 months ago
Very good instructions! Could you explain a little how this works.
devangs310 months ago
I use a similar one at home, it seems similar to a traditional arrangement in our locality. Still, its good work :)
nreed410 months ago
Could you use salt and water to lower the temperature even further?
diy_bloke nreed410 months ago
I am not sure if salt and water would make a difference. The principle here is evaporation and salt does not do anything for that, might even harm it.
The reason why salt-water combo can get cold is because salt lowers the freezing point so the water can get colder (below zero) before it turns to ice, but in itself it does not cool at all
Chitlange Sahas (author)  nreed410 months ago
Will try
diy_bloke10 months ago
Great Idea Chitlange
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