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Solar Cooler in a Can

Solar Cooler in a Can

It's been getting really hot up in the Northern Hemisphere lately, so here's a way to combat the heat by making a cooler that stays cool. Just add water!

This project is based on the recent invention of Emily Cummins, originally designed for impoverished families in Africa to keep meat and milk from going bad. The beauty of the cooler is its simplicity. It can be made from scrap materials that can be found in almost any home, sometimes in the trash. The Evaporation Fridge consists of an inner and outer tube, with a wet material in between the two layers. Perishable items are kept in the inner tube in a sealed container. As the water in the wet material evaporates, it removes heat from the inner tube and lowers the temperature. The whole process can be compared to the human perspiration system. Think of the fridge as a cooler that sweats, except less gross.


UPDATE: Check out the new version here:
http://www.instructables.com/id/Dew-Bucket-Evaporative-Drink-Cooler/
 
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Step 1Tools and Materials

Tools and Materials

I found all of my materials in my garage. If you can't find something, feel free to substitute similar object. My materials are as follows:

1 empty paint bucket
1 empty lantern propane tank(small)
2 plastic tank caps(from full or empty propane tanks)
4-6 rags/washcloths(anything that holds water: sand, sponge, wool, ShamWOW)
2 mesh gutter covers
1 can of spray paint
sandpaper
steel wool

The tools that I used are also very common:
drill press
1" hole saw drill bit
small drill bit
hacksaw with blade for metal
tin snips
hot glue gun


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107 comments
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Aug 19, 2010. 7:16 PMSabata says:
Coleman made a plastic bit called the Green Key that they included with their propane cylinders. Once the tank was "empty" you inserted the Green Key into the cylinder's valve. This allowed the last of the propane to slowly escape out of the cylinder so it was safe to recycle.

I just checked Coleman's site and it says that the idea didn't catch on so they aren't including the Green Key with their cylinders anymore. That doesn't mean a person couldn't locate one or two if they wanted to try this project without fear of fire/explosion.

Link: http://www.coleman.com/coleman/recycle/cylinder_dis.asp
Oct 25, 2011. 12:04 AMDIY-Guy says:
Sabata-
As an alternative method of "safeing" a propane can before cutting it, someone here at Instructables suggested filling it with water to displace and absorb any traces of gas. Maybe the author or someone else will recognize which -ible talks about using water to make an empty propane tank safe for cutting.
Jun 3, 2011. 11:40 AMAlpha2904 says:
I wouldn't say evaporator based coolers are new, for they have been around for sometime using wicker baskets and such.
Oct 24, 2011. 11:59 PMDIY-Guy says:
James R Patrick-
Yeah I'll say evaporative cooling has been around since Egyptian times, even thin sheets of ice were made at night using the method! (Sorry I have no URL reference for that factoid, but I did read it in a book many years ago.)

Nice -ible, keep going with these.   :)

DIY-Guy
Jul 11, 2011. 6:17 PMskitz says:
I'd like to share my experiences with evaporative coolers hoping someone may improve on this design.

http://www.instructables.com/id/Evaporative-Cooler-1/

I think it could spur some ideas with all the brilliant people on this site
Jul 6, 2011. 10:32 AMpohair says:
Does it need to be painted lack? You didn't say so...
Jul 6, 2011. 4:23 PMankitgarg2005 says:
boss here is mine
http://www.instructables.com/id/Portable-room-cooler/
Jul 30, 2010. 11:29 AMLectric Wizard says:
Nice instructable but wouldn't it be easier to use a coffee can or similar to make the food capsule ? Then you wouldn't have the possibility of your food tasting like propane odorant . It is a great idea though !!
Feb 25, 2011. 2:53 AMdanneauxs says:
yes, i was thinking this while reading. Great inst. & I think I'll try it with a coffee can. I always by metal ones just to keep for storage.
Jul 30, 2010. 10:34 AMchuckr44 says:
I've been seeing this concept for 10+ years but no web site ever provides hard info on how well it works. Like, if it's the ambient (air) temperature is 90F, how cool is the inside of the pot? Does it cool more in shade or sun? Inquiring minds want to know. If it's 90F in the outside sun, and the inside of the pot is 80F, 80F is not conducive to food preservation.
Feb 20, 2011. 10:04 PMjeanicrowe says:
I'm sorry I can't give you the hard facts that you want, but as you probably already suspect, there are a lot of variables. Yes, it definitely works better in the shade. The cooling varies with the materials used for both the inner and outer containers and what you use for the packing material. This idea has been around since the 1800's at least, probably longer. My Grandma used a big crock that she kept filled with lemonade or water for the field hands. She kept it in the barn and the heat caused the crock to sweat which pulled the heat from the liquid inside the jar. It was quite a bit colder than the outside temperature, but if it was 100 degrees out, the liquid could not be called cold. Whatever you put inside the container should already be cold for the best results.
A filling of damp sand or crushed charcoal works very well for a filling between the two containers. You could also use sawdust, moss, straw or leaves, as long as you have water to dampen them. Using a porous container for the outer layer increases the cooling (for example a large unglazed flower pot) or sink your container into the ground with pebbles around it and keep them damp. In the old days, people often dug out a hole and put a wooden keg into the ground with a wooden box sitting on top. They back filled around the keg with small stones, wet them down and filled in around the barrel with dirt, which was mounded up around the box to allow rain to run away from the keg. The box was the 'lid' of this under ground cooler. A stick was fastened to the box and containers of food were tied to the stick and hung in the keg below. This kept food from spoiling for several days.
Just a little note of interest: In the middle east they made ice by pouring water in shallow trays and placing them where the wind would blow over them. The water would develop a thin layer of ice which would be collected before sunup and stored in tall jars, kept in a cool corner. Their houses were cooled naturally by woven mats hung across the small windows on the windward side of the house. These mats were kept damp by ladeling water across them. Natural swamp coolers!
Jul 30, 2010. 2:52 PMironsmiter says:
This is a variation of a Zeer pot. when working at optimum efficiency, 80 degree dry day, you may get 60F inside the cooler. never tried it at 90, but should still work there. The design is not so much to refrigerate, as to cool. As for sun vs shade, it doesn't matter much, but the sun will add heat to the whole setup, so shade is better. What makes a bigger difference is local humidity. In the desert, these things work GREAT. In a rain forest, it wouldn't work at all. All depends on how well water is evaporating in your exact location. To that end, wind helps. I've used the clay pot/sand version, and was able to keep lunch meat edible for several days during the summer. Without the cooler, it would have lasted several HOURS. For me though, this style cooler works best to take HOT water, and give you COOL drinking water. You can fill the interior container with half your water, dump the other half onto the sponge/towel pad, and in an hour or two, have cool drinking water. To do this tho9ugh, I'd advise a stainless steel inner container. Used propane tanks tend toward not being food safe.
Jul 30, 2010. 1:12 PMgossumx says:
...bump
Oct 26, 2010. 4:44 PMtylerpienta says:
make shur u clean out the inside bc there would be gas residue and u put food in ther soo yea....
Sep 16, 2010. 8:14 AMoldhacker says:
Great idea. I am looking into adapting this concept to make a portable cooler for keeping perishable foods in while camping. Basically using evaporation cooling to enhance a traditional cooler / icebox. Does anyone have any thoughts on materials? For eample is the outer shell best made of metal (ie a good onductor) or plastic? Also, could it be finned to increase surface area?

Then the inner liner. If the food is put in chilled plus some ice blocks would it be best to use an insulated inner to keep the heat out or would that be counterproductive in that colling would not be efficient?
Jul 30, 2010. 2:50 PMDoc Holliday says:
I had a '57 MGA Roadster, while in Virginia in 1969-1972. I used to take ladies on tours/picnics, with a straw hamper lashed to the back deck. In front of this was a bottle or two of wine, wrapped in whetted towels. The airflow over these ensured a nice chilled beverage at the end of a drive in 90 degree plus weather. Despite the humidity, the car speed solved that.
Jul 31, 2010. 2:00 AMnutsandbolts_64 says:
I think I read something like this somewhere else... but as I remember it, yeah it works like that
Jul 31, 2010. 2:06 AMnutsandbolts_64 says:
Oh, and one more thing. IT'S PERFECT I TELL YOU, PERFECT!!!!! lol. I'll make another version.
Jul 31, 2010. 7:43 AMCulturespy says:
It would be great if you would find out what the average internal temperature is and post it along with the humidity and temp where you tested it.

Aug 11, 2010. 8:31 AMeulaliaaaa! says:
If you look on the mini images, this step looks like Frankenstein!
Aug 11, 2010. 8:25 AMeulaliaaaa! says:
Ingenious!
Jul 30, 2010. 6:17 PM--= Excogitate =-- says:
I think it would be awesome if someone (or perhaps myself) made a wind powered fridge with a similar principle. Have a wind turbine that is hooked to a gear box with a faster spinning fan. the fast fan blows air past the cooler which speeds up the evaporation process. No electronics!
Aug 1, 2010. 11:14 AMCabbages and Kings says:
Use a fan to power a fan? You are going to lose a lot of power unless you have a really high quality gearbox. Just have a funnel or a couple of bits of board to catch the wind and concentrate it on the cooler.
Aug 1, 2010. 3:57 PM--= Excogitate =-- says:
Lol, that would be simpler for sure. I still think I could make one. I've got a small planetary gearbox from a busted power drill. Or you could use bike gears and chain. And the turbine would be larger. It would catch more wind and generate more torque. I like the gear box because it exponentially increases the cooling of the air.
Aug 2, 2010. 1:32 AMCabbages and Kings says:
If you go to that much trouble why not build a compressor and get some really powerful cooling - ice even?
Aug 10, 2010. 5:04 PM--= Excogitate =-- says:
I dunno. A purely mechanical compressor? I'd be down for that. Don't know how powerful it would be just running off the wind.
Aug 8, 2010. 9:04 AMspartancaver says:
If you want to do this, try to find a local company that sells Liquefied Propane (LP) gas in bulk. i.e. a home propane dealer. Like Hank Hill who sells propane and propane accessories. These companies should have the old style propane tanks laying around gathering rust. Meaning the new tanks have Overfill Protection Device OPD's and are identified by the triangle valve. The old tanks have a star shaped valve knob. These can not be used unless retro - fitted with the OPD's. Since a new OPD cost about as much as a new tank; people will leave their old non-OPD tank and go buy a brand spanking new one. The propane dealers should be in the local yellow pages under LP dealers. Ask around if they have any abandoned old style tanks. I would not tell them what you are about to do with them and say you are going to convert them into a portable air tank. Like to carry compressed air for filling low tires out on your farm equipment and don't want to take the shop's air compressor all the way out there.
Aug 10, 2010. 7:42 AMbeehard44 says:
idea: Bar fridge evaporative cooler
Jul 30, 2010. 4:37 AMKiteman says:
I would seriously question Emily Cummins' claim to have invented this cooling system.

Evaporative cooling have been used in developing nations for some time - Cummins has only changed the materials, as the originals used two clay pots, with water-soaked sand in between. The water evaporated straight through the porous clay.

--------------------------------------

Having said that, this is a good Make. Well done.
Aug 10, 2010. 7:38 AMbeehard44 says:
Emily Cummins just adapted this idea from the ones made of porous clay more of an "upgrade" than an Invention
Aug 1, 2010. 7:29 PMRichardBronosky says:
Considering that a Nigerian man received an Invention of the Year award from Time Magazine for this very item in 2001 http://www.time.com/time/specials/packages/article/0,28804,1936165_1936254_1936632,00.html I'd have to call Emily a designer, not an inventer. Hers looks better, but Mohammed Bah Abba's can be produced for $0.20 and he has distrubuted more than 100,000 units! ( according to http://www.treehugger.com/files/2006/08/mohammed_bah_ab.php )
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Author:JamesRPatrick(Check out my blog!)
Currently pursuing a degree in Mechanical Engineering. contact: jamesrpatrick(at)yahoo.com