Some of you may have seen my first Solar Cooler in a Can instructable, and it worked well, but it was designed for chunks of meat and cheese. This version is designed to accept three 20oz bottles of soda or three 12oz cans. If you haven't heard about evaporative coolers, they use warm water and evaporation to cool a medium in a way similar to the human perspiration system. Apparently they were used in ancient times to cool water and other things.
I have no affiliation with Mountain Dew or its affiliates or Pepsi Co. or its affiliates.
Step 1: 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
2 rags/washcloths(anything that holds water: sand, sponge, wool, ShamWOW)
1 mesh gutter cover
1 can of Krylon Fusion Plastic spray paint (white)
27 small plastic zip ties
steel wool
painter's tape
The tools that I used are also very common:
drill press
1" hole saw drill bit
diagonal pliers/wire cutters
tin snips
scissors
Step 2: Prepare Your Bucket
I wanted my cooler to be portable, so I used a paint bucket with a convenient handle. A larger five gallon bucket would also work. I chose a plastic one because it won't rust. The first thing to do is remove all of the paint from the bucket. Just get the sludge out and rinse it off. Mine was latex so after it dried it just peeled off. If the bucket has rust on the rim, use some steel wool to scrub it off. Lastly, mark drilling points for 18 holes in a honeycomb pattern on the side of the can.
Step 3: Drill Your Bucket
Use the hole saw to drill the eighteen 1" holes in the wall of your bucket. Try to make them even and consistent. These will be the "pores" of the system, letting water evaporate from them.
Step 4: Paint!
Painting the bucket white will help it reflect light and keep it from heating up the bucket. Since my bucket is plastic, I used Krylon Fusion for Plastic. I picked up flat white but now I think gloss white would look the best. Make sure you mask the handle so it stays shiny.
Step 5: Make the Cages
There are three cages for the bucket that will each hold a 20oz bottle of soda. They will be arranged in the bucket as shown in the second picture. Start by wrapping a layer of mesh(gutter guard) around a soda bottle, and then securing it with zip ties. The bottle should be able to slide in and out. Cut off excess mesh and zip ties with tin snips and diagonal pliers.
Step 6: Make it Plush
Now the cages need an absorbent lining, I used some clean rags. Cut three to fit on the inside of the cages, with about an inch extra. Then secure the lining to the cages with more zip ties.
Step 7: Shove it All In
All of the pieces are now complete, they just need to be assembled. First put a layer of lining on the bottom of the bucket to cool the bottoms of the bottles. Then squeeze the three cages into the bucket, all at once. I had to squish them all together and then round them out with a bottle after they were inside. It'll be a tight fit.
Step 8: Finish
That's it! This Dew Bucket is ready for testing. Just jam three bottles into their slots and add water, warm water works fine. Evaporative coolers perform best in hot, windy environments with low humidity.
At moderate humidity and a light breeze, this bucket cooled 90*F water(room temperature) to 69*F in one hour. The lining was soaked in 90*F tap water.
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Has anyone tried this in high humidity areas?
Try filling the tin can directly with water and measure the effects again. Also remember to keep it in the shade and cover the tin can if possible.
Anyways i expected it to not be efficient; it was raining that day
To answer dataphool's question, yes, the Relative Humidity DOES inversely affect the cooling ability, and yes, evaporative systems do work better in dryer environments, BUT... it DOES COOL at all humidity levels.
Our humidity here ranges from about 70% to 95% most of the spring, summer and fall. As a child and before mechanical [Freon] A/C poor folks like us had NO cooling other than table fans and wet sheets. And it did cool us somewhat. The biggest problem was having to get up several times during the night to re-wet and wring out the sheet!!!!
Only rich folks, or at least the affluent, could afford whole-house air conditioning, and in those days even theirs WAS EVAPORATIVE!
A house would have a REDWOOD COOLING TOWER [about 4 feet by four feet square and about 5 or 6 feet tall]. At the bottom was a water reservoir about a foot deep, and at the top was a set of "spray" nozzles. A pump circulated the cool reservoir water into the house and through a "radiator" in the central heating air handler and returned the warmed water to the sprinkler heads at the top of the tower.
The falling water droplets evaporated some of the water thus cooling it. Depending on the relative humidity, the water in the reservoir would be 25 to 45 degrees cooler than the ambient air. They had a toilet float/fill valve to automatically maintain water level because a LOT of water was lost to evaporation.
EVEN on a 100 degree 90% humidity day, the house interior would be down around 68 to 70 degrees, and the reservoir water temp [before circulation in the house] would be like 54 to 57 degrees.
So, even in high humidity, some evaporative cooling DOES occur.
As proof of that I suggest that any doubters do a test: on a day of high humidity in your area; pour ambient temperature [NOT hot or cold] water on your forearm, and then hold the wetted area in front of a table fan. You WILL FEEL the evaporative cooling effect. And I assure you that this will occur even at high Relative Humidities.
Since we now know that evaprative cooling occurs, and even in high Relative Humidity, the only issue in effectively using it is to make the "chilling" tower system LARGE ENOUGH to transfer enough heat.
About 10 years back I made a small test cooling tower out of a 55 gallon plastic drum into which I cut dozens of vent openings, and on days of 90 degrees and 80 to 90% relative humidity, my reservoir water would run about 55-58 degrees.
Of course in that test set-up I was not adding any heat to the water by trying to cool the interior of a building. The amount of water in my system was about 10 gallons captured in the unlouvred bottom of the louvered barrel.
I never got around to up-sizing the test system and trying to cool my house interior, but I'm convinced that sized properly it would have worked.
On the other hand this small fan: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=259-1346-ND runs on 5V @ 160mA, which could be provided by a pretty dang small solar array. Not much airflow, but it should be able to help augment the evaporative cooling in still air conditions.
I notice on both of your coolers you use wire mesh to make cages to keep the rags in place. Is this necessary? Couldn't you just wrap a bottle in a rag, dunk it in water, and throw it in the bucket?
I've also read that the ancient greeks served their drinking water in porous earthenware so it would stay cool as long as it held water. I'm wondering if a clay planting pot would work.
"Couldn't you just wrap a bottle in a rag, dunk it in water, and throw it in the bucket?"- You could, and it would still work, but it wouldn't be as convenient to use and it would fall apart if moved too much.
"I'm wondering if a clay planting pot would work."- Yes, any unglazed pottery should work. Just be sure to plug the drainage holes that most flower pots have.
That counts me out *dang*