The Swampless Cooler

A very low power (P.O.C. is less than 10W) cooler that delivers cool dry air, and is driven by evaporation of water.

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Not your typical evaporative cooler, this design sends the humidity out with the heat! Leveraging what I believe is a common misunderstanding in how evaporative coolers work, I've come up with a way to keep the cooled air dry, and the power input low (about an amp of 12V DC for my current builds).

Basically this is just an aluminum plate with fins, glued into the bottom of a sealed cardboard box. A water tray is also glued in, next to the plate. Paper towels lay across the plate, and drape into the water tray, wicking water up onto the top of the plate. The fans in the box lid blow air directly on the paper towels, evaporating the water and sucking heat out of the plate, and the humid air is exhausted out the side of the box. A third fan is placed under the box (propped against the bricks in the pics), and blows air from the room across the fins which are protruding out the bottom of the box, cooling the air.

To see first hand how this works, grab a can of your favorite beverage that is at room temperature or above. Wrap the can in a paper towel, and get the whole thing wet. Place the can and wet paper towel in front of a fan, and check the temperature of your beverage when the paper towel is almost dry.

  • A New Proof Of Concept

    Dustin07/29/2021 at 22:36 0 comments

    Wow, time sure flies, no fun required... When I put this project up last year I had intended to get right to adding updates with more explanation, better pictures, etc. Thanks to what I believe was long covid-19, followed immediately by having to evacuate from the oncoming creek fire (for those that don't know, the biggest single fire in California of 2020) which was stopped a couple miles away from here, and quite a few other difficulties since then, it's taken a while... In spite of all that, there's finally an update!

    An explanation of the concept and how it differs from typical evaporative coolers is on my website here As far as I can tell, the idea is similar to an old fashioned cooling tower, but the concept is largely misunderstood and unexploited. I was able to find a patent, from a Korean inventor if I recall correctly, for a similar process. I don't remember what device I saved that info to though, so I'll post it in another update when I can locate it again (do note how long this update took, it may be a bit).

    So this is the new P.O.C. made from rubbing alcohol bottles, some scrap square(ish) tubing, pot scrubbers, two fans (1 blower using 2W, and a pc fan using 2.2W), and a small water pump (using 4.8W).

    There are three alcohol bottles, for the sake of description lets call them like this: There's a bottle that makes the corner, this bottle has the tubes running through it. There is another bottle taped to the front, this bottle encloses the ends of the tubes at one end so air can be pulled through them. There is also a bottle taped to the top of the corner bottle, to which the blower fan and monster exhaust tube are attached. The top bottle is basically just for mounting and ducting (there's also part of a hydrogen peroxide bottle used here for a mounting bracket of a sort). All the magic happens in the corner bottle. Packed around the tubing are (cheap stainless?) pot scrubbers I picked up at the dollar store (not ideal, they started to rust in days, but after more than a week of heavy use, they're holding up okay). Water is pumped over the top of the scrubbers and tubing, while air is pulled in from the bottom and exhausted out the top (note the humidity leaving with the exhaust). This cools the tubes, and air drawn through the tubes is cooled while still being kept dry.

    Now if you know something about evaporative coolers, and this looks like an inconsequential design tweak, I'd highly recommend reading the explanation of this cooling process on my website. That little design tweak is VERY consequential, it's not just a simplified two-stage cooler meant to keep the air dry. While the pot scrubbers are less than ideal, the fact that I'm using metal ribbons instead of the typical wood ribbons of a typical swamp cooler, also has purpose (though I'm not sure how consequential this choice is...still testing).

    I have little time/ability to thoroughly test the output, but initial testing shows some impressive numbers. First let's address the output air temperature. The front bottle leaks a lot of heat, compounded by the fact that the fan is putting suction on the front bottle apparently leaking outside air in from somewhere. Because of these things, the output air doesn't get as cold as it should, it's being re-warmed as it exits the cooler....ugh prototypes..... That little problem, combined with the fact that I don't have a thermometer that I can measure the output air with (the one I have is far too big physically to put in the right spot), means I don't know the actual output air temp. The output air sure does feel nice compared to the environment its in. That little wisp of cool air is practically arctic chill compared to the 110-115 I've been dealing with. As an alternative, I've used my cheap Harbor Freight infrared thermometer to get temperatures for different points on the cooler, as well as the bricks under the cooler tray. The bricks were measured through...

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