I did another post about building a simple playa air conditioner. I made several major innovations over existing designs, but also repeated a major failure of existing designs. In this post, I will describe my process of addressing this failure and improving further on the prevailing designs for DIY playa air conditioners.
Fundamentals
All DIY playa swamp/bucket air conditioners work on the same principle called evaporative cooling. The basic concept is simple; you force liquid water to evaporate into dry air. This turns hot, dry air into cool, humid air.
All the designs that I’ve seen use evaporative pads. Water is pumped over the pads, saturating them. Then a fan pulls air through the pad, evaporating the water in the pad. The cold air coming through the fan is ducted into a tent or yurt.
The Problem
Mots of these designs, including the apparent original, share a common flaw; they expose only a few inches of the pad to the outside air. These designs typically feature a bucket with a few small holes at the top to let air in through the pad.
The first problem is that the pad is designed to work across its entire surface area, and exposing just a few square inches of it to the outside air means the pad is not really working as well as it could.
The second problem; the holes are at the top because the bucket is full of water. So even if the pad was fully exposed to the outside air, most of it would be under water.
My First Design
My earlier post featured chicken wire which holds the pad away from the edge of the bucket. This means that the air from outside is able to reach the entire surface area of the pad.
The problem with this design is that the bucket is still full of water. So even though the pad is fully exposed to the outside air, most of the pad is under water.
Version Two!
Here are the two buckets with their lids side by side. The top bucket is the evaporative chamber. The bottom bucket is the water reservoir. Cutting through these is easy with a simple box cutter.
As you can see, the first bucket has drain holes which lead down into the reservoir. The evaporative pad sits in a column under the duct, drawing in hot, dry air from all directions.
Here is the evaporative pad, surrounded with chicken wire and with two drip lines installed. These are just sections of tubing with their ends crimped with zip ties, and holes punched every inch or so with a hot soldering iron.
When the evaporative column is inserted into the top bucket, the lines run down into the reservoir bucket like so.
I replaced my previous pump design with this one which is more clean and probably more reliable. These pumps have barrel jacks which run through a splitter and then to a power supply. Also, these are beefier pumps because the USB-powered ones could not lift water up high enough for this design.
I also found a beefier 200 CFM fan which can run into the same power supply. I added one duct adapter to each side, and attached an eight foot section of 4-inch dryer duct. This will run into the tent. The other good thing about using barrel jack power is that I have several batteries which will be able to run this newly redesigned system.
The same dryer duct quick disconnect runs down into the evaporative column and connects to the fan and duct.
This design improves on all the problems identified with the previous design. Looking forward to a cool playa experience!