Bruce and Jean's
Teardrop Trailer
Swamp Cooler
8/31/05
After seeing the swamp
cooler that Larry Sorenson built for the Outback Teardrop,
I decided to build one too. I found the
Kar Cooler on the net and used it as guide for mine. I had a
couple of fans left over from the trailer build and I purchased a
360 GPH bilge pump from a marine store. I mocked up a demo
from a tupperware container to see how it would work:
My preliminary
conclusions:
-
360 gph is *way* too big of a pump. 50 gph would be more like it.
There's a Y bypass in the feed to the pads (its below water in the
picture), part of the pump intake is blocked and its still way too much
water. If I open the end of the tubes to the pads its about right. I
think a channel across the top of the pad with holes in it would leak
about the right amount of water. -
The pads need to be tight to the sides so there aren't any air
leaks or air will just flow around the pads in the path of least
resistance.
-
Its 76F here tonight and there isn't much cooling going on. I
need to try it when its hot outside. I can't tell much difference
between the air from the cooler and just fans running. I'll try it with
a thermometer tomorrow.
-
The whole setup is drawing less than 2 amps at 14.1v (battery is on the
charger).
-
The plastic bin that I got doesn't cut very well. It fractures easily.
-
There's no way I'd run this thing inside the trailer. The pads
leak. Not a lot, just enough to make a mess. I'll need to duct it into
the trailer somehow, probably a duct to the window for now.
-
200 CFM seems like its plenty of air. I'll make sure and switch the
fans separately.
Here's what I ended up with for the final model. I solved the flow
issue by using drip irrigators to water the pads. Each dripper flows at
1 GPH so the pads stay wet with a minimum amount of water. I kept
the baypass since the hoses leak at the joints if I took it out.
I think it helps the pump prime too. I used hardware cloth to hold the
pads in place as well as screen the inside of the fans (I kept sticking
my finger in them). The pump has a hard time priming and I have to
unscrew the connection at the pump to let it prime if the lines are
dry. Its fine if there's already water in it. I used a
dremel tool with a spiral cutting bit to cut the plastic to
prevent fractures.
I experimented with the number of pads. I filled the box up with pad
material and ran a dripper line over it. It didn't seem to cool the air
anymore but it did decrease the amount of air coming out. I settled on
just the two pads as shown.
The container I used is a file box from Office Depot. I probably should
have made the
pads smaller so it could hold more water but it will run at least 4
hours with the 1/2 gallon it holds now. I left out the
louvers since they didn't really do anything. I think the louvers were
supposed to help with leaks and this one doesn't
leak like the mockup did. I can stick it inside the trailer on a
pull out shelf. It fits nicely in the sink so I have a place to stow
it.
Does it work?
Well, cool air comes out of it and it cools the inside of the trailer
when I stick it inside. We'll see how well it works the next time we go
camping.
Version 2.1. I got another file box and moved the pads and fans around.
It works even better with both fans on the same side instead of one on
each end.
It works really well when you drop in some ice but it still works with
just water. I'm pretty happy with it. I can just stick it in the cabin
but it gets pretty muggy in there unless I turn on the cabin
ventilation fan to push some air out the window. That pushes my total
amperage up to 2.5A.
Here's what I ended up with for the final model. I solved the flow
issue by using drip irrigators to water the pads. Each dripper flows at
1 GPH so the pads stay wet with a minimum amount of water. I kept
the baypass since the hoses leak at the joints if I took it out.
I think it helps the pump prime too. I used hardware cloth to hold the
pads in place as well as screen the inside of the fans (I kept sticking
my finger in them). The pump has a hard time priming and I have to
unscrew the connection at the pump to let it prime if the lines are
dry. Its fine if there's already water in it. I used a
dremel tool with a spiral cutting bit to cut the plastic to
prevent fractures.
I experimented with the number of pads. I filled the box up with pad
material and ran a dripper line over it. It didn't seem to cool the air
anymore but it did decrease the amount of air coming out. I settled on
just the two pads as shown.
Version 2.1. I got another file box and moved the pads and fans around.
It works even better with both fans on the same side instead of one on
each end. 
It works really well when you drop in some ice but it still works with
just water. I'm pretty happy with it. I can just stick it in the cabin
but it gets pretty muggy in there unless I turn on the cabin
ventilation fan to push some air out the window. That pushes my total
amperage up to 2.5A.