A few years ago my family and I ran a shop in Ganmain, a fairly hot part of country NSW.
To add to the heat we had huge west facing windows and we were the main source of Takeaway Food ie: Pizza's, Fish and Chips, Burgers etc. Very nice too.
We couldn't afford the $5000+ we were quoted to Air condition the shop so I built my own.
It in no way compared to a commercial unit but it did provide us and our customers a little bit of welcome relief from the heat.
The following is a "blow by blow" of how I did it but I have no photo's of the actual unit so you'll have to use your imagination a bit.
A word of warning.
240 volts and water are a lethal combination.
When mixing the two please take all precautions including ensuring that you have fast circuit breakers installed. It might save your life.
Step 1: The Big Box.
A big box with bits in it and side panels with big onion bags full of wood shavings held on with wire mesh.
OK, they might have perforated troughs running along the top but so what.
My aim was to copy the theory as of delivering water to pads where it could evaporate and I could suck air through it and deliver it to a specific place as cheaply as possible.
The materials I used were:
4 red bread crates. 720mm X 600mm.
4 550mm x 670mm sheets of Rock wool.
4 550mm x 670mm pieces of mesh.
1 childs paddling pool. 1450mm x 1450mm x 200mm.
5 meters (almost) of 1/2" poly irrigation pipe.
4 1/2" poly elbows.
2 1/2" poly tees.
4 1/2" poly end plugs.
16 180deg radius micro sprays.
1 240v "Air curtain" fan. (Recycled from the shop doorway)
2 small 240v Aquarium pumps (unsure of the size but one big one would have been better.
1 sheet of 2mm(?) aluminium sheet (recycled).
2 180mm Air vents.
6 meters of 180mm insulated ducting.
Sundry wire, tape, bandaids etc
The tools I used were:
I have no idea of the cost but it wasn't very much.
Step 2: Making the "Unit".
4 bread crates were prepared for assembly by pre-drilling 1/4" holes in the base adjacent to all corners.
Using tie wire they were then wired together on their sides with bases facing the center forming a square with open top and bottom.
The top edge then had about 10 holes drilled in each crate (to attach the poly pipe later).
The sheet of aluminium was then prepared by having a hole cut in the center.
One of the air vents was attached over the hole and drilled and screwed in place.
I mounted the Air curtain fan to the air vent and attached the length of flexible ducting to the fans air outlet.
The ducting was then run into the shop via a floor vent and was strung up to the ceiling with the end placed above the cooking and service area.
The other vent was attached to the end of the ducting and secured.
Step 3: The Pool.
It looked absolutely nothing like the one in the picture but you get the idea.
Step 4: The Pump and Piping.
The 4 720mm pieces were then wired along the top edge of the unit and joined at the corners with the 4 1/2" poly elbows.
I then cut 1/2" of pipe out of 1 side and fitted a tee piece.
A 700mm length of poly pipe was attached to that and the water pump was hooked up to the other end.
4 small holes were drilled along the bottom of each 720mm length of pipe and a micro sprayer placed in each facing inwards.
Each sprayer delivered water to more than 1/4 of the top of the rock wool.
Step 5: The Evaporator Pads.
This proved less effective than I had hoped as the water doesn't soak into the rock wool, it just runs off.
I'd recommend buying a set of commercial pad inserts if you don't have a ready supply of big onion bags and wood shavings. If you do have access to those materials you'll save a fair bit if you make your own.
The pads were tied to the base (the inside of the crate) and held in place with a 550mm x 670mm piece of mesh.
Step 6: Test Run.
The fan worked well and delivered a fairly good stream of air into the shop but the pump wasn't able to deliver enough water to wet the pads properly.
Another pump was bought and the poly pipe cut on the opposite side of the unit to the first pump, a tee put in and the second pump connected via another 700mm poly pipe.
The poly was cut in the centre of the other 2 sides and the ends plugged.
This effectively cut the load on each pump to 8 micro sprayers.
The unit was then put into service and the pool filled via a hose as required.
It wasn't a world beater by any means and there is plenty of scope for improvement.
Couple these ideas with the 12v conversion of a commercial unit found here 12 Volt Conversion and you might end up with a top unit.