Solar brushless DC Evaporative cooler.

[wineboyrider]

So I have about 3 evaporative coolers, which work extremely well in our climate and I want to build a swamp cooler that runs on dc and ultimately powered with some solar panels. I have seen some plans on the internet, but most use brushed motors..

[amberwolf]

Youve probably got a few spare hubmotors...so drill out a belt pulley for the 6-hole disc brake mount on one, then cut up an old bike frame for tubing/dropouts to weld up into the mounting bracket to put the hubmotor in place of the old AC motor, aligning the belt pulleys. The pulley will probably be a much larger size than the one used on the old motor, cuz the hubmotor will probably spin slower than the old motor, so less need to gear it down for the fan speed you want.

Or get more ambitious, and switch from belt to chain (more efficient), and use the sprockets and bike chain off the old bike frame to switch out from the pulley/belt. You just have to figure out the right gearing for the motors speed at the voltage itll be running at on your solar setup.


(Id considered something like this for my evap, back before the fire when I still had one, but never got around to it cuz i also wouldve had to build a new casing cuz it was rusted out anyway).


I dunno about the solar part; youd have to poke around all the solar threads for that stuff.

[wineboyrider]

Great idea AW. Chains would probably be more maintenance though.

[fechter]

And noisy.

I built one year ago using a brushed motor. It worked quite well. The brushes lasted longer than the other parts. I found a motor that was the right RPM to drive a fan directly. If you have a belt driven squirrel cage fan, then it should be fairly easy to find a good motor. I would replace the belt with a toothed timing belt though. Old school V-belts are pretty inefficient.

I found a little 12v water pump (also brushed). The whole setup drew about 2.5A at 12v. With a bigger panel, you could use a bigger motor and get more air.

I've seen some designs for multiple stage evaporative coolers before. With 3 stages, you can get the air close to the dew point.

[craneplaneguy]

They may have a brushless fan I seem to recall: http://www.backwoodssolar.com/

After 28 years off grid, now that I'm grid tied, I just buy a conventional air conditioner at a big box store and let 'er rip. I used to have a lot of the power tools in my shop running off of 24 and 36 VDC permenant magnet motors, back before large and efficient inveters. I'm spoiled now.

[amberwolf]

I've seen some designs for multiple stage evaporative coolers before. With 3 stages, you can get the air close to the dew point.

Theres also evap stages for a precooler to a regular AC unit, which can greatly increase the efficiency of that. These dont need their own motors, though, becuse the one for the regular AC unit would pull the air thru. (or it could be replaced with a larger blower if more airflow is needed). I need to build one of those for the house roof unit we have now (because it needs *something* to cool the air from the roof that gets sucked into it to do the cooling of hte exchanger coils. That air is something well over 130F at best in summer, at least when it starts up.

Id also like to add a shade over the whole roof, but I dont yet have a practical design I could build that would also survive storms with gusty high winds.

They may have a brushless fan I seem to recall

At least some regular A/C units use brushless motors in their fan systems now. IIRC our roof unit does; it has is own built-in controller. A friends from at least a decade ago did, too; we tried to fix the controller (since that was all that was wrong with the motor) but it was potted in a way we couldnt get into to test and fix stuff without more work than it was worth.

[amberwolf]

I found a motor that was the right RPM to drive a fan directly. If you have a belt driven squirrel cage fan, then it should be fairly easy to find a good motor.

Didnt occur to me till you said this, but I suppose it might also be possible to build a mount for the hubmotors axle that replaces the central spindle of the squirrel cage, and places the hubmotor at one side of the squirrel cage, centered in it with a mounting bracket or ring, so it drives the cage directly. Just arrange a nother bearing on the other end of the cage, if you have to remove the original, and then setup the voltage for the motor to be the right RPM for the fan.

Eliminates the belt or chain entirely, increases efficiency, and reduces noise.

If the motor is large compared to the side inlet of the cage, it might block some of the airflow.

[fechter]

Yes, I bet that would work nicely. You could block one end of the cage as long as the other end was open. Ideally you'd want the motor in the center so the cage can draw from both sides and the bearings in the hub motor could support the cage.