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Portable worksite air conditioner Answered

I want to build an evaporative cooler, that I can take with me to my job sites.

My tool brand is Makita, so I want to use a Makita leaf blower mounted to a portable cooler. What I think I need your help with is, the small liquid pump for drawing water out of the cooler and sending to a misting nozzle should be DC, so I can draw power from the Makita blower battery.

Suggestions are welcome,

Ralph

Discussions

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harthoppy

1 day ago

redneck air conditioner!

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Jack A Lopez

5 days ago

I was also going to suggest you give some thought to DC-to-DC or PWM power converter modules.

These kind of modules are useful, especially when you have a battery voltage needs to be lower; e.g. if the leaf blower battery is 24 volts, but you have to power an electric air compressor or pump designed for 12 volts.

Also these modules are useful when you want to adjust the speed of a DC electric motor, to some value less than full speed, and to be able to do that without wasting too much power.

Sensors and feedback might be helpful too.

In particular, a pressure sensor would be helpful, if you're going to be using compressed air. That is to say, it would good if there was some mechanism to sense the air pressure inside the sealed air+water reservoir, and command the air compressor to slow down, or shut off, for to keep the air pressure from getting too high, and possibly exploding the reservoir.

You know, the kind of garden sprayer with just a hand pump usually does not come with pressure sensor or gauge, because the user would get too tired with the hand pumping before coming close to putting too much air pressure in the reservoir. But with an electric air compressor... well, you know, it is just something to consider.

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Jack A Lopez

5 days ago

The part you call, "misting nozzle" requires water delivered at pressure.

There is some minimum pressure needed to make the water spray out as mist. At pressure less than that minimum value, water just sort of dribbles out. As a consequence of this, not just any small liquid pump will work.

Also it does not have to be a water pump. There are designs out there, which use compressed air, which is stored in the same container with the water.

As an example, you might have seen this one, US Patent 5967415,
https://patents.google.com/patent/US5967415A

It has its air pump built into the cap.

Similar contrivances are used for dispensing pesticides or herbicides. Again, each of these is basically a seal-able bottle, with a hand driven air pump built into one side.

There are also pumps made to put pressure on liquid directly.

Actually, these kind of pumps, the kind designed for pressure, have something in common with the kind made to compress air, specifically: gas tight seals. Also the part that actually moves the air, or liquid, is usually a piston inside a cylinder.

In contrast, for the kind of pumps that merely circulate liquid, without developing significant pressure, the part that moves the liquid, is just this spinning, fan-like thing, or paddle wheel, or impeller.

It is kind of easy to see the difference upon taking the pump apart.

Unfortunately, the people who sell pumps, usually want to show you pictures of the outside of the pump, in their advertising copy.

By the way, another way to move water into air, without going to the trouble of "aerosol-izing"

https://en.wikipedia.org/wiki/Aerosol

the water into tiny droplets, is to just blow air over some wet thing with a lot of surface area, like a wet towel.

There is probably a name for the same thing, used in professional swamp coolers and humidifiers. I think they call it a, "pad" which is kind of a boring, nondescript name, but I think that's what they usually call that part.

https://en.wikipedia.org/wiki/Evaporative_cooler

https://en.wikipedia.org/wiki/Humidifier

I am also seeing the words, "wick" and "membrane". I think I like that word, "wick" best.

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RJF

6 days ago

Check garden irrigation, watering, There are misters that plug into pvc pipe. Look up water pumps on amazon. There are small ones used for table fountains. Use table, fountain, pump as searches. RJF

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Downunder35m

6 days ago

You could just make a box with the blower on top.
Have a look how the coolers on house roofs are designed.
They use a pump to ensure the filter stuff is always wet and also to backflush dirt and dust out of it.
If you don't mind to replace the filters every season you could get away without a pump.

You can get large filter sheets for commercial oil fryers, the same are used by people making bio diesel to filter the oil.
These things have quite good capillary features and if placed with the bottom in water it does not take long for the water to creep up higher and higher.
Downside of course that it might be difficult to keep them wet if the blower is too powerful.
But youcould use a 12V water pump of the cheap kind (similar style like aquarium pumps) and a step down converter to connect to the blower batter or blower motor.
If the blower moves quite a lot of air then these thick bath towels are a good alternative for the filters.
You can wet them porperly and they hold a lot of moisture, so the pump only needs to get activated every now and then, depending on humity and temperatures.