How to make a small compressed air generator?

[Archerite]

Voltage regulator…

Thanks! Off course that would be a but more accurate. The other things I got right then though...right?

If one actually had a need for compressed air, and you had containers you could store it in that didn't rust out, and the space to store them, filling tanks with excess solar during the day would be useful.

All these ideas, while fun, really pound home how useful lifepo4 batteries are for their size/weight.

True. I would not have bought the compressor just for this experiment...but since I already have it now and see the possibilities I started to wonder. I have also read an article about CAES (Compressed Air Energy Storage) being actually used commercially somewhere in the US and Germany It think it was. (I'll link to it when I find the article again) But as said before efficiency is really low and it still relies on natural gas to heat the air before it get's to turbine. It's to get the water out of the air I believe.

For size, weight and capacity it's indeed not even a competition with lifepo4 batteries. But if you got the space for big huge air storage tanks...like you see in that video above...then it becomes a serious option to also use it for electricity. I am still learning about how air pressure works and all the measurement units involved so I am no expert by any means! It took me a few months to really get it for electricity when starting with solar...and I still consider myself a beginner in most cases. Maybe an advanced beginner though...

300 bar compressors are common because of PCP air guns (I have one)

That looks awesome and with such high pressure...if I get it right that is....in theory you have more air volume. right? And that stored in a much smaller container! Even with a few pressure regulators/converters to get it down to what pneumatic tools are designed for....it will still be much smaller than my current 14L portable air tank! Hahaha

Besides the high price tag of that compressor....it also makes a serious amount of noise it seems. Way more than my "regular" compressor I got now. But if the stored air volume is big enough that might not be a problem. Just fill it up during the day....and than use it in silence during the night! My biggest usage will be blowing dust of things and some air brushing....so that would be awesome to have a small tank like that.

For now though...the one I have is probably good enough. ?

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Small update on that is more on topic:
I really need to get a wind turbine / motor / generator that can give enough power at really low RPM's to keep the noise down a bit. The sound of airflow is not much of a problem....but when this generator makes more sound than the compressor itself...that would be too much right?
I am looking at getting a big 300W wind turbine generator from amazon...but it cost around 200 euro's. If it will work as I want it would be worth it...but I think I am going to experiment with some cheaper options first.

I have also seen that a stepper motor can be used as a generator, but it won't give many watts I believe. At least I could not find much info on it...most simple experiments only show voltage on a multimeter and some lights or LED's connected to it. That does not say anything without also knowing the maximum amps it can give at that voltage...and together how many watts it will generate. Guess the solar knowledge of electricity pay's off now, hahaha ?
Since I attempted to build a 3D printer from scratch a few years ago I have stepper motors in a box somewhere just laying around doing nothing! So can't hurt trying to see what kind of power they can generate! At first just hook up an electric drill or even a dremel like tool to get high RPM's to get the maximum power output capability! From what I have seen in the few youtube video's it should be about 8-12 volts per coil, but you can put them in series after rectifying the sort of AC output it generates. I am hoping to get anything between 18-24 volt's on the low rpm's I mentioned so a victron MPPT can lock on to it ( I know it's not built for it...but I have also seen people use them anyway for hydro installations)

Once I get to testing anything I'll post the results here. ?

 

[Archerite]

This might not be the right place to ask...,but I'll try anyways (sorry if not allowed)

I drained my air tanks today to let the water out and that orange portable one...which is brand new and less than a week old...had some nasty rusty water comming out of it! Is this normal? Should I be worried? Should I return it?

At the very least I am going to ask the question on the amazon page for the seller to respond to. hopefully.

I do have high temperature and humidity at the moment (26-30 celsius at 50-60%)

The compressor itsef is also new and just two weeks old, but that water came out clear. Deffinatly going to put in filters between everything now!

Thanks in advance for any advice.

 

[12VoltInstalls]

the inside of tanks are seldom coated

 

[Mannfamilywoodworks]

Hook up an impact gun to an alternator on a belt attached to a pulley.
Run wires from your alternator to a battery. Boom. There you have it.
Go to the junkyard now.
Old alternators on mk1-mk2 Volkswagens have an external voltage regulator. Brush type. Go get one of them Maybe. New brushes can be purchased and everything

 

[Mannfamilywoodworks]

This might not be the right place to ask...,but I'll try anyways (sorry if not allowed)

I drained my air tanks today to let the water out and that orange portable one...which is brand new and less than a week old...had some nasty rusty water comming out of it! Is this normal? Should I be worried? Should I return it?

At the very least I am going to ask the question on the amazon page for the seller to respond to. hopefully.

I do have high temperature and humidity at the moment (26-30 celsius at 50-60%)

The compressor itsef is also new and just two weeks old, but that water came out clear. Deffinatly going to put in filters between everything now!

Thanks in advance for any advice.

Pretty normal in tanks.
You do not want to use that air/water/rust
for airbrushing. You’ll ruin your gun.
Definitely put an in line filter and drain tank after uses like it sounds like you’re doing

 

[Archerite]

Pretty normal in tanks.
You do not want to use that air/water/rust
for airbrushing. You’ll ruin your gun.
Definitely put an in line filter and drain tank after uses like it sounds like you’re doing

Thanks. I have been doing some research on rust issue and it seems to be normal that the condensate takes the rust with it down to the bottom of the tank. I read about this already but thought it was only an issue with an older or heavily used tank/compressor. This one is supposed to be brand new...and it looks like it from the paint job and state of the gauges. they even had the protective plastic still on them.

If this is just normal then I guess I have to live with it, but I might want to change that drain valve on it. It's more like a screw at the bottom and it's impossible not to get rust water on my hands that way! I like the little handle drain style knob on the compressor itself way more! It's very low to the ground and at a weird angle...but at least it can be drained without having to touch whatever comes out.

While airbrushing is one of the main reasons for buying the compressor, I have so far only used it to blow out dust from holes through the wall. Putting in some conduit for ethernet, fiber and two 35mm2 DC battery cables to connect stuff about 5-6 meters apart in the other room. Blowing out the dust and debris worked great! I even made some "dust collection tents" to catch it at the other side and I think 95% of it all was captured inside!

The hardware store where I bought this mostly has stanley branded stuff and so only two types of filters but I am not really sure what the second one does. The first one is a water trap so that's pretty obvious on what it does right. But I might look into better filters online somewhere and filter out even more bad stuff before the air comes into the airbrush.

Would it make sense to put two of the same type filters in series before it enters the second air tank? Would that eliminate the water issue or is it just to reduce it? I am pretty new to compressed air

 

[12VoltInstalls]

It would make sense to put a drop tube with a drain in the bottom. A big diameter T with a 1” tube a few feet long will take out a lot of moisture and junk snd let the filters and water trap work optimally.

 

[Archerite]

It would make sense to put a drop tube with a drain in the bottom. A big diameter T with a 1” tube a few feet long will take out a lot of moisture and junk snd let the filters and water trap work optimally.

I'll be looking into modifying the water drains with a tube so I can catch the dirty water a little easier.

It seems I may have broken the srew valve on my receiver tank already...filling it up with air made it spit out more brown junk at the bottom. but the valve was screwed in all the way! Should have been closed! Thinking of either sending it back or just modify it with a better valve.

As for the air generator with a stepper motor...I think I'll have to drop that idea! Found a project of a hand cranked generator with 25:1 (or other way around?) gear box only producing 24 volts at 700mah!!! Yeah....if that's all it gives than its not worth the effort.

I know my 'compressed air generator' is going to be limited by the amount of air anyway...but I hope to at least get 30-50 watt's out of it! For as long as it can keep spinning that is off course.
More would be better but no idea if that's realistic.

I am now really considering getting a small wind turbine generator that should be able to give 300 watts at 48v with just 600 rpm! Thinking of 3D printing a big wheel with many air intake blades so it can catch a lot of the airstream. Than blow at it with airbrush like pressure (30 psi I think) and it should run for at least 3-5 minutes hopefully with my current compressor tank volume.
It's just that this generator costs 200 euro's and that is a bit much for a 'for fun' project to try out...right? Hahaha

Thanks, and I'll post again if I did go crazy and order it anyway.

 

[Hedges]

Compressed air, far higher pressure than wind. As it expands to atmospheric pressure that turns to velocity, which you want to make effective use of. I think that would be mostly lost unless nozzle near blades, like a turbo charger. One of those could be used, but you can estimate the air volume required by displacement. RPM and velocity would be high (not good for 3-D printed plastic.)

Here's an air powered vibrator:

GT-13 Industrial type Pneumatic compressed air power turbine wheel type vibrator | eBay

Turbine type pneumatic vibrator. 1 x GT-13 Pneumatic Industrial Turbine Vibrator. end plates enables the vibrator to be used in the food and pharmaceutical industries.The GT-turbine vibrators comply to current international noise regulations under factory test contitions.

www.ebay.com

For water, Pelton wheel velocity is 1/2 water velocity (water reverses direction and gives of second half of its velocity.)

There are other air motor types, some with a vane, allowing expansion of air to drive it without the velocity of free air. Probably what's inside air tools like drill or impact wrench. Smog pumps work this way, and have been used for a small supercharger. Might work for your air motor.

https://www.pinterest.com/pin/357754764156019610/

There are electric smog pumps. If that is a permanent magnet motor, might work as complete compressed air generator. Except I think they use a different design flexible vane.


When I've looked up performance of air compressors it seemed much energy was lost just in that step.

 

[12VoltInstalls]

I'll be looking into modifying the water drains with a tube so I can catch the dirty water a little easier

Nope. You install a tube off a T for the mainline on the compressed air outlet supply

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It seems I may have broken the srew valve on my receiver tank already...filling it up with air made it spit out more brown junk at the bottom. but the valve was screwed in all the way! Should have been closed! Thinking of either sending it back or just modify it with a better valve.

Most often these are petcock type valves and if you screwed it in all the way it is wide open

As for the air generator with 24 volts at 700mah!!! Yeah....if that's all it gives than its not worth the effort.

That’s probably realistic.
A self-built device or a mod off that design with an air nozzle and perhaps a turbine-cut fun like a pelton water generator as a hybrid of hedges post might work. But the effort to benefit ratio is wacky

I know my 'compressed air generator' is going to be limited by the amount of air anyway...but I hope to at least get 30-50 watt's out of it! For as long as it can keep spinning that is off course.
More would be better but no idea if that's realistic.

Hedges is the edumacated weight on this
My gut is for the dollars and time buy more panels and another 100Ah of storage

I am now really considering getting a small wind turbine generator that should be able to give 300 watts at 48v with just 600 rpm! Thinking of 3D printing a big wheel with many air intake blades so it can catch a lot of the airstream. Than blow at it with airbrush like pressure (30 psi I think) and it should run for at least 3-5 minutes hopefully with my current compressor tank volume.
It's just that this generator costs 200 euro's and that is a bit much for a 'for fun' project to try out...right?

It would be for me; I don’t have time to do what I need never mind speculative things with ponderous benefit.
But if you were going to do something with wind, a more constant millivolt wind turbine in your locale might be worthwhile; not a lot of power but will produce at lower speeds without your participation and low- to -no high wind concerns: look up Lynx Wind Power - maybe you can find a copy of the plans somewhere

 

[Shimmy]

Active Power used to make compressed air UPSs, generally called TCAS. The key to making it work is heating up the compressed air before it goes into the turbine. The turbine disc was only about 100mm diameter IIRC, and the system had a ~100kW power rating. I think the pressure vessel was about 100L and 300 bar, and good for a few seconds of ride through.

It's been a while, but I think one of the benefits of the system was that it provided some cooling for equipment until the HVAC system came back online.

 

[Archerite]

Most often these are petcock type valves and if you screwed it in all the way it is wide open

I suppose you are right, screwed it all the way out and now it holds are again! thanks! ? It does look a little weird that it sticks out now though...but if that's how it's supposed to be I am fine with it for now.

It would be for me; I don’t have time to do what I need never mind speculative things with ponderous benefit.
But if you were going to do something with wind, a more constant millivolt wind turbine in your locale might be worthwhile; not a lot of power but will produce at lower speeds without your participation and low- to -no high wind concerns: look up Lynx Wind Power - maybe you can find a copy of the plans somewhere

It should have been for me too....and while I don't have the time to actually complete it any time soon either, I did get that generator! ? The reason was simple at the time of ordering....my curiosity won and I just HAD to get it and try anyway! It's a problem, but it's also what got me into solar panels and related components actually

Hedges is the edumacated weight on this
My gut is for the dollars and time buy more panels and another 100Ah of storage

Not sure about the first sentence here....but your right about the second one. That would have been the better deal...but this seems more fun.

That’s probably realistic.
A self-built device or a mod off that design with an air nozzle and perhaps a turbine-cut fun like a pelton water generator as a hybrid of hedges post might work. But the effort to benefit ratio is wacky

I have looked at water generators and pelton wheels and was fascinated how it all works. If I might get anywhere I do need some kind of nozzle to restrict and focus the air into the blades of the fan...whichever type that might end up to be. I have been testing this generator by spinning the "hub" with a cordless drill....and it does get up in the 48-50 volts at high speeds so at least that part of it is good.
I know a victron MPPT is not meant for wind turbine's but I have seen people use them with rectifiers..so I ordered mine with a rectifier included. When connected the MPPT does see the voltage and tries to "lock on to it" for lack of a better word by drawing current. When it does that the torque needed to keep spinning is definitely much higher and it even made my drill bail out to protect itself! Still works, but I guess it's smart enough to sense that it's "locking up" or something. Hahaha

Either way making a compressed air generator that can handle this high amount of torque is a big challenge! The only possible "air motor" I know off that has a high torque is a Tesla Turbine! have been looking at a few video's of that and it looks awesome! But I might just try something anyway just to see how much is required to make it spin...and if it can keep spinning while delivering power. I also have a true compressed air die grinder...it consumes air like it's nothing but it also has a massive amount of torque and speed!
Maybe it can at least run a few seconds on my compressor to at least see if this wind turbine is capable of delivering it's advertised specs of 48V and 300W. i highly doubt it though .....but I did get about 63W at 38V for a brief moment. The connection between the hub/axle and my drill was really primitive since I have nothing that really fits it! Need to figure something out for that.

I will most likely have to design and 3D print some strong gears to keep it spinning fast enough to generate anything significant. But even if compressed air is not going to work for it....I have other plans for it where it might be useful. Some sort of manual bike pedal machine like generator...I know it can be bought on amazon but making it myself seems more fun.

 

[12VoltInstalls]

know a victron MPPT is not meant for wind turbine's but I have seen people use them with rectifiers..so I ordered mine with a rectifier included.

What are you doing to brake it?

 

[Archerite]

What are you doing to brake it?

If you mean to stop it spinning like crazy in the wind....then I don't. Since what I got is just the generator part of the wind turbine.


And I used something that barely fit in the "hub" (not sure what it's called) so I could spin it with my drill and see what voltage I could get. But when I am actually going to use it as a generator I will need some big gears on it to lower the torque and then try make it spin fast enough to get decent power out of it. It's just another project on my list...one of many.

It has three insanely short wires giving out three phases of AC voltage. With the rectifier that has 6 diodes inside it gives "normal" DC voltage + and _ and a voltage between 0-50+ depending on how fast it's spinning ofcourse. I don't have an amp meter right now (blew it up a few months ago) and my current multimeters are clamp-on amp meters....so I could not put them on there as a load. But the victron MPPT did pull out a max of 20-30 watts....I know for sure it can do more but the coupling between the hub and the drill makes that very hard! It's off balance...so at high RPM the whole thing vibrates like crazy! And since it's not mounted to anything....I was fighting to keep it place while also holding the drill and not letting the wires get pulled out of the rectifier! As I said....not an optimal coupling to the drill yet

What I plan on doing is make some sort of an adapter and then use an "isolated coupler" meant for 3D printers that has some rubber bits in it....hopefully that will absorb some of the vibrations and allow for higher RPM's. And maybe even run it with the air die grinder...since that thing packs a punch in torque and RPM. All this just to test this generator and decide if I keep it or send it back. Never had big issues returning stuff to amazon so far