Here's another one

Cupie · Guru

Here's another one

Possum3 · Guru

I would imagine that the release of air (piston exhaust) would create extreme temperature variations so piston/valve/cylinder componentry would need to be ceramic or similar - with a solar powered air compressor this unit would be a GN's dream come true.

Dougwe · Chief one feather

Solar powered Compressor. You might need to carry a generator as back up.

Who said 'generator' biggrin

Whenarewethere · Guru

Compressing air is very inefficient, I have 1.2kW capacity in the car which is quick for inflating tyres or blowing dust off the car. It generates masses of heat. Then you need to remove water from the air which is really only possible if the air is cooled before it is used.

Air has advantages, if an air motor stalls it doesn't heat up like an electric motor.

Grandad5 · Senior Member

I met a fellow last weekend who dabbles in building his own alternative energy cars in his garage as a hobby. He's converted two petrol cars to electric and is now working on an air powered one.

My mind went in all kinds of directions trying to figure out how he would get compressed air to move a piston up and down until he told me he had converted 4 wheel motors from an old Bobcat.
I never realised Bobcats are powered by oil being pumped into these rotary designed motors. So, what this guy was doing was changing the oil for compressed air.

It all sounded quite interesting. And, it was keeping his mind occupied.

Jim

T1 Terry · Guru

A screw compressor is far more efficient than the old piston compressors for smaller air volumes, but nothing beats a turbine for big volume air compression, it just needs multiple stages to get the high pressure.
A variable displacement compressor as used in modern auto air conditioning would make an interesting reverse engineered air motor, but the radial blade motors used in air tools driving through a planetary gearset that could have different components held and driven to create multiple drive ratios, the way an automatic transmission does, could produce some very interesting results.

An interesting alternative to the battery/electric vehicle, instead of electric recharging stations there would be huge air tanks holding the highly compressed air for a very fast tank fill. Liquefying the air the air could greatly increase the storage capacity and the energy echange required to gasify the liquid would make an excellent coolant as a work around for possums potential problem.
One thing to be considered, when air is dropped from a high pressure to a low pressure it actually draws in heat energy. Try pumping up a tyre to pop the bead, then holding the valve part way into the escaping air stream and watch what happens ..... you can often hear the ice forming and popping when the valve is removed and the only restriction is the valve seat itself. So, would the exhaust be hot or frozen?
Anyone into high performance supercharged engines that use the old Roots Blower with a hood on top? Is the hood hot or iced when the engine is shut down after a hard run?

T1 Terry

Jaahn · Guru

Hi smile

Bigger diesels are always started by air. Not an air starter motor like trucks have but using the air direct into the cylinders. They have a 'distribution' unit, driven by the camshaft which times the air injections to the down stroke. Use about 350PSI air tanks as I remember them. The point is the engine accelerates rapidly over a couple of strokes then you pull the lever and the fuel is injected and it goes instantly. They usually use the compression in the cylinders to pump up the air tanks before they shut the engine down. Two start air tanks for safety.

My thinking is that air motors are an inefficient way to make power from my experience. But perhaps there may be better designs these days. Usually air is used because it is clean and has only one supply hose and no return hose. Also the motors do not burn out like an electric tool but just stall and keep going after you unload them. Who knows ??

Jaahn

-- Edited by Jaahn on Sunday 8th of December 2019 03:00:07 PM

MapleHunter25 · Veteran Member

I suppose the economics could pan out, if you skip some of the boring health, safety and reliability stuff. I can see how rolling out compressor stations would be much easier than electric fast chargers in countries with limited infrastructure. But really, with the current generation of high efficiency electric motors and adequate lithium storage it seems like a solution looking for a problem for most of us.

landy · Guru

MapleHunter25 wrote:

I suppose the economics could pan out, if you skip some of the boring health, safety and reliability stuff. I can see how rolling out compressor stations would be much easier than electric fast chargers in countries with limited infrastructure. But really, with the current generation of high efficiency electric motors and adequate lithium storage it seems like a solution looking for a problem for most of us.

The compressor station is still going to take energy to drive the compressors. electricity , diesel etc so would there be any real saving.

Peter_n_Margaret · Guru

Some time in the relatively near future, we will have lots of solar generation. So much that there will be an excess during the day when the sun is shining, way more than we can use. During this time we will see that excess electrical energy used to create other forms of energy.
Pumped storage (Snowy 2, and many others) will be one of the first. Hydrogen generation will follow. Compressing air could easily fit into that mix, along with desalination plants and other things that we have not even thought of yet.
"Renewable energy" is just that. Use it or it will be wasted. There will be more tomorrow.
Cheers,
Peter

T1 Terry · Guru

Peter_n_Margaret wrote:
Some time in the relatively near future, we will have lots of solar generation. So much that there will be an excess during the day when the sun is shining, way more than we can use. During this time we will see that excess electrical energy used to create other forms of energy.
Pumped storage (Snowy 2, and many others) will be one of the first. Hydrogen generation will follow. Compressing air could easily fit into that mix, along with desalination plants and other things that we have not even thought of yet.
"Renewable energy" is just that. Use it or it will be wasted. There will be more tomorrow.
Cheers,
Peter

If only the govts can get their hands out of the pockets of the fossil fuel industry, we can have more big batteries throughout the grid and store the excess renewable energy for use when needed. The electric vehicle industry needs to get on with the 2 way flow of energy storage in the electric vehicle's battery as well to offer more grid stability rather than just being a short term load. Mum's taxi of the future will have enough power stored in the battery to power the house through the night or during a power outage, but it could also be there to absorb the peak load and avoid the outage completely. Can't do that with a tank full of compressed air ......

T1 Terry

Tony Bev · Guru

Back in the day, before drill rigs, were hydraulic powered

Their radial piston motors, were all pneumatic (air) powered

The one drawback was the inability of the engine piston rings, to stop the condensation of the compressed air, entering the oil
As a drill fitter, I would religiously change the (now milky), motor oil on a weekly basis, every 60 to 70 hours

The exhaust port was always iced, and occasionally you could see small pieces of ice, blowing out of the exhaust

Just like at night time, you can occasionally see glowing pieces of carbon, leaving the muffler of a diesel truck

I certainly hope that they do perfect the air engine, perhaps being an in-line, and not a radial engine, may be the key to making it work

We can only wait and watch

Valkie · Veteran Member

Our politicians could run a jet liner on the hot air they expell.

Dick0 · Guru

Dougwe wrote:
Solar powered Compressor. You might need to carry a generator as back up.

Who said 'generator'

And don't forget Doug, we only run our generators at 2:00am 'cos everyone is asleep!