For comment please:

A company in Australia has developed a compressed air rotary engine.

Go to http://www.engineair.com.au/ for a look.



There has been some talk about mating this engine with an electric engine with regen and plug-in recharging capability.

The rotary compressed air engine is incredibly small and efficient, with variable power output depending on PSI. Something like this has been done in Europe, except with a normal piston style engine, and is nowhere near as efficient.

The combination of the two would offer excellent FE (all electric) and range.

Yes...compressed air tanks are required and take about 3mins to refill.

Yes the batteries need recharging (with regen also) probably Lithium Ion.


However...this seems to have great potential with low/no pollution.


...and before anybody pipes up with "but how is the electricity generated"...we all know that pollution wise centralised power generation is far better than petrol diesel power generation!

Anyway...take a look at the web site.

Propeller heads please comment...

It is a problem of specific energy density, the energy available per unit of weight. The advantage of fuel engines is they only have to carry fuel, not both the fuel and oxidizer. But in a battery or compressed gas tank, all of the energy has to come from the consumables. The specific energy density directly ties to the vehicle range.

Now I have no bias for chemical, mechanical or other closed energy storage systems. But they all suffer from low specific energy densities and that limits their range. I'm not ready to sell my Prius.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Thanks Bob.

I'm no mechanical engineer but it sounded so good, so clean...if you get my drift.

Thanks.

It is a good idea if you have short range or working in enclosed spaces like warehouses and underground. Then there is the potentially tremendous accelleration. But another option would be to use it as part of a hybrid-pneumatic vehicle.

GM had proposed a hydraulic hybrid that used a nitrogen charged tank to hold the energy. Hydraulic motors have a terrific ability to handle high energy loads for regenerative braking. But the energy storage was the nitrogen gas charged tank.

That air motor could be used in a hybrid-pneumatic vehicle, avoiding the hydraulic fluid. The engine would only be run when the air supply was low and being computer controlled, it would operate in a high efficiency mode.

You Aussies are just about as bad as us about shade-tree engineering vehicles. It would be a fun project to replace the engine of a suitably sized car with the air motor and tanks. Then put a small engine in the trunk to keep the air tanks charged. Just for grins, put a heat exchanger on the radiator, exhaust and around the air compressor for the feed-air before running into the motors. From a thermal dynamic standpoint, it could be a very efficient system.

The goal should be to translate as much heat energy from the engine into work and the air feeding an air motor heated by otherwise waste heat would be very efficient.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

I like the idea of using something other than electrics for doing hybrid applications -- espeically mild hybrid applications -- as it won't suffer as much from shortages of battery chemicals, so it could probably be scaled to widescale production sooner.

That is an interesting idea. I still think if all the power is coming from the engine, it will be hard to beat a direct mechanical linkage to the wheels for long steady-state cruising -- like existing hybrids which use electrics for supplemental peak-power. However, this system, combined with some air tanks should do very well in an environment with lots of stop and go.

Another idea I just thought of for an gasoline-pneumatic hybrid would be to cool the air-tank with blowers similar to an air-conditioner, then dump the chilled air into the intake manifold on demand as a form of supercharging. (There would also need to be a one-way valve on the intake to keep this overpressured air from simply escaping) Lots of high-pressure, cold intake air with no backpressure on the engine could make for a strong boost in acceleration performance, and would allow the makers of the car to gain an efficiency advantage from downsizing the engine somewhat without losing peak horsepower. Pneumatic motors could also be used to start and stop the engine, and relieve accessory load from the drivetrain.

I knew the people who made "Mad Max" would catch my 'drift.'

WOOT! WOOT!

Bob Wilson

ps. The only thing I didn't like about "Mad Max" was they didn't spend enough time with the vehicle builders and inventors. <GRINS>

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

As I understand it, and after speaking to the inventor, there are some plans to put the air engine motors in paralell - all on the one drive shaft...along with the electric motor.

Putting range aside for just one moment, this would allow total engine power to be adjusted according to the size of the vehicle, with very little engineering changes. Just drop another compressed air engine in-line.

This is only possible because of the size (and power to weight ratio) of the CAE.

The electric motor would only receive energy from the batteries that were recharged at the end of the day. Regen braking would be achieved using the CAE to refill the tanks. I guess it would probably sound like trucks using engine braking.

The CAE's would be brought into play sequentially the harder you tried to accelerate. A small electric compressor would also be available for recharging the tanks when parked.

Engine power is directly proportional to PSI available.


The nice thing about this technology is that in the event of a serious accident, it would only be compressed air that escaped.

Surprisingly though, the estimated vehicle weight is lower than some hybrids, due mainly to the amazingly small size of the CAE. The air tanks are actually lighter than you would expect.

Even though I own a Honda Civic Hybrid-II myself, I am intersted in persuing this as a personal project. My vehicle of choice for this will probably be a Morris Mini Utility (pickup). Very small, with an east - west motor configuration.

Probably CAE only to start off with. Then I will slot in a printed circuit electric motor and batteries later.

I am also aware that somewhere else in Australia they have produced an hydraulic regen motor, that assists a standard ICE engine on take off only.

I think that they are doing a deal with the US Army (of course).


In reference to Mad Max. Trust me, outback Australia is pretty close to that now. Although we pay upwards of AU$1.40 a litre in the city, outback you can add another 0.50c to that.

Don't worry about locking the doors on your car, just remove the gas tank and take it with you!. Fun stuff.

I will keep you all up to date as the project proceeds.

You asked for propeller head comments.... At the end of and just after WWII, piston aircraft engine development was at its peak. One of the tricks used to increase power and lower fuel consumption was the Power Recovery Turbin (PRT). It is basically an air motor that uses exhaust gasses to run the motor and then is connected to the crankshaft through clutches to add power without extra fuel consumption. The PRT is simular to the "hot" side of a turbo charger but instead of using the prt power to make compressed air, the power is connected directly to the crankshaft. PRTs add about 10 to 20 % more power without added fuel consumption. Turbo chargers also add about the same amount of power, but because of the extra air they pump into the engine, they need to add extra fuel to get that extra air to burn. The Wright Turbo Compound R-3350 made good use of the PRT system producing up to 3800 HP out of a 3350 Cubic inch engine. The engines were used on several airplanes both civil and military, some of which can be seen still in use today. Some of the most common civil airplanes that used them were the Douglas DC-7 and Lockheed Super Constellation. If you watch the news about forest fires you will see Lockheed Neptuns. They are high wing airplanes with two piston engines and two jet engines, the piston engines are the Turbo Compound R-3350s.

Personally I think a piston engine with a PRT would be a better choice then an gas/electric hybrid. On my Insight the IMA adds only 10% to the power and is only working about 5% of the drive time and that includes regen. A PRT would work more or less all of the time and add about 10% or more to the engine power all the time. The best choice would be a Gas/Electric/PRT Hybrid.....Louis

Louis,

You know...just when you think you know everything about everything someone comes along that knows just that little bit more.

I mean this in a "kind and loving way" of course....no offence intended.

I turned 50 last year, and I'm lucky if I can remember how to turn my alarm off!

Very impressive stuff indeed.

I was always of the opinion that you never get something for nothing.

You know what I mean - "Why not nail a wind generator to the top of your car to generate power for the electric motor?" Well because it would slow the car down in the first place.

I would have thought that by putting a generator on the exhaust that this would impeed the free flow of gases, and therby reduce the power of the motor.

I guess it must work...well as you pointed out, it is in use now.


Thanks for your post nonetheless.

Aussie

The reason you don't know everything about everything is because you are such a young pup. I would expect that by the time you become a wise old man of 54 like me you will know everything. (just kidding)

As far as getting something for nothing. You might say that for all these years we have not been getting all we could be for the amount of fuel we have been burning.

The PRT, Supercharger, and Turbo Supercharger all take HP to run but they all give back more then they take. The differance between the PRT and the two Superchargers is that the Superchargers cram more air into the combustion chamber and need more fuel to maintain the proper fuel/air ratio were the PRT puts the power directly into the crankshaft. The advantage of a Supercharger over a PRT is that the Supercharged engine can maintain sea level HP up to a much higher altitude were as the PRT is a normally aspirated engine that looses power with altitude. The Wright R-3350 Turbo Compound engine has both a PRT and a Super Charger.

The PRT is 60 year old technology that is at the very end of its usefull life in its current application. I have seen experiments with PRTs in cars but they always seem to fade away. I don't know what the problem is. It might be a heat issue or a speed variation problem or a coupling issue or maybe it's just not enough power for the trouble. Seems to me that it is less trouble then a IMA with more benefits. Also seems to me that "THEY" ought to be smart enough to figure out a way to make it work if they really wanted to use it.....Louis