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Compressed air powered vehicle


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#1 imaginesix

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Posted 21 January 2004 - 08:35

I came accross this site recently that you may all be interested in; a new small car being built in South Africa that is powered by compressed air. I shrugged it off initially as just a dubious alternative to batteries or flywheel energy storage, but there may be more to it.

Also, it was designed by one Guy Negre, who apparently designed F1 cars some time ago. Heard of him? Perhaps he was involved in pneumatic valve actuation then?

The powertrain is claimed to be very lightweight, even with on-board electricly-powered compressor pumping air to 300bar?!?!? CFRP cylinders store the air, and it is released in stages so it can be reheated several times to allow the energy to be extracted more efficiently. This also provides the opportunity for 'free' a/c.

I don't understand the technicalities so if any of you have an interest, have a look and let me know what you think, yea or nay?

New site http://www.e.volution.co.za/
Old site (more complete) http://www.e.volution.co.za/old.html

Can the engine be used in reverse to comress the air in stages? How well could such a motor operate in cold climates? They suggest the system can easily accomodate regenerative braking. I suppose the compressor capacity would be the limiting factor in designing a fully regerative braking system that performs at an equivalent level as today's cars? Anybody have any more info on this type of drive system?

Thanks!

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#2 kilcoo316

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Posted 21 January 2004 - 11:03

I read somewhere a year or so back, some french guys have patented and built a series of cars running on compressed air, and apparently (if I remember right) they were very close to being practical... would be nice and clean

#3 dosco

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Posted 21 January 2004 - 14:10

Originally posted by imaginesix
I came accross this site recently that you may all be interested in; a new small car being built in South Africa that is powered by compressed air. I shrugged it off initially as just a dubious alternative to batteries or flywheel energy storage, but there may be more to it.


New site http://www.e.volution.co.za/
Old site (more complete) http://www.e.volution.co.za/old.html


Interesting.

"Zero Pollution" neglects the cost in energy to compress the air in the first place. The site claims 200 km range (at 130 km/h) on "one charge" or "one tank filling." So you goto the "air station" and charge the tank.....and go 120 miles at 80 mi/h.....how much energy was expended in compressing the air at the "fill station" to begin with? Now everyone is driving one of these things.....and there are now a zillion industrial high-pressure air compressors all over the place....electrical energy consumption (and associated pollution hazards) will go waaaay up as a result.

That's the key.....again, I don't have any reference data at my desk here.....for example let's look at a turbofan aircraft engine (which is basically a big "air compressor"):

"For typical aircraft, overall efficiency ranges between 20 and 40%." Source: http://www.grida.no/...viation/097.htm

The only moving parts on a turbofan engine are the blades, which are supported on shaft bearings. The thermal efficiency of a piston engine is limited due to mechnical interfaces between the cylinder walls and pistons.

Lastly, I deal with high-pressure air a lot where I work. If there were ever any manufacturing problems with the "air tank" on the car, you could have disastrous results from tank explosions (that's not to say gasoline is any safer....).

Seems like the concept is really wishful thinking.....or selectively ignoring "unintended consequences" of the concept.

#4 dosco

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Posted 21 January 2004 - 14:11

Originally posted by dosco

That's the key.....again, I don't have any reference data at my desk here.....for example let's look at a turbofan aircraft engine (which is basically a big "air compressor"):


Dammit! I didn't preview my response (again) and got a "mad face." Sorry.....

Mea culpa....I will always preview responses.....mea culpa.

Aaaiigghh!

#5 Greg Locock

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Posted 21 January 2004 - 19:08

It seems to be a franchise from the original French aircar people. http://www.theaircar.com/

The website for that is a source of great merriment to anyone who is an engineer or physicist or financial analyst rather than a scam artist.

http://www.theaircar.com/tests.html - the best is the claimed range of 200 km. Sadly the only performance that had been demonstrated is a range of, not 150, or 100, or 50, or 20, but... 7 km. But by multiplying 7 by 28 to allow for various obvious improvements they get back to 191 km. Brilliant.

Let's see - the maximum crude energy (it isn't even half this in practice) in 340 litres by 270 bars is 0.34*270*10^5 J, so over 200 km that would give us 45 kJ/km. So at 30 kph that is an average power of 1/2 horsepower. Not a great deal to move a car.

http://www.theaircar...es_reports.html

is a semi independent report with some rather caustic observations. I don't know why they only quote this one paragraph

"1.5 General conclusions

MDI has developed the global design of the 34p01-4 engine, which is not running yet. A significant work for optimization and control is still necessary to lead to an available prototype. Moreover, the electrical consumption of accessories needs a specific design."

Obviously what they really need is a beam axle for the front suspension.



#6 dosco

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Posted 21 January 2004 - 19:27

Originally posted by Greg Locock

Obviously what they really need is a beam axle for the front suspension.


Excellent...... :rotfl: :rotfl: :rotfl:

#7 McGuire

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Posted 21 January 2004 - 23:00

How do they prevent the hose from tangling? :confused:

#8 masterhit

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Posted 21 January 2004 - 23:18

It would be interesting to see if this is yet another attempt from the ex F1 Life engine designers. There was talk of compressed air powered taxis in Brazil etc.

Those who remember the Life F1 team will never forget it being such a scam (or at best, hopelessly underfunded team) that they sometimes took over twenty minutes to complete a lap.

There was a report on Pitpass some time ago by Mike Lawrence about these air powered engines, and he was understandably skeptical given Life's previous *ahem* track record.

#9 Wuzak

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Posted 21 January 2004 - 23:56

Originally posted by McGuire
How do they prevent the hose from tangling? :confused:



:rotfl:

#10 Pascal

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Posted 22 January 2004 - 01:03

Guy Nègre might well be at least one card short of a full deck, but I doubt he is behind anything that could be described as a "scam", however unlikely his idea of a compressed air powered car sounds.

I first read about this guy in the mid-80's when he was trying to develop a rotating(!!!) valve system for F1, as well as a W12 engine to use it. He had contacted most car manufacturers, and had been consistently turned down with his idea. Not one to lose his faith, he kept going on a shoestring budget, and finally unveiled his engine on an old AGS chassis that was used as a testbed. As incredible as it may sound, he actually managed to run some promising tests of this prototype, but quickly ran out of budget afterwards. Oh, and as far as I know, he was never involved in any way in the catastrophic Life F1 team.

For years, I wondered what the hell had happened to this guys and his innovative ideas. Then, about 4 years ago, his name was mentioned on TV as he was doing the first trials of his compressed-air car in the South of France. Apparently, his idea is to sell the license for building this thing to some developing countries, and earn money from a system of royalties. If the thing never works, then I guess he won't get any royalties at all. That, and the fact that he's been on this idea for several years now, would make Guy Nègre the lousiest crook in in the automobile world these days...

#11 Wuzak

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Posted 22 January 2004 - 01:42

Originally posted by Pascal
I first read about this guy in the mid-80's when he was trying to develop a rotating(!!!) valve system for F1


A rotary valve is not a new idea. The problem has been in being able to maintain a good enough seal between the valve and its housing.

#12 desmo

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Posted 22 January 2004 - 04:11

I actually had some photos of Guy Negre's rotary valve system in prototype form on my old hard drive that died... *sigh* Salut et bonne nuit Monsieur Negre where ever you are.

#13 Greg Locock

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Posted 22 January 2004 - 10:45

Well, M. Negre is going to have some additional motivation to get his car working. One of the franchisees recently announced is Colombian. Now, it is hard to think of an industry in a third world country that might have big buckets of cash to splash around, and a desire to generate 'clean' cash... but the only one I can think of has a fairly rough and ready attitude to justice.

#14 skiericski

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Posted 25 January 2004 - 18:53

http://www.coateseng...Gallery/G1.html

Rotary Valve Head. I remember seeing these photos years ago, but I don't think this has gone anywhere in that time. Surprise, surprise.

#15 zfh10

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Posted 28 January 2004 - 23:28

Originally posted by Greg Locock
It seems to be a franchise from the original French aircar people. http://www.theaircar.com/

The website for that is a source of great merriment to anyone who is an engineer or physicist or financial analyst rather than a scam artist.

http://www.theaircar.com/tests.html - the best is the claimed range of 200 km. Sadly the only performance that had been demonstrated is a range of, not 150, or 100, or 50, or 20, but... 7 km. But by multiplying 7 by 28 to allow for various obvious improvements they get back to 191 km. Brilliant.

Let's see - the maximum crude energy (it isn't even half this in practice) in 340 litres by 270 bars is 0.34*270*10^5 J, so over 200 km that would give us 45 kJ/km. So at 30 kph that is an average power of 1/2 horsepower. Not a great deal to move a car.

http://www.theaircar...es_reports.html

is a semi independent report with some rather caustic observations. I don't know why they only quote this one paragraph

"1.5 General conclusions

MDI has developed the global design of the 34p01-4 engine, which is not running yet. A significant work for optimization and control is still necessary to lead to an available prototype. Moreover, the electrical consumption of accessories needs a specific design."

Obviously what they really need is a beam axle for the front suspension.

It is fine to criticise - can you summarise some concise reasons why you think this concept is a failure/flop/sham/? I'd be interested in your opinion.

#16 Greg Locock

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Posted 29 January 2004 - 00:56

Well, I'll repeat my reasoning concisely.

An average power output of 1/2 hp is what you could achieve on a bicycle, briefly. So, do you think you, on a bike, could tow a small car, with passengers, while maintaining 30 kph (20 mph)? That is what they are claiming.

Secondly, if they can demonstrate a range of 7 km, yet predict a range of 191 km, it seems to me that a more thorough analysis than merely multiplying it up by a series of factors is required. At the moment they have DEMONSTRATED the equivalent of a single trip across town while claiming to be able to drive between states.

Sure, I'm being critical. I can afford to be. I wrote the first ever vehicle fuel consumption/ performance program for a large car manufacturer, when I worked there as an intern. It's descendant was still being used 10 years later. I also had a large part in the simulation, design and development and construction and racing of the world champion solar car a few years back.

#17 dosco

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Posted 29 January 2004 - 15:25

Originally posted by zfh10

It is fine to criticise - can you summarise some concise reasons why you think this concept is a failure/flop/sham/? I'd be interested in your opinion.


Don't forget the "costs" of compressing the air to begin with.

The statement of "zero pollution car" is disingenuous because of the pollution brought about by creating the "supply" of compressed air in the first place.

#18 masterhit

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Posted 30 January 2004 - 04:56

Originally posted by dosco


Don't forget the "costs" of compressing the air to begin with.

The statement of "zero pollution car" is disingenuous because of the pollution brought about by creating the "supply" of compressed air in the first place.


Indeed - you don't get a bigger lie than that.

#19 desmo

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Posted 30 January 2004 - 05:09

Couldn't the same be said for any "zero pollution" vehicle that isn't solar or wind powered?

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#20 dosco

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Posted 30 January 2004 - 13:24

Originally posted by desmo
Couldn't the same be said for any "zero pollution" vehicle that isn't solar or wind powered?


Well, yes I suppose you could. If you want to take it further, you could even say that fabricating a solar or wind powered car itself causes pollution (epoxy, welding, fabricating electronics, etc).

The problem I have with the compressed air vehicle is the fact that:

1. The compressed air "fuel" requires a boatload of electricity to produce....and the electricity generation process creates quite a bit of pollution.

2. Air compressors are quite inefficient....especially the 2000 psi variety....and are mechanically unreliable.

3. The conversion of compressed air from high pressure to low pressure is inefficient.....

Adding all the "first order" inefficiencies of the "fuel supply" for such a vehicle, IMO, is comparable to the vast waste involved in petroleum-fueled vehicles. I'm not looking waaay downstream into all the other pollution caused by mining ores, welding, chemical production, etc etc etc. Which is why my thought is that claiming the "car is zero pollution" is BS because the car itself might be "clean" but the process of making the fuel (albeit a simple fuel and simple "manufacturing process") is really really inefficient.

#21 Wuzak

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Posted 30 January 2004 - 15:35

Wouldn't the car require extremely high pressure storage for the air or quite large receivers to have a useful range between charges?

#22 Bladrian

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Posted 30 January 2004 - 21:36

Stanley and White still had the best idea. ;)

#23 Rainer Nyberg

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Posted 31 January 2004 - 02:21

Originally posted by desmo
Salut et bonne nuit Monsieur Negre where ever you are.


Seems like he now Luxembourg based...there is even an e-mail address to the man himself here .