09-18-14 - Another radical light car for Paris. This one is 2100 lbs and uses Air/Hybrid to get 141 MPG. Are the French on a roll?
01-25-13 - Peugeot Cirtoen to Introduce Compressed Air Hybrid by 2016
09-07-12 Tata AIRPod
07-05-11 - Tata Air Powered Car to be Introduced in India
02-26-09 - Yet one more way to use compressed air for braking recovery from ETH Zurich
First posted 01-19-08:
And it's not even about the car!
(note - whoever owned the MDI page when I posted this blog has diverted it to a new investment group and broken some of the links below. I have redirected them to the French or Guy pages as well as possible for now - thanks to Chris from Future Net.)
Every now and then a an idea comes along that will change the world - and gets mostly ignored. Some of you have heard me talking about this new air powered car from MDI (Moteur Developpment International) in France which is now to be manufactured by Tata Motors of India.
MDI did a press release a few weeks back and it was handled like, well, another press release. The automotive press paraphrased a few paragraphs, but I wonder if they actually THOUGHT ABOUT what they wrote?
And when Tata Motors introduced their more conventional yet inexpensive Nano at the Detroit Auto Show last week, it got amazing coverage, but not ONE mention of this new air car to be manufactured by the very SAME company!
The highly touted Tata Nano is a cute little bug that will get more than 50 MPG - cool. But the MDI OneCat which is about the same size will go more than 3 TIMES farther on the same gallon of fuel! Did no one actually READ the spec sheet on the OneCAT?
To be fair, the objective of the Nano is low price, not mileage. And the OneCat is much lighter, which helps, but surprisingly, that's not the key to it's mileage advantage. Here's how they do it...
As almost everyone knows, the standard internal combustion engine is only about 30% efficient under the very best of conditions. This means 70% of the energy in a gallon of gasoline leaves the car as wasted heat.
The only heat that produces power is that narrow band of highest temperature that causes rapid expansion of air when the spark plug fires. Once the piston reaches the bottom of it's cycle, all the lower temperature energy from that cycle is wasted and must be pumped out the exhaust pipe.
If you add MORE heat at the point of ignition (higher octane), you get more power. But Carnot and his second law of thermodynamics limits us from using any of the heat BELOW the temperature of ignition. THAT is the primary reason for the INefficiency of the internal combustion engine. But what if we COULD use ALL of that heat?
CAT - Compressed Air Technology
Guy Negre of Formula 1 fame and his company, Moteur Developpment International have spent the last 14 years developing a new type of engine for automobiles.
Compressed Air Technology has been described as using air as fuel, but that's not quite right. The air works more like a battery. Guy's design actually uses a carbon-fiber air tank with up to 300 times normal atmospheric pressure driving a piston to give the car a range of 100 Km. You can think of this system as a standard compressor motor and air tank - except it's running backwards. The air tank drives the compressor, instead of the other way around.
So far, no big deal. Any advantage is a matter of strength, weight and volume per unit of energy stored in the "battery" - the carbon-fiber tanks helps some. But if a short range compressed air car is all they had, it wouldn't be very impressive. The next refinement is the key and I now believe it was created in response to the problem of freezing the engine as the air was decompressed. Whenever air pressure drops from 300 Bar to 1, the gas laws say the heat in that original volume is now spread out over a much greater area thus dropping the temperature. Guy's "fix" to this problem had a side-effect that I believe to be the biggest advancement in thermal energy extraction since the invention of the Otto-cycle in 1860! It effectively uses "wasted heat".
Guy Negre's brilliant innovation is to add a small fuel burner between the air tank and the motor. The heat from this burner not only keeps the engine from freezing up, it also extends the range for the compressed air tank by increasing the pressure of the air even more on it's way to the motor. Properly insulated, this burner could approach 100% conversion efficiency of the burned fuel. Here's the reason...
Small amounts of heat are not enough to turn over a reciprocating motor. But when you add a compressed air tank, it provides a pressure bias great enough to drive the motor on it's own. Now add the burner. Per the gas laws, the pressure increase is proportional to the heat added - it doesn't require a critical temperature of ignition! You could run it tepid or boiling - ANY heat adds power. It's just a matter of how much.
If you double the burn rate, you'll double the added expansion. Since there's no point of ignition, there's no critical temperature before this energy is extracted. ANY heat added by a burner (or other source) will simply add proportional expansion and energy extraction. Theoretically, most of the energy from a gallon of gasoline (or stack of firewood) could be used to drive the motor.
Check the spec sheet above. I assume these are actual measurements. The OneCAT will go 100 Km on air alone, but another 700 Km on only 10.5 (1.5 Liters per 100 Km x 7) liters of fuel! That works out to almost 157 MPG!
More Than JUST an Amazing New Car
MDI has a good chance of creating an amazingly efficient little car, and that's cool. But what's REALLY exciting are all the other potential industrial applications.
Considering generation and line losses when producing electricity, it may even now be more efficient to run Bi-Energy motors at the site of the application instead of buying electricity. Or we could boost mechanical power from solar heating. Or hot sewer water for that matter! ANY source of heat could be used. It's just a matter of degree and effectiveness.
OK. You'll still need electricity to provide the compressed air bias, but the rest of the energy would be more efficiently extracted - the hotter, the better. What about recycling the heat from air conditioners to drive their OWN motors? I'm not talking about perpetual motion here. There's no free ride. It's just that the heat is no longer has to be totally wasted. This approach provides an excellent possibility of dramatically increased efficiency in anything that needs a rotating motor and has wasted heat available. (Note - MDI was WAY ahead of me - I just found this link on their site... Further Applications - WOW!)
These ideas are worth more than just a press release.
It's a whole new way of thinking about energy!
More Air Car Energy Links...
Guy Negre Page
MDI and Indranet
Dr Louis Arnoux Interview
Others are picking up on using waste heat in this fashion - The VGT RoundEngine
... seeking simple answers to complex problems, and in the process, disrupting the status quo in technology, art and neuroscience.
Thursday, September 18, 2014
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