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Old 02-24-2008, 01:25 PM   #11 (permalink)
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Quote:
Originally Posted by basjoos View Post
I wonder how the efficiency of a series pneumatic hybrid would compare with that of a series electric hybrid. A series electric hybrid is of course a small IC engine driving a generator, feeding a battery, which powers an electric motor. A series pneumatic hybrid would be an small IC engine driving an air compressor, feeding a pressure tank (insulated to retain the heat of the compressed air), which powers an air motor. If the tank was well insulated, then the air motor's exhaust temperature should be close to the temperature of the air before it was compressed, thus almost eliminating one major cause of pneumatic system inefficiency. So you would have the weight of the compressed air tanks versus the weight of the batteries. Also the energy conversion efficiencies of the electric generator, electric motor, batteries, and voltage controller circuitry versus the efficiencies of the compressor, air motor, and heat loss from the air tanks and air lines.
In theory, the air powered variant wouldn't have battery wear. But I'm not sure how their tanks fatigue. On the same coin - the tanks are storing an incredible amount of energy that, in theory, could be quite dangerous in an accident compared to a non lithium battery...

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Old 02-25-2008, 01:33 AM   #12 (permalink)
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They often talk about these cars having a huge air tank presurized to a simaler presure of a scuba tank, about 3,000psi, and that is alot of energy, not something you would want to get in an accedent with, or have built by the lowest bidder.
Also, if you are compressing air, yes your air tank is going to heat up and that is a bad thing as it will then hold less air, and as it cools down you will loose that presure, I've used a number of compressers for air tools that have cooling fins on the air lines coming from the compresser so that air going in to the tank is as cool as possible, the compresser is going to work more efficently that way, even if you were to store that heat, then as the air passes thru the air motor and cools it will condense and drop in presure, that is why if you can have a radiator that warms that cooling air, you will go farther on a tank of air, but that only works in warm places like India... where cars like this are being used.
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Old 06-14-2008, 11:00 AM   #13 (permalink)
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That's fer sure Ryland. When I take my 106 cubic foot 4350 PSI scuba tank to get it filled,
I made darn sure it's tied down to the cargo clips. I would hate to have that thing rocketing around inside my car.


I think driving around in an HPA car would a bit more dangerous than using regular fuels.

I once saw a kid using way too much pressure while filling his bike tires in a gas station.
I yelled at him to stop, but he kept filling it. When that little tire exploded,
it wrapped a section of tire around his face at about mach 1..
He wasn't seriously injured, but the abrasions & tire marks were on his face
for days afterwards.

My point? Even low pressure air (under 400 PSI) can be pretty dangerous.
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Old 06-14-2008, 01:54 PM   #14 (permalink)
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With all due respect,
Aren't you guys missing the forest for the trees?

It runs on air. AIR. Even if it got 20 miles to the fillup (with 3 dollars worth of electrcity) This technology provides a clean, and inexpensive alternative to fossil fuel.

It's like you guys are sitting on the fence waiting for the "water car" or something, except in the mean time the Europeans and Indians are using and perfecting the future.

I admire many of your advances on plain old ICE engines and 90's car bodies, but don't detract from the brillance of this advancment with safety concerns. Of all people, the community here should appreciate the virtue of not giving up on potential so easily.
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Old 06-14-2008, 02:47 PM   #15 (permalink)
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I know how much power can be stored in compressed air. I've used compressed air all my life. (Even drive nails & take off my lug nuts with it).

But, it would take a LOT of 3,000 PSI scuba tanks to get the kind of results you get
with one gallon of gas. One problem is the HPA tanks would all have to be made from
carbon fiber (which isn't real cheap). Or, the car would be way too heavy.
And if you wanted to maintain a smallish size, those tanks would need to hold a lot more than 3,000 PSI (200 bar).
More dangerous pressures and your home compressor would be VERY expensive.
Just check out the prices of a little home compressor to fill a 300 bar scuba tank..

My guess.. A car designed from the wheels up to be a plug-in EV would be < 1/2 the price of an air powered car with the same range and load capabilities.
When you added in the cost of compressor hardware, the air car becomes something that no one would buy.

Go Google up the all the news on the Indian air car. A lot of it is very old news. They were going to start full production a few years ago.
Why didn't they? My guess is, they just can't get the range they need,
at the price point they need.

Heck we could be driving EVs made out of carbon fiber and covered with
high output solar cells, but what would be the MSRP?

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Old 06-14-2008, 03:35 PM   #16 (permalink)
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Quote:
Originally Posted by Jigsaw View Post
With all due respect,
Aren't you guys missing the forest for the trees?
I sometimes think that the people who support ideas like air powered cars are the ones missing the point, air is just the storage medium, it is not energy and so far it seems to be a pretty poor way to store energy,
when compressing air there are so many issues and losses, things like lead acid batteries start to look really good n comparison.

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Old 06-15-2008, 02:57 AM   #17 (permalink)
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As a former 3 wheel City-El EV owner, I know what limits lead acid have, so until Li-on or lipos are alot cheaper and available to the masses, this advance appears closer to the ultimate goal.

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Old 06-15-2008, 08:26 AM   #18 (permalink)
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That rotatory motor looks really nice. That might be the way to go.
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Old 06-15-2008, 10:15 AM   #19 (permalink)
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I did a lot of research for a blog about air cars, the most interesting things I learnt were:
  • The air tanks at 300 Bar (4350psi) hold about the same amount of energy as gallon of gas.
  • In terms of efficiency "According to the efcf, the cars can have a theoretical compression efficiency of 46% and a tank to wheel efficiency of up to 84%, the report concludes that given 100MJ of energy a hydrogen FCEV could travel 42km, an air car 46 and a Li-ion BEV an impressive 133km."
  • Because of the huge pressure you have the same chicken and egg fill up infrastructure scenario as hydrogen to get longer than the 125km range of the tanks.
Check out the blog for the sources. I'd rather get triple the efficiency and range in an EV, but the potential cost for a mass produced one is nice, and the air tank versus battery replacement is a plus, but A well looked after battery pack (i.e. properly engineered production car) is going to last a long time, LiFePo4 batterys are looking in the 2000-3000 cycle range so I don't think battery replacement will be too big of an issue.

Cool technology but EVs are better
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Old 06-15-2008, 10:34 AM   #20 (permalink)
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I really like the air powered rotary motor. Looks like it's going to be super efficient and the fact that it's as small as it is means less weight and greater flexibility for auto manufacturers for designing cars since 1/3 of the car doesn't have to contain the engine alone.

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