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Old 05-06-2015, 11:54 PM   #1 (permalink)
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Another compressed air car

Air-powered car wins $5 million on TV show Shark Tank


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Old 05-07-2015, 01:26 AM   #2 (permalink)
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The article says the air cylinders are heated? I wonder how they are accomplishing that?

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Old 05-07-2015, 08:27 AM   #3 (permalink)
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"The air tanks can be filled by any "commercial grade" air compressor at any gas station in 5 minutes, for about $2."

Several multi 1000 psi tanks can be filled from a 120 psi shop air compressor in 5 minutes!

I'm waiting for that explanation. At least you can use the exhaust for AC.

If you compress air you compress the heat contained in that air. If that air is allowed to cool when rapidly expanded, the heat content should be the same, but it would get very hot when compressed. Allowing it to cool is a serious waste of heat energy.

Maybe they transfer that heat energy to the engine from the pressure vessel.

Another problem not discussed is the fact that you are talking about air pressure at least 10 times the compression pressure of a diesel engine!

Think spontaneous combustion of any flammable lubricant.

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Old 05-07-2015, 08:33 AM   #4 (permalink)
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UPS was testing something like this a couple of years ago as a hybrid system tied to braking action, not sure how it ended up.

UPS is First in Delivery Industry to Test Hydraulic Hybrid Vehicles: 50% Better Fuel Economy and 40% Lower Emissions - Gas 2

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Old 05-07-2015, 12:38 PM   #5 (permalink)
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Its not really another air car, it is the mdi / tata airpod, this is only a US franchise zoned for Hawaii.
Having three wheels it is not actually a car, they call it an airpod.
Gas station charging - looks like they have their own high psi air compressor at the gas station.
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Old 05-07-2015, 01:35 PM   #6 (permalink)
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I thought the tata airpod was discontinued, the cold air from decompression was causing failures. Maybe these guys got a great deal on all the inventory in India and are planning to unload them in the US for $10,000 each, when they paid $100 each.......
You can get a low speed NEV already if you want to go slow, which the market has already spoken on that, people don't want to go slow.
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Old 07-06-2015, 01:23 AM   #7 (permalink)
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I read somewhere that they were working on a air engine made from carbon fiber So they could keep the weight down. Being that it was using air to propell the vehicle they were stating that it could be done without too much trouble.

What they could do to heat the cylinders is to have water channels in the block and just run the water through to keep the cylinders from freezin, by keeping them above a certain temperature it will keep them from freezing.

I believe the specs for the air vehicle I saw was about 3500 cubic feet compressed to 890 psi and could go between 150 and 250 mpg. The engine was a one liter three cylinder with really high gearing to utilize the high low end torque an air engine has. If these vehicles really work then they would be worth the price in the end.
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Old 07-07-2015, 09:00 PM   #8 (permalink)
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Originally Posted by Old Mechanic View Post
"The air tanks can be filled by any "commercial grade" air compressor at any gas station in 5 minutes, for about $2."
We seriously need an emoticon with smiley raising a flag that says "BS".
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Old 07-07-2015, 10:08 PM   #9 (permalink)
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Originally Posted by Old Mechanic View Post
Several multi 1000 psi tanks can be filled from a 120 psi shop air compressor in 5 minutes!
The compressors they used to fill my SCUBA tanks with were multi-stage monsters and the SCUBA tanks were cooled in a water bath during the process. The aluminum tanks have to be inspected for corrosion every so often as well. Maybe carbon fiber, painted black for solar heating, and active shutters to block sun when they are freshly jacked up might work better.

Mirror deletes, 80% grill blocks, wheel covers, 50 psi tires = 6% better MPG avg. over a year. Wheel skirts overcoming ethanol winter fuel mpg losses and more!
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Old 07-08-2015, 09:34 PM   #10 (permalink)
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890psi in an engine cylinder is pretty poor. Gas engines generate more pressure than that, diesels generate a lot more. Unless you're looking at a pretty long throw on the crank, that isn't a torquier engine than an ICE. Its big advantage is that, since it doesn't have to actually be turning to provide thrust, you can simply open the throttle and wait for the push's effect to accumulate into useful velocity.

In that regard it's a lot more like a steam engine than anything.

Some low-grade math! Given:

1-liter engine displacement. Assume two-stroke, single expanding.
3500 ft^3 storage volume = 98,000 liters of air.
Assume you get to use all of that volume at full power.

The engine can deliver its maximum output, drawing from that volume, for 49 minutes. That's actually not that bad when you think about it. The car probably won't need anything like its full power to cruise at speed.

Then physics steps in. You don't get the full power, you can't have the full volume. As the tank cools off the pressure falls off even more rapidly.

Frankly I'm not sure this belongs in the unicorn corral at this juncture. MDI keeps building prototypes that obviously work. The big sticking point is funding and market uptake.

Some of the details surrounding the AirPod, and a couple of ideas you suggested, however, are serious Unicorn Chow. The claim of a 5-minute refill is quite fanciful. A powerful compressor working to stuff 3400psi into an 80 ft^3 tank - 1/40 the volume you quoted - needs about 25 minutes. To do the job with the big tank you quoted would require a MIGHTY compressor, or else a lot more time.

I watched the Shark Tank teaser vid. One of the presenters mentioned using any gas station's air hose - big, big mistake. That's a fast way to lose credibility.


Lead or follow. Either is fine.

Last edited by elhigh; 07-08-2015 at 09:42 PM..
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