OT: Car runs on air ?

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** Hi to the regulars,

anyone been following the story of the plastic car that runs on compressed
air?

http://rawstory.com/news/2007/Air_car_runs_on_compressed_air_0104.html

My info is that compressed air is held in carbon fibre tanks at around 4500
psi.

Crikey  -  I bet there is one * hell of a loud bang * if it ever bursts  !!

The engine (which I guess has some metal parts) emits cold air as exhaust  -
used as air conditioning.

Initial market is said to be in India.

Will compete with all the magic, flying carpets over there  ......




.....   Phil




Re: OT: Car runs on air ?
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I've been following that one, and it's 4500psi all right.

What worries me the most is that it's made by Tata motors. I've seen
their construction quality first hand at a warehouse in Bridlington in
England that housed a stack load of brand new Tata utes. You'd swear
they were second hand and had done 100,000km before they rolled out
the door.

Anyone remember the psi used in the Mythbusters "air cylinder rocket"
episode that shot a cylinder through a concrete wall?

Dave.

Re: OT: Car runs on air ?



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That's how Indians make things. Been there, done that.

Graham


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Hasn't Tata just bought Jaguar?  Heaven help us.

Colin



Re: Car runs on air ?

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You just have to do the maths to see that it's either a complete con or
close to it. You won't get far on a realistic sized storage tank at 300 bar.
Also, the energy loss in compressing air to that pressure for storage is
considerable, so OK the car irself might be efficient, but the refuelling
system is unlikely to be.

OTOH, the promotion of the thing has been very clever, treading a fine line
between feasible, practical and useful. Lots of suckers will part with their
dough. WC Fields would be pleased.




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Check out the news article below it backs up the point you make. The book
mentioned is worth downloading, makes for interesting reading.

http://www.theregister.co.uk/2008/06/20/mackay_on_carbon_free_uk /




Re: Car runs on air ?



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About bloody time too.

Politicians' blood should be spilt for the outright lies they've been
promoting. Gore first.

Graham



Re: Car runs on air ?

"Den"
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** Huh  ???

It has got nothing whatever to do with air cars or anything like them.

Fuck offffff   -   you PITA troll.





....   Phil







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yeah whatever you reckon phil...........



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Totally correct on all points. MDI turns up annually typically in the energy
groups, to a communal groan from the regulars.

Graham



Re: OT: Car runs on air ?



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Yes, the MDI 'air car' scam's been running around 12 years now.

http://www.youtube.com/watch?v=QmqpGZv0YT4


Note the "on sale next year" quip. It's been like that for years.
http://en.wikipedia.org/wiki/Motor_Development_International
http://www.mdi.lu/eng/affiche_eng.php?page=accueil


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Yes, Tata were daft enough to do some deal with MDI. Can't wait to see what
happens.

Graham


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Not that one, but it's something I've discussed a number of times.
Unfortunately the skeptics are right about the efficiency problems.
There are two real issues, and neither of them is about efficiency
of filling the tank (the excess heat can be recovered).

First issue is that to get down to a pressure you can use in an engine,
you have to pre-expand the air... and that discards the energy. Only
way to recover half(*) the stored energy is to drive the equivalent
of a high-pressure pump in reverse, and probably use hydraulics from
there.

Second issue is that adiabatic expansion means the whole thing freezes,
and you lose pressure ratio at much more than the volume ratio, due
to the temperature drop. If freezing isn't an issue, you can only
recover half the stored energy even theoretically. The temperature of
normal air expanded from 25C at 4500 PSI to ambient drops to somewhere
around 11 Kelvin. Try to stop *that* from freezing things.

Clifford Heath.

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"Clifford Heath"
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** OK -  so India's magic flying carpet makers have nothing to fear just yet
?




......   Phil




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Good points. I did a quick OOM calc based on a 200 litre tank (huge for a
small car), 300 bar when full and 10KW at the wheels. Assuming 100%
availability of the stored energy, which as stated in previous post you
won't get anywhere near, you get about 10 minutes run time. Not much of a
journey.



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It's carbon fibre, so very strong.  But hey - why don't you straddle one and
stab it with a screwdriver, just to see ....?

geoff



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