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Posted by mn_mn on May 11, 2009, 5:30 am
 


Thanks for the information.  That explains why people had to go
through steam to get any useful energy from heat

How about a "Hot Air Ballon Line" running up a km high line attached
to side of tower or building with attached small hot air balloons
pulling line up until at top they are collapsed to return to bottom to
be refilled, ,  , ,  or not.

Posted by williamsdavid65 on May 11, 2009, 11:41 pm
 

Suppose one of the balloons holds 1 m^3 of air at a temperature
of 400 K, and the surrounding air is at 300 K. The air would have a
mass of about 1 kg, in very round numbers, so heating it from 300
to 400 K will have taken about 4e5 joules of heat. (The specific
heat of air is about 4e3 J/kg./deg.) The buoyancy force on the
balloon will be about 0.3 kg wt, or 3 newtons, so if it rises 1 km
it will produce 3000 joules of mechanical energy. That's less
than one percent of the energy that was needed to heat the air
in the first place. Not a very efficient machine!

                           dow

Posted by mn_mn on May 14, 2009, 1:45 am
 On May 11, 6:41pm, williamsdavi...@gmail.com wrote:

Balloon powered machines or generators might be inefficient but, and
this is big, it is a simple machine so 1) it cannot break down, 2) can
use low temp heat like campfire or hot springs, 3) is easily built and
maintained (without lathe, high pressure boiler, anything).  Ancient
greeks could have built these ,, , , , ,and one at home could build
this if stuck in woods.

I wonder if balloon could lift water up watertower where it is dumped,
then when needed one would draw down water using water-motors or
electricity generators or whatever, ,, , or just gear down the lifting
power and lift a 10 ton weight,  ,,

Posted by williamsdavid65 on May 14, 2009, 7:45 pm
 

What would ancient Greeks have have made balloons out of?
Ditto for a modern person stuck in the woods.

I can imagine problems with balloons being blown around by wind,
and so on. Maybe they could be solved, but the machine would no
longer be cheap and simple.

                   dow

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