Homestead mailing list

["WILLIAM JONES" <billj AT harborside.com>]

Don Bowen wrote:
On 6/16/2012 9:13 AM, WILLIAM JONES wrote:
>   The device sits on a pond, allowing the air in each bottle to cool during 
>each cycle.  So when sunlight strikes the top bottle, its float inflates, 
>causing the device to tilt over, exposing the next bottle to the 
>sun.http://home.earthlink.net/~clanl/buoyancy.gif
In the seventies several devices like this were tried.  The most 
successful used Freon but none were really useful.  Mother Earth News 
built one that used propane tanks.  A sun heated lower bottle would boil 
its contents which would move to the opposite bottle. The heavier bottle 
would cause the wheel to turn.  The problem was the speed of the wheel, 
it was very slow, so slow to not be useable.
At the same time experiments were made using a steam style piston engine 
using Freon heated by the sun in coils in the roof.  It worked but again 
the heat transfer speed was low.
The laws of thermodynamics cannot be violated.
-- 
Don Bowen           KI6DIU
One mistake that the layman will often make is to confuse speed and torque.  
He will automatically judge a faster device to be the more powerful, 
regardless of torque output.  But any homemade engine will always be a 
high-torque, low-RPM device, since I could never make any high-speed device 
that won't fly apart due to imperfections/asymmetries in its structure.
I'm thinking about 30 seconds total cycling time for a bottle.  The engine 
would be used to turn an Archimedean screw, which can turn quite slowly and 
still pump water.  I'll let you know after I do some more math.
As I learned from folks on this list, Freon and such are a waste of time, 
since the high molecular mass of such compounds gives them a very large 
specific heat capacity.  The best bets are hydrogen and helium, which would 
allow the device to produce 5 times as much power, but they both have their 
problems and they both leak out.  Hence good ol' air...
The gas cycles between a cool phase and a hot phase, a necessary condition 
for it to function.  No laws of thermodynamics have been violated.
Bill