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  • From: "WILLIAM JONES" <billj AT harborside.com>
  • To: <homestead AT lists.ibiblio.org>
  • Cc:
  • Subject: [Homestead] Heat Engine: More Design Considerations
  • Date: Wed, 20 Jun 2012 03:49:12 GMT

Here's the cool part.  The bottles are just trash, and so can most of the
connectors be trash also.  The pressures involved are so low that it's quite
easy to make connectors and stoppers from used wine corks, drinking straws,
and sealing wax from old candles, or maybe even just tallow.
Say, does anyone remember a brief ad from the 60s in which they showed
"university" research being carried out into solar-powered heat engines? 
Mainly I remember seeing big expensive glass bell jars roasting in the sun. 
Can you imagine how much that must have costed?  Yet anyone could see that
most of the sunlight was just passing through the bottle without having any
effect.  Much more recently they did the exact same stoogy thing on
Mythbusters, after which they declared that solar-powered heat engines are
impossible.  Like maybe at least try painting the far side of the bottles
black.  Duh!
Most of it can be made of trash, it's true, but the one thing that has to be
fairly nice are the bladder floats.  There's a good way to do it.  Make a
protective cage for the flow by say, weaving twigs into an egg shape.  Place
the float inside the hollow of the egg.  Strategically glue the bag to the
twiggy frame in several places.  The idea is that the float bag must simply
remain organized, whether inflated or deflated.  It could otherwise become
twisted and fail to inflate.  Fortunately we never need more than 12 floats
or so.  After that it's probably best to connect multiple bottles in parallel
with straws and corks.
As cool as it all is, remember that each square meter of sunlight gives a
maximum of 1000 watts, but we'll be lucky to get even 1% of that.  The good
news is, when I tell you that a bottle produces a maximum of 0.2 watts, say,
it will be 0.2 honest watts.  In other words, unlike electricity, a 0.2 x 24
(bottles) engine will lift 4.8 pounds of water at a speed of 1 foot per sound
(actually the watt is inherently a metric quantity, it's more like 1 Newton
worth of water (about 1/4 pound) at a speed of 4.8 meters per second.
And we haven't even talked reflectors!


  • [Homestead] Heat Engine: More Design Considerations, WILLIAM JONES, 06/19/2012

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