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Wed, 22 Aug 2001 10:16:34 +1200 |
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>I am thinking of making a solar melter.
>
>I understand that the design is nothing particularly difficult, but I
>wonder if
>there is any necessity to use glass on top, or if plastic will work as well --
>assuming it does not melt.
Several modern plastics, e.g. polycarbonate or modified acrylate
with glass fibres cast in, will certainly take the heat fine - I have
used them on solar water-heaters, which run somewhat hotter than a solar
wax-melter, and they last many years developing only slight cloudiness.
But scrap plastic of suitable area is generally harder to come by than
scrap windows. And if it is non-flat - say, corrugated - you will have
to fit it to a frame of some sort. I see no point.
In many places, it will be easier to get a 'demolition' window,
complete with hinges or at least still having an entire wooden frame onto
which hinges can be screwed.
Any wooden cross-members are a non-problem; the incoming solar
radiation is hundreds of watts per square m, and even if the box under the
glazing is just a big drawer or other simple wood container, with no
special insulation, the wax will melt within a few hours. This is not a
case of needing to maximize efficiency; considerable losses can be
comfortably tolerated.
Of all functions that can be subserved by solar energy, this would
be one of the most clearly ahead of all rivals. Go solar!
R
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