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re: a 12' non-cube
10 mar 2001
georges wrote:
>>the reflector would bounce dawn sun down onto a 3'x12' horizontal target
>>at the base of the north wall. the focus moves closer to the north wall
>>during the day until the upper edge of the reflector begins to shade the
>>base of the wall at a 45 degree sun elevation...
>nick, why not a stationary '2d' parabolic reflector with the long axis
>parallel to e/w
same thing, so far.
>and a copper tube at the focal point. you can pump water through the tube,
>and transfer the heat to a radiator in the house.
sounds more complicated and expensive, if the tube has to move, vs
the stationary reflector and large target above, and we need a pump,
vs thermosyphoning. and comparing apples to apples, we still need
some sort of large insulated heat store for multiple cloudy days.
>there'd be no need to move the reflector during the day.
the focal line moves north (and smears a little) as the sun rises,
in the system above, because of the geometry. nothing else moves.
>to accommodate the different elevation angle of the sun, you'd have to
>rotate the reflector about it's long axis ( or move the tube) as the
>seasons progress (~ 1/month)
if the system provides 100% of the solar heat need in january, it is
likely to provide 100% in all other months, with no adjustments...
but still, $198 for materials... seems to me it can be frugaler,
and it might work better if aimed a bit above vs at the horizon.
nick
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