Deep mesh collector test
nick pine
Nathan Hurst
> http://www.builditsolar.com/Experimental/DeepMeshCol/120116Test.htm
Excellent work! I find it hard to believe you were getting 1250W/m^2 though?
(I thought the maximum was about 1300W/m^2)
njh
Gary BIs
Those high pyranometer readings I get were hard for me to believe as well.
The first summer I had the pyranometer, I had a couple days in which even with
no snow to reflect the sun I got readings up[ to 1250 w/sm. I sent the
pyranometer back to Apogee thinking that it must need calibrating, but they
checked it and said it was right on. They also reported getting similar high
readings from time to time down in Ogden Utah. They think that it has to do
with a certain arrangement of clouds reflecting light. The high altitude also
adds about 30 watts/sm.
Sun on a clear day varies more than people think -- we can have days that appear
nice and clear and seem little different from each other, but the pyranometer
might read 900 on one day, and 1100+ on another.
One other thing that might be a factor is that I mount the payranometer in the
plane of the collector, and normally I point the collector at or close to the
sun. The weather station pyranometers are mounted horizontally.
I'm just getting ready to order metal halide lamps for the new sun simulator so
I can do some testing inside -- four 400 watt lamps which I hope will allow me
to do collectors up to about 2 by 4 ft.
Gary
Nathan Hurst
> Hi Nathan,
> Those high pyranometer readings I get were hard for me to believe as well.
> The first summer I had the pyranometer, I had a couple days in which
> even with no snow to reflect the sun I got readings up[ to 1250
> w/sm. I sent the pyranometer back to Apogee thinking that it must
> need calibrating, but they checked it and said it was right on.
> They also reported getting similar high readings from time to time
> down in Ogden Utah. They think that it has to do with a certain
> arrangement of clouds reflecting light. The high altitude also adds
> about 30 watts/sm.
Ok, I'm glad I'm not crazy :)
> Sun on a clear day varies more than people think -- we can have days
> that appear nice and clear and seem little different from each
> other, but the pyranometer might read 900 on one day, and 1100+ on
> another.
That makes sense, our vision is roughly logarithmic.
> One other thing that might be a factor is that I mount the
> payranometer in the plane of the collector, and normally I point the
> collector at or close to the sun. The weather station pyranometers
> are mounted horizontally.
>
> I'm just getting ready to order metal halide lamps for the new sun
> simulator so I can do some testing inside -- four 400 watt lamps
> which I hope will allow me to do collectors up to about 2 by 4 ft.
You might consider using white LEDs, 100W LED floodlights are now
available, which have the advantage that they can be dimmed, and are
quick to start. Having said that, the cheapest I can find for a 100W
unit is about $100.
njh
nick pine
with phosphoric acid to make a somewhat selective surface, with the
tops facing south. Maybe the can bottoms don't need holes, if warm air
flows out of the cans by convection and gets swept from south to north
by the very slow 2 fpm air.
> ... use this $40 air punch to make 2 holes near the top of each can and string them on horizontal galvanized wires that run through the studs...
>
> http://www.harborfreight.com/air-punch-flange-tool-1110.html
This could power it:
http://www.harborfreight.com/18-horsepower-17-gallon-150-psi-oilless-air-compressor-68066.html
With 4 holes near the top, the cans could be simply supported by a
wire that runs horizontally and vertically through 1" deep notches on
4" centers in the south edges of 2x8 studs, with a twitch stick to
tighten the wire.
But do we need 2x8 studs? Why not hang the can wires from double
curved 1x3 bows on 4' centers with 6" 1x3 spacers every 2' and 1x3
purlins every 4', before stretching a single layer of polyethylene
film over the bows and stapling weed barrier fabric under the bows?
Bucky Fuller used to ask "How much does this building weigh?"
Nick
nick pine
greenhouse polyethylene film air ducts instead? They might sit on weed
barrier over stone supported by wire mesh over wood pallets over
plastic film on the ground, inside peat moss insulation, along the
lower 4' of a 96' plastic film greenhouse wall.
A poly film duct can supply hot water for a house without elaborate
plumbing...
Nick
nick pine
plumbing...
this yard boiler scheme? We could spray cool water that comes back
from the house over the rocks below the poly film duct...
A Quonset-shaped yard boiler could have a polyethylene film roof with
peat moss under the north half and cans under the south half.
The heat store could have peat moss on top of greenhouse shadecloth on
top of inner Quonset hoops concentric with the outer hoops, then an
air gap, then a large poly film water duct, then shadecloth, then
pallets, then stone, then wire mesh, then pallets, then plastic film
on the ground.
Nick