Really? I was under the impression 65% of the incoming solar radiation
was IR and NIR. Well I was thinking of putting flat black paint on
copper pipes and having a sun tracking parabolic mirror beneath them. I
was just wondering if anyone had any data on flat black paint types as
the last post indicated they can have large variances in absorbtion.
Joe
bob allen wrote:
Howdy Joe, don't stop with IR, you want to absorb all wavelengths- there
is more energy available in the visible/UV than the IR. Any flat black
material will absorb all wavelengths (not counting high energy stuff
like gamma rays). what you need is a material which not only absorbs,
but also conducts the heat absorbed rather than radiating it away in the
IR. (Wein's displacement)
Joe Street wrote:
Do you have any information on IR absorption of common black materials,
ie flat black paint types which are resonably good? I plan to do
something with it one day but would like to make something myself of
reasonable efficiency rather than buying a turnkey solution.
Joe
Hakan Falk wrote:
Joe,
In Israel you will see the same, but with efficient solar panels
built together with an insulated storage. It is however an enormous
difference in efficiency. The black cisterns have a very low
efficiency and you can only collect some warm water at the end of
sunny days. The main functionality of cisterns on the roof, is to
give distribution pressure. It is also very large differences in the
coloring methods, what is looking black to us, can have very
different absorption factors. A Swedish company is the market leader
in delivering the solar collection elements for solar panels. They
deliver them in rolls of double black colored copper sheets. Before
mounting they are cut to size and pressurized to form the space for
water passage. Efficient solar panel construction was researched
around 40 years ago in Almeria, Spain, a joint project between
technical universities of Sweden and Spain. The Swedish part was
managed by prof. Folke Petterson, KTH, who also used some simulation
work with the energy transmission program that we have.
Hakan
At 00:40 28/04/2006, you wrote:
Almost every house and building has a big black cistern on the
roof. The are everywhere you look.
Joe
Hakan Falk wrote:
Joe,
Yes, but Mexico it is a bit larger and more people than Israel and in
total they do not have the same density, but last time was around 15
years ago and Israel the last time was around 6 years ago, China 5
years and Brazil last time was only 2 years ago. Time goes very fast.
Still, I doubt it, considering that Israel is a export producer of
thermal solar systems also.
Hakan
At 21:03 27/04/2006, you wrote:
Hakan Falk wrote:
Zeke,
Solar thermal hot water is the cheapest and most efficient solar use,
I do not understand that the use is so low. This except Israel, where
you can see solar for hot water on almost every house. .
snip
Ever been to Mexico?
Joe
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