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Solar air heating collectors that use columns of aluminum soda pop
cans or that use metal gutter downspouts as the absorber are quite
popular.
In this design, the supply air flows into a plenum at one end and is
distributed to the pop can columns or downspouts, the air then flows up
the pop cans. The sun striking the outside of the black painted
cans heats them up, and this heat is transferred to the air flowing up
through the cans.
One of the challenges for an efficient design is to get the
same flow in each of the pop can columns. Having unequal
flows in the columns makes for a less efficient collector with some
parts of the collector running hotter than they need to and losing heat
out the collector glazing.
When I built a
downspout collector for testing against other collector types, I was
unable to come up with a plenum design that gave an even
flow in the downspouts... I think that this may have been a
significant part of why the collector did not do as well in the
testing
as the the screen absorber collector.
Sooooo, if you are building or have a pop can or downspout
collector, how about testing the flow in each column, and see how the
flow comes out on yours. If its not close to the same in each
column, maybe you can experiment around with changes to the collector to
get the flow to even out?
Testing for even flow is easy to do, and coming up with a
collector/plenum design that provides even flow to all the can columns
would be a real benefit to a lot of collector builders.
You can let us know how your testing came out in the Comments section
below, or drop me an email --
Gary...
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