Ian's initial email

In the mean time while I putter about trying to understand non-

imaging optics I ordered a couple of books that might help me with
Solar stuff.  I also started on my air solar project.

I built a 35X35 cm panel to start playing with my thermal air panel
ideas.  The first iteration is very cheap and simple Gill insists
that I start doing photo docs so that's pending.

Construction is 3mm plywood back with 9x24mm frame around it.
Painted black and with an air director in the middle so the air path
is a "U" shape from inlet to outlet.  Both inlet and outlet are on
the bottom.  I obtained a 6cm muffin fan in Taiwan for the air source.

What I want to determine is how much power I can easily get out of
such a device.  The next, somewhat major step, is to scrape the rust
off my fluids skills.

I had to write to my old Prof at Carleton U and ask him about the
design of a rather simple flow measuring device we used in school.
The basic idea is a bellmouth entry and a pipe with a static tap 1.5
D from the end of the bellmouth. Apply Bernoulli's equation and make
a bunch of assumptions about the flow in a pipe.  The flow at the
static tap is assumed to be uniform (not fully developed) and from a
U tube manometer I can calculate P1-P2 where P1 is atmospheric (with
an associated velocity of zero).  We neglect gravity and assume
friction-less.  Anyway if done well it's quite accurate but it seems
to be a rare method, perhaps there are practical limitations I don't

So the idea is to get flow, temperature rise, and then be able to
calculate the power coming out of the device.  Then I can experiment
with different construction techniques where cost is the most
relevant I think.

These fans claim to be ~25CFM which seems like a lot and I don't
really believe yet.  TBD in the configuration I have that sounds like
pressure of around 11 Pascals (25CFM through a 50mm tube).  However
my math and dimensional analysis are suspect so....

I'll send out a few pictures of this hack when I get a chance.  This
is how I enjoy golden week in Japan :-)

Some day I'll have to actually finish one of these projects.  At
least this keeps my mind from atrophy.