Flat plate systems

 I have been studying for some time a website www.solartwin.com

I have no connection with this company at all I must say to start
with.

But I am interested in this system for a Homebrew setup. I have two
sheets of ally and I plan to squash black rubber tubing in between
them.

The sheets are 8 foot by two foot.

I have a few questions people make like to give there opinions on.

Do I lay the piping 15 mm id from side to side or up and down

Does anybody here know of a source of such tubing

On a 8 * 4 sheet how much tube should I use

What type of matt black paint shall I use to paint the ally sheets

Hope to post some pictures here when done

regards david

  D Smith wrote:
...

You only need the ally for the front so you might do better by
routing grooves into foam sheets (or wood), laying the tubing
in these and squashing the ally on top.


I'm no expert in these things but I think I can offer some suggestions.

Since you're doing this yourself, you'll probably want to go with a
serpentine design of one long tube rather than a grid of tubes with
manifolds along two edges. This serpentine method means you'll lose
a little efficiency but it takes less effort to build and there is
less chance of leaking.

Since each bend in the tubing causes more resistance to pumping
water though it, it's a good idea to reduce the number of bends.
This means laying them straight along the long edge.


Silicone tubing can be found in most home improvement and hardware
stores. It's usually clear. The color doesn't matter because it'll
be under your collector and not exposed to sunlight anyhow.


I think this depends on the thickness of your ally. I'm sure someone
can give you heat flow calculations but off the cuff, I would guess
that you wouldn't want to space those tubes more than, say, 4 inches
from each other. This would mean 12 runs of 8 feet, plus around 2
feet on each side for the bends. About 100 feet of tubing.


If I recall correctly, the best thing is a black chrome treatment but
that's probably outside the budget of something like this and will
only add a small percentage to it's performance. I would say any
black water based paint should do.

Anthony

 
"D Smith" wrote >

With rubber or silicon tube it would be easier to serpentine it horizontally
top to bottom with multiple circuits in parallel to keep flow resistance to
a minimum. The back sheet could be wood. There would not be very good heat
conduction between the AL sheet and the water contained in the rubber tube
so I dont know how efficient this setup would be. The sheet could be 1mm
thickness with tube spacing 75mm (3 inches). This setup would not handle any
water pressure.

Black self etching primer, several thin coats.

Best of luck.
Mike Scaife (NZ)

 D Smith wrote:

hi david , you can buy alu ready pressed , it go's under the name "heat
spreader plates" they are used for under floor heating with suspended
timber floors .
I don't want to put you off using solar heating for home brewing but
there are very good low wattage thermostatic immersion heaters for this
purpose , brewing works best with a stable temp .  why not use the
panels for domestic hot water instead ?