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DIY Solar Thermal Panel

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Posted by schooner on June 24, 2006, 5:06 pm
 
http://www.treehugger.com/files/2006/06/diy_solar_therm.php

Thought some of the regulars here might find this amusing.



Posted by Mary Fisher on June 25, 2006, 4:14 pm
 



Posted by Zombie Wolf on July 2, 2006, 4:37 am
 

The only flaws i can find in this device:

1. It's too small to really gather much thermal energy.

2. Nowhere does it mention a collector plate to collect the heat. The tubing
has far too little surface area to collect much.

3.  the idea that this little collector would have the ability to heat even
a moderately sized pool is rather silly. Having just built four 4 X 8 solar
heat collectors and wrestled with the associated math, I find that each
collector (with a proper collector plate under the pipes) will gather the
equivalent of 3 KWH of heating energy per hour. A properly built collector
will gather about 1 kilowatt per hour for each square meter of collector
surface.

4. the back side of the collector is probably un-insulated, which will lead
to some large heat losses through the back of the collector box. even if it
was constructed correctly otherwise. Without the collector plates, there
isnt much heat to lose, so not to worry on that score. You may think a
90-degree day is "hot", but to a solar collector operating in the 195-degree
range, its a cold environment, and a big heat loser.

5. The serpentine tubing from the refrigerator is far too short, by about 15
feet, to do the job. It took about 60 feet of 3/8 inch tubing to build each
one of mine. closing the serpentine bends closer together will only serve to
reduce the collector plate area, and will produce little heat gain. Square
collector plate area is square collector plate area, period. Remember, it's
the collector plate that collects the energy, NOT the pipes. The pipes only
serve to pick up the energy from the collector plates, which means they will
have to have a good thermal bond with it, something i think may have been
neglected in this design.



Posted by schooner on July 2, 2006, 10:31 am
 Exactly, that is why I found it amusing, far too small to be useful with
lots of other issues as you noted.  Concept shows how the process works but
certainly isn't going to heat even a toddlers pool.



Posted by Jeff on July 2, 2006, 3:11 pm
 Zombie Wolf wrote:

For all the flaws, it actually works.

It heats 40lbs of water 40F in 2 hrs in what looks like about 4 square
feet.  That's about 200 BTU's /hour per square foot. Rather remarkable,
if not unbelievable since it smokes your properly built collector by 50%.

It's all rather remarkable. You can collect dead refrigerators making
solar collectors out of the condensors and a wonderfull childrens
playground out of the discarded shells. Or maybe not...

What I find interesting is that it works at all. Seems to me that the
reflective box is trapping all that radiant which is being soaked up by
the condensor, a concept much closer to air collectors than the way
water collectors are traditionally made. How about some analysis Nick?

   Jeff



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