Hot air vs hot water

[liderbug]

I want/need to add some BTU to my shop area. Garage faces southwest, shop is on the back/northeast. I've measured and drawn out plans for a popcan panel on the south facing roof with ducting from roof to shop. That leads to feet of ducting through a very cold garage area. So now I'm thinking of a large version of an experiment I did 20+ years ago. I was able to get a 2x4 piece of polycarb. twin wall and pumped black water (80% water 20%glycol and $0.79 black Rit dye). I seemed to work really good, 220 BTU/ft2/hr. There was the panel, a pump and a heater core from the junk yard. I'm thinking the tubing (vs ducting) would be easier and much more flexable.

I've done [search] and haven't found anything.

Thoughts?
Thanks.

[russ]

Doesn't seem lıke the dye would be necessary - the fluıd ıs behınd one layer of polycarbonate already?

[liderbug]

It was an experiment by ? Battelle Inst. ? (reported in PopSci????) - the thought process was: 1) heat the water (transfer medium) directly, 2) when not needed just turn the pump off - drain the system - and the reflective underlayment would would keep the panel cool. See: http://www.osti.gov/energycitations/...sti_id=5140027 or Google "black liquid solar collector"

But back to my orig question - The design of my garage/shop southwest facing ... really doesn't lend itself to hot-air. So I'm looking for thoughts on which way to go, has anyone built a "black liquid" panel? etc.

Chuck

[liderbug]

P.S. to above post

http://opus.ipfw.edu/cgi/viewcontent.cgi?article=1108&context=etcs_seniorproj_mcetid

says "... is absorbted directly ... 37% more efficient than flat, black panel." I would assume this is because the panel is cool and the hot water is carried off quickly.

[raydias]

Have you checked out the Build It Solar web site. They have a lot of projects on both space and water heating.

http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

Maybe a radiator type setup with a solar water heater. You could build the solar water collector as a stand alone rack if you have the room. Put a storage tank in garage and pipe the Hot water to the radiator in the shop.

http://www.builditsolar.com/Projects/SpaceHeating/TomLargeCol/TomCol.htm

[russ]

http://opus.ipfw.edu/cgi/viewcontent...iorproj_mcetid
says "... is absorbted directly ... 37% more efficient than flat, black panel." I would assume this is because the panel is cool and the hot water is carried off quickly.

Most likely it is because it is a one off university study that was meaningless

[liderbug]

I finding something strange. If you Google for black liquid solar panel you get a lot of references, but all (so far) are educational or commercial or ... patents - nothing amateur/home built, no mention in any forum I can find. What I find, examp. http://www.sciencedirect.com/science...38092X75900572 and they read "if you're going to pump a liquid, make it black...".

Hmmmmmmmm......

[Mike90250]

There was the panel, a pump and a heater core from the junk yard. I'm thinking the tubing (vs ducting) would be easier and much more flexable.

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[inetdog]

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