From: mung_me@att.net   
      
   On 1/23/2013 5:14 PM, Morris Dovey wrote:   
   >   
   > Over the past month I've put together a web page describing a passive   
   > solar heating panel capable of providing 100% of the heat needed to   
   > maintain a comfortable temperature 24/7 in a conventional structure with   
   > reasonably good insulation and which is reasonably snug. The panels need   
   > to be installed in unshaded south-facing walls.   
   >   
   > These panels work reasonably well in overcast conditions and will   
   > produce heat whenever there's enough sunlight to read a newspaper. They   
   > work unreasonably well in clear-sky direct sunlight.   
   >   
   > Five years' experience in central Iowa indicates that each square foot   
   > of panel area can heat approximately 125 cubic feet of air with enough   
   > additional heat for storage to maintain that much air at a comfortable   
   > temperature for more than a week of completely dark days.   
      
      
   I've had a bit more time to go through this, although I haven't absorbed   
   it all.   
      
   It seems to me that you must be close to optimum, as far as getting the   
   amount of heat out of this. That you can generate heat with so little   
   light is striking.   
      
   A few notes.   
      
   I notice that you said a thin coat of gloss worked better than flat   
   black. This strikes me as similar to the way selective coatings work.   
   The absorption is slightly lower but the re-radiative losses are much   
   less. Certainly important in a cold climate.   
      
   I note the distance from the absorber fins to the glazing and the back   
   is on the order of a half inch. Larger distance seem to create their own   
   air currents and are counter productive, that was not obvious to me!   
      
   I also note your point that the object is to heat the air and not the   
   absorber! I've made some progress here, IR measurements of my absorber   
   (black felt) show it be a good bit cooler than the air between it and   
   the glazing. In my collector I'm pulling air from the collector and   
   pushing it into the old air vents.   
      
   The fin rolling "machine" is very interesting. I made a series of jigs   
   to form aluminum around the copper risers. That and riveting it all   
   together was extremely exhausting. Perhaps some details of the machining   
   would be useful.   
      
   I've altered my own solar air collector several times as money and   
   experience has allowed. The current geometry is too much depth, but that   
   was largely determined by the geometry of the house and the jalousie   
   windows. On the plus side the cats love to spend time inside the   
   collector (the house side).   
      
      Cheers,   
   Jeff   
      
   >   
   > My plan is to add both English and metric 3-D DXF/DWG files and an   
   > assembly animation, and to clean up some of the stuf   
      
      
   f that I don't think   
   > I presented as well as I might have. I didn't hold off because I have   
   > friends outside the US who need the info now.   
   >   
   > The web page will remain a work in progress for some time. If you find   
   > the content interesting, I suggest linking to the page rather than   
   > downloading a snapshot - and I ask that you not re-publish the page or   
   > any of the content until I have it in final form.   
   >   
   > The page is at http://www.iedu.com/Solar/Panels   
   >   
      
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    * Origin: you cannot sedate... all the things you hate (1:229/2)