Passive solar heating panel plans - Page 5

 Morris,


This is what I like about the design.

I'm a little twitchy here, replacing household heating load during
sunlight I can see, I don't see intrinsic heat storage, never less the
return on investment for that alone gives the design merit.

Heat storage is still something that needs to be considered when
compare active and passive systems.

Curbie

  On 3/8/11 9:07 PM, Curbie wrote:


I can't fault your twitchiness - the 100% solar heat wasn't even hoped
for when the first two new panels were installed. In fact, I made the
strongest case I could for three panels instead of two - and I was
caught completely by surprise when the two were enough to slightly
overheat the building through that first winter.

To relieve some of that twitchiness, start with the volume of air in the
heated space. Once you know the volume you can approximate its mass, and
from that you can calculate the amount of heat energy in that mass of
air at room temperature. Now calculate the mass of storage media needed
to store that much heat at the same temperature. Knowing that, you can
use the density of the storage medium to calculate the corresponding
storage volume.

Note that that volume of storage is what's needed to raise the
temperature of all the air in the structure to whatever you called room
temperature exactly once - from a /very/ chilly -273.15˚C!

If you DAGS on [alt.solar.thermal]+"Physics help please" you'll see how
I muddled my way (with some expert help) to grasping why things played
so unexpectedly well. Somewhere in the thread you'll find a short
program that I wrote to do the calculation - and I'd guess that you
wouldn't have any difficulty adapting that to a spreadsheet.


Heat storage needs to be considered no matter what - but the thermal
mass required has nothing to do with whether the method of heat
acquisition is active or passive. :)

--
Morris Dovey
DeSoto Solar
http://www.iedu.com/DeSoto/

 On 3/8/2011 4:56 PM, Morris Dovey wrote:

Wonder how much homepower mag pays for an article....??

thinking again....<grin>....have fun....sno
--
Correct Scientific Terminology:
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Theory - a hypothesis that has been checked by enough experiments
  to be generally assumed to be true.
Law - a hypothesis that has been checked by enough experiments
  in enough different ways that it is assumed to be truer then a theory.
Note: nothing is proven in science, things are assumed to be true.