[Greenbuilding] solar heat collection
Corwyn
corwyn at midcoast.com
Thu Jul 5 13:17:48 CDT 2012
On 7/5/2012 9:19 AM, Clarke Olsen wrote:
> All heat exchangers have a problem; transfer can never be total.
True, but I was trying to avoid complicating the explanation to try to
get the idea across.
Shouldn't running through the
> greatest differential extract the most? I can appreciate the concept of obtaining a high temp. in the
> upper strata, but storage considerations suggest the efficiency of more uniform temperatures.
How's that? Stratification allows the greater efficiency I
demonstrated. If the whole tank is one temperature, you are limited to
that temperature. If the tank is stratified, you can extract heat into
a higher temperature region, while still maintaining a lower temperature
region in which to extract heat, once the incoming water has cooled
down. It is a way of maintaining the greatest differential, which is
not available to a system that is uniformly at a given temp.
You will note in my explanation that the temperature of the outgoing
water (back to the collectors) is lower in the top down approach. This
means in essence that the water has seen a greater differential, and
thus more efficient heat exchange. The water is 7.5° colder, which also
means that the collector will function more efficiently.
Thank You Kindly,
Corwyn
--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
http://www.greenfret.com/
topher at greenfret.com
(207) 882-7652
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