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re: increasing efficiency of water heating panels and a few ?'s
15 jan 2003
rd wrote:
>i searched thru http://rredc.nrel.gov/solar/ looking for where you obtained
>the 1050 btu for october in your below equation so that i can look up other
>months. then i can create an excel spreadsheet to play with varying
>insulation values and radiation data to come up with an optimized collector
>size and create an insulation cover of appropriate r value.
sounds like fun.
>can you please post the link to where i can find this data?
come to my house, if you like. i have a printed copy of nrel's solar
radiation data manual ("blue book.") page 146 concerns atlantic city,
affectionately known as station weather bureau army navy (wban) no. 93730.
from 1961-1990, the average daily sun on a horizontal surface in october
was 1050 btu/ft^2, with a standard deviation of 86 and 870 and 1210 min
and max. the average diffuse sun was 430, 1360 might fall on a mythical
clear day, and an average of 1140 btu/ft^2 fell on a south wall. this
might be interesting if you were to consider a south wall reflector.
>i find it incredible that boosting r value of the cover can have such an
>impact on collector area.
you and 38 skillion "pool professionals" :-)
>it's certainly logical to keep what you have and add to it rather than
>keep dumping heat into the ground, that is essentially a heatsink, not
>to mention the evaporation effects.
the main heat loss is to the air, even with a typical cover.
>i'll have to come up with a practical r 10 + cover that is not especially
>burdensome to my wife and children to remove, but that's another topic for
>another day.
how about a flexible raft that can sink to the bottom, under
a "solar cover"? with some straps at the edge to keep the raft
from sinking more than 6", it might also act as a safety cover.
you might look into t-clear (http://www.tclear.com) "heavyguard" roof
insulation panels. these 2'x4' tiles weigh 11 psf. the version with 2"
of dow styrofoam would be slightly bouyant.
or make a sandwich with 3'x5' sheets of 1/2" wonderboard on each side
of 2" styrofoam and some 2" pvc pipes for extra bouyancy when filled
with air. you might try this out on a 12' diameter ez-set pool, like
this, trimmed to a circle, viewed in a fixed font:
| 10' |
5'
--------------------- ---
| e | you might make it
3' | p | p | with 4 4'x8' sheets of 2"
-|----------------------- styrofoam bolted between 4.8
| | t | t | | 3'x5' sheets of 1/2" wonderboard
| | p p | p p | | on each side, with 6 10'x2" pipes
|e|----------p----------|e| 12' and 4 elbows and 4 ts and 1 cross
| | p p | p p | | in the center. it would be stronger
| | t | t | | with the wonderboard patterns on
------------------------- each side rotated 90 degrees
| p | p | from each other.
| e |
--------------------- ---
| |<-1'
you might float the cover automatically at night with a small piston
aquarium pump, or maybe a shop vac. have fun.
our solar heat in snow country (jan/feb 2003 solar today) article is
now on my web page. there's lots of other good stuff in this issue,
which is available at borders bookstores.
nick
nicholson l. pine system design and consulting
pine associates, ltd. (610) 489-1475
821 collegeville road fax: (610) 831-9533
collegeville, pa 19426 email: nick@ece.vill.edu
computer simulation and modeling. high performance solar heating and
cogeneration system design. bsee, msee, sr. member, ieee. registered
us patent agent. web site: http://www.ece.vill.edu/~nick
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