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Posted by Benign Vanilla on March 9, 2005, 4:22 pm
 
For fun...

I am thinking of building a DIY solar panel(s) array to heat a swimming
pool. I figured a good place to start would be to look at the internals of
an existing panel to see how they are designed. Does anyone know of a site
with photos?

My main area of interest right now is how to determine and accomplish the
prope dwell time for the water in the panel. IE, my current plan is to put
together pipe in a snaking fashion to maximize the time the water is "in the
panel". I plan to use 3/4'' copper. Would smaller pipe be better?


--
BV
Webporgmaster of iheartmypond.com
http://www.iheartmypond.com
I'll be leaning on the bus stop post.






Posted by Gary on March 10, 2005, 7:54 pm
 
Benign Vanilla wrote:

For swimming pool heating most people use the commercial, unglazed,
plastic collectors.  These are cheap and work well in a swimming pool
application because the pool fluid is cool, and the air is
(usually)warm so even though they are not glazed the losses are not
high -- in fact, on a warm day, the "losses" can be negative.  I would
take a look at these before you build something.  Searching on "solar
swimming pool heaters" will return many suppliers.

If you still want to have a go at building one, here is a story on one
project:
http://www3.telus.net/teeoff/solar
(note also the link he provides for another pool heater right at the
bottom)

Gary

Posted by Benign Vanilla on March 16, 2005, 6:02 pm
 
<snip>

<snip>

LOL. Currently bidding on several on eBay.


I may do this for fun. Thanks for the feedback.


--
BV
Webporgmaster of iheartmypond.com
http://www.iheartmypond.com
Help IHeartMyPond.com, by doing all of your eBay shopping via our
eBay Affiliate Link: http://www.kqzyfj.com/click-1609574-10357516 .
It doesn't cost you anything, but an extra click!



Posted by John on March 14, 2005, 4:55 pm
 I have had an interest in building a pool heater for too long.  Here are the
links that I have bookmarked.  It seems that the most logical and practical
DIY is a trickle collector.  Although I have not gotten around to it yet the
systems is as follows.

Lowes sells galvanized corrugated roofing, they have one that you can order
that has a center to center distance of just 1.5 inches. If memory serves it
is 24 inches by your length and a 15 footer ran about 22 dollars.  An array
of these painted black, mounted on the roof with piping and holes drilled on
center so the water leaks into each valley of the corrugated.  It runs down
the valleys, into the gutter, and diverted to the pool.  It is simple and
cost effective, automatic drain down and menial potential for clogging.
Drawback is evaporation, what amount I do not know.  It could be glazed, I
can get clear 5 mil mylar for free so I was thinking of covering with that
to prevent contamination (leafs, dirt, etc).  I bought a galvanized sheet
last summer, painted it black, it was near 190F after 15 minutes facing
south at about 40 degrees. I circulated water for about 20 minutes and had
an decent measurable increase (I forget numbers, just verifying it would
work)

My mental scheme is to secure galvanized piping near the ridge line serving
as both as mount and water delivery plumbing, another run of galv to mount
the bottom of the galv to. Water pumped up 24 feet, drains down to gutter
and into pool.  A diverter at the gutter allows it to be a regular gutter in
the event of rain.

Trickle Collector
http://www.geocities.com/davidmdelaney/shurcliff/shurcliff-trickle.html

Trickle Collector
http://www.lib.niu.edu/ipo/ip820520.html

Non tracking concentrator - This would be pretty neat to try and DIY but I
do not know how to calculate the curve
http://www.opticalenergy.com/solar-panels-home-industrial-commercial-collectors/

Tube and fin
http://www.anotherurl.com/therm/Self_Build_Solar/default.htm

Tube and fin
http://www.hhs.net/jbrown/jimsspot.htm

AST Archives
http://www.ece.villanova.edu/~nick/usenet/

If you find the magic bullet, please post it.  Enjoy
John


: For fun...
:
: I am thinking of building a DIY solar panel(s) array to heat a swimming
: pool. I figured a good place to start would be to look at the internals of
: an existing panel to see how they are designed. Does anyone know of a site
: with photos?
:
: My main area of interest right now is how to determine and accomplish the
: prope dwell time for the water in the panel. IE, my current plan is to put
: together pipe in a snaking fashion to maximize the time the water is "in
the
: panel". I plan to use 3/4'' copper. Would smaller pipe be better?
:
:
: --
: BV
: Webporgmaster of iheartmypond.com
: http://www.iheartmypond.com
: I'll be leaning on the bus stop post.
:
:
:
:
:



Posted by nicksanspam on March 15, 2005, 11:39 am
 

Where do you live? Is your pool shaded? Indoors? Covered when not in use?


Harry Thomason heated hundreds of houses that way.


About 0.1(Pw-Pa) lb/h-ft^2, where Pw = e^(17.863-9621/(Tw+46)) and
Pa = 29.921/(1+0.62198/w), where Tw (F) is the average collector temp and
w is the outcoor humidity ratio in pounds of water per pound of dry air.
For instance, w = 0.050 on average in April in Phila, so Pa = 0.239 "Hg.
If Tw = 80 F, Pw = 1.047, so the collector would lose 0.1(1.047-0.239)
= 0.081 pounds of water and 81 Btu/h per square foot.

NREL says 1520 Btu/ft^2 falls on the ground and 950 falls on a south wall
on an average 52.4 F April day with an average daily max of 62.6 in Phila,
so sqrt(1520^2+950^2) = 1792 Btu/ft^2 would fall on an atn(950/1520) = 30
degree sloped roof. In 8 hours, it might lose 8x81 = 648 Btu/ft^2 and
collect 1144 Btu/ft^2, net. A 24x32' = 864 ft^2 uncovered 80 F pool would
lose about 24hx864x81 = 1680K Btu/day (and 202 gallons of water), so you
might heat it with a 1680K/1144 = 1468 ft^2 roof which loses another
8x1468x0.081/8.33 = 114 gallons per day.

So, you _could_ do without covers in Phila, but...


In narrowish widths? How long would it last in the sun?


Or refill the pool...


You might use greenhouse polyethylene plastic, which costs about 5 cents/ft^2
and comes in wide folded rolls, up to 40x150', with a 4-year guarantee. It
won't last very long if it touches a hot dry roof You might stretch it over
shallow doubled 1x3 roof bows or inflate it over the roof with a small blower
or suspend and contain it with ropes or straps under and over.

A 24'x36' shaded 80 F pool with an R1 cover would lose about 24h(80-52.4)864
= 572K Btu on an average April day in Phila. A square foot of covered roof
might gain 0.9x1792 = 1613 Btu and lose 8h(80-57)1ft^2/R1 = 184 over a day,
ie 1429 net, so you might heat the pool with a 572K/1429 = 400 ft^2 roof.

An unshaded pool with an R1 cover with 90% solar transmission might collect
1613 Btu/ft^2-day and lose 24h(T-52.4), so T = 52.4 + 1613/24h = 120 F,
theoretically-speaking.

Nick


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