Serpintine versus grid

Share with us your alternative energy ideas and projects. Tell us about your experiments, no matter how far-fetched they may seem.

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Which do you think is better?

Poll ended at Wed Jun 17, 2009 10:26 pm

Grid Design
1
50%
Serpintine Design
0
No votes
Haven't got a clue just like to take polls!
1
50%
 
Total votes: 2
DigitalDreams

Sat Apr 18, 2009 10:26 pm

After looking at Gary's two designs I have to ask which design has better yield.

I realize that doing the serpentine design in copper would be some
what harder to do and the grid in pex would require many more connectors which having not worked much with pex I assume are a
little spender than copper.

Reasoning for asking this is I built my hot air solar panel Number 1
using aluminum tubing in a serpentine design and cut in time from
sun hitting it to kick on is about ten minutes and it will blow 110 to 130 degree air all day and never cutoff and I have a much large cfm fan on it than most of the hot air panels I have seen. And it is my belief from plotting it over a number of days that at least two things
are positive ,and that is that, the longer the medium takes to get to the exit point the higher the temp and that on hot air solar that the
more turbulence you can create in the air stream the better the mix.

Water or a mix thereof reacts different from air but desired effect is same in the end, heated transfer medium.

So in summary is it better to make it take longer to get through the panel for a higher exit temp or is the grid design which would move more through but heat in a more cascade effect better.


Gary Gary
Posts: 16
Joined: Mon Mar 12, 2007 9:07 am
Location: Bozeman, MT
Contact:

Mon Apr 20, 2009 9:56 am

Hi,
If the flow rate is the same through the collector, the temperature rise from inlet to exit should be the same.
On the grid one, the temp rise will be from bottom to top of each riser, and on the serpentine it will be from entry to exit, but it should be the same.

The solar input to the collector is the same for each case, so BTU absorbed is the same. Since the flow rate is the same, the temperature increase is the same -- at least thats my 2 cents :)

It will take a little more pump pressure for the serpentine collector.

Gary

DigitalDreams

Wed May 06, 2009 6:28 pm

Thanks for the input Gary guess I never looked at it from that point of view, I tend to over think some projects.

Have Looked at your setup on build it solar and other than the
storage tank design I think I am going to use your idea and the grid
type panel.

One question which I may have just missed on your web pages is weather you heat solely with the solar or do you have hot water
backup and also what did you use to calculate spacing on pex in floor
loops.

Also did you use that high efficiency tubing from your shed to house like they use for outside corn furnace boilers.As a guy I work with
has 3 building heated off a corn boiler and said the tubing works well but is relatively spendy.

Also is your system zoned.
As my system will be built into a attached green house/solar shed
I guess I better ask have you used the system in reverse during summer as a cooling system as I had the idea that maybe running the panels on summer nights to cool the tank and using a heat exchanger design with fan to extract cool air off it by installing a ceiling duct system might work kinda like a swamp cooler but not injecting all that moister into the air.Or am I just shooting myself in the foot with this idea.

Gary Gary
Posts: 16
Joined: Mon Mar 12, 2007 9:07 am
Location: Bozeman, MT
Contact:

Sat May 09, 2009 11:00 am

Hi,

We still have our forced air furnace, so it is our backup when there is not enough solar -- this happens a lot as our house is pretty large and not as efficient as I would like.

The insulation scheme we used on our buried pipe is shown on the "
Trench" page -- I think its a pretty good way to go -- it allows high insulation values at a pretty low price. Most of the commercial solutions don't really achieve a very high R value. Good insulation is more important on solar than an outside boiler.

We have 5 floor loops all on one zone -- the control system is very simple.

Gary

DigitalDreams

Mon May 11, 2009 5:13 pm

Thanks Gary you have made the job of building a setup much easier
with your answers to my questions.
I will post my setup to here and build it solar when it is finished if my gains are comparable to what I see you have gotten.

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