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Concentrating Solar Energy on Evacuated Thermal Tubes With Stationary Mirror - Page 2

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Posted by Free Energy on December 21, 2006, 1:28 am
 
I am not trying to place multiple tubes in a single collector trough.
Nor do I need to to get the needed concentration.
If you need still more power, you can just use multiple tube/reflector
troughs spaced several times farther apart.
You can get several times increase, with a single tube, if the aperture
area is several times larger than the total tadsorber tube area.
Think of it, like the whole reflector getting larger relative to the
absorber tube's constant  diameter while the tube remains at the
focus, and you will get the idea.
I am also using a vacuum thermos type EVAC tube which gets a lot hotter
than the copper tube used in the link.
That's a good link, however.
 There are some reflective losses, but you can just increase the
aperture area to compensate.
The PRECISION of the reflector, does have to increase as the reflector
sizes grows relative to the collector tube, however.
At some large concentration ratio, the thermal movements from expansion
and contraction may begin to exceed that precision limit.
So your not going to get up to 500 suns like a good tracker can.
However, concentrating to several suns or tens of suns is indeed
possible.
By the way, despite the puffery in that link, the old Winston patent
dates to 1977, so the Winston Compound parabola Solar Collector is now
squarely in the public domain.

2006
Patrick Ward
19 Dec. 2006

With Best regards
FREE ENERGY
Patrick Ward
Richmond VA
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Posted by Rob Dekker on December 21, 2006, 7:49 pm
 



Understood. I also meant one tube per trough.
What I meant was, the spacing between the troughs (with one tube each) can not
be extended indefinitely.



Maybe I missed something.
How do you mean the precision has to increase ? This is a non-imaging reflector,
and thus it has no true focal point, other than getter rays to hit the collector.
How much does the precision affect this goal ?


How does your design for several tens of suns look like ?

For plain copper collectors (like the solargenix design) you could probably make
the spacing
3 or 4x the diameter of the collector (3 to 4 sol), but not much more (since the
troughs would get very deep).

For vac tubes, you can still make the spacing 3 to 4x the diameter of the
collector,
but since there is a tube around it, the effective spacing would be only 2x what
you could
get with regular tubes with a half-circle reflective backside, or ANY sort of
capturing
of light that does not immediately hit the tube's collector directly.

Now, 2x or even 4x (2 to 4 sol) is still nice, and will save tubes and will
generate higher temps in the collector.
But I do not believe you can get even close to 10 sol with this design.


We did talk about this compounded parabolic reflector in this NG several months
ago,
but I did not know that the patent was in public domain.

Thanks for your link ! It is a nice 'informal' overview of the design concept
(although somewhat deceiving because it does not mention the limitations).




Posted by Jeff on December 22, 2006, 10:39 am
 Rob Dekker wrote:

be extended indefinitely.

reflector,

collector.

make the spacing

the troughs would get very deep).

collector,

what you could

capturing

generate higher temps in the collector.

I haven't worked through the geometry so I may misunderstand this, and
my newsreader does not have the entire thread (Earthlink burp). The
troughs are running horizontally?

   Perhaps for a higher concentrating collector, it could track in one
dimension (vertically) with deeper troughs?

   Also, rather than moving the whole array I wonder if each trough
could be realigned, sort of like the way venetian blinds move in tandem.
Such a configuration could minimize overall height and make this a
better bet for roof mounting.

   Just thinking aloud, I could have this completely wrong!

   Jeff

months ago,


Posted by Morris Dovey on December 22, 2006, 11:12 am
 Jeff (in jBOih.2540$w91.2514@newsread1.news.pas.earthlink.net) said:

| I haven't worked through the geometry so I may misunderstand this,
| and my newsreader does not have the entire thread (Earthlink burp).
| The troughs are running horizontally?

Horizontally makes most sense in the context of this discussion. From
a geometry standpoint, there are actually _two_ configurations
possible using exactly the same geometry. I've posted a drawing (same
subject line) showing both to news:alt.binaries.pictures.woodworking
to illustrate.
|
|    Perhaps for a higher concentrating collector, it could track in
| one dimension (vertically) with deeper troughs?

Up to a point (depending on the size of the collector tube and the
focal length of the reflector), it might not need to track
mechanically...
|
|    Also, rather than moving the whole array I wonder if each trough
| could be realigned, sort of like the way venetian blinds move in
| tandem. Such a configuration could minimize overall height and make
| this a better bet for roof mounting.

Yabbut as soon as you incorporate moving parts and a control system
you're begging Murphy to come to the party. What's nice about this is
that it lends itself to design of a static system.

|    Just thinking aloud, I could have this completely wrong!

Give it a try... :-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html



Posted by SJC on December 22, 2006, 3:32 pm
 The Solargenix requires your to make "seasonal" adjustments.


be extended indefinitely.

reflector,

collector.

make the spacing

the troughs would get very deep).

collector,

what you could

capturing

generate higher temps in the collector.

months ago,


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