Solar Power Generator Review

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Marcin Jakubowski

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Feb 28, 2009, 10:39:31 AM2/28/09
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Please view the discussion I had with Gang Xiao, inventor of a trough
system that he claims is better than Ausra and much cheaper than other
large troughs. He's intending this for the home market, and he
expressed interest in collaboration on the steam engine, as that's
also his engine of choice.

See his work:

http://wims.unice.fr/xiao/solar/index.html

Discussion:

http://openfarmtech.org/index.php?title=Solar_Concentrator_Reviews

I am inquiring on his licensing arrangements and fabrication
requirements.

Marcin

...

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Feb 28, 2009, 5:45:01 PM2/28/09
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some quick responses:

on requiring the use of heat transfer oil.  Thin schedual 40 carbon steel pipe will easily contain saturated steam at 250C (http://www.engineeringtoolbox.com/a106-carbon-steel-pipes-d_370.html), except for terrible corrosion.  I dont know what marcin is planning to use for his boiler tubes, but stainless steel from the scrap yard will hold fine.

I read through the pdf and couldn't figure out what xiao was using for his reflectors?  mylar?  how did he avoid the crinkling problems we have?

I don't like the idea of having the steam engine mass produced in china.  not that i'm against global trade or anything.  I think one can be fabed easily from a hard chromed hydraulic cylinder w/ piston which could be found scrapped. (now that i say that I'll have to stop by the scrap yard in san francisco and see what sort of hydraulic cylinder options are around).  If we wanna sell 1,000s then lets build them in house.

As far as making glass goes, I wouldn't count on it any time soon (like, if you want this concentrator to be an effective option within the next 50 years).  learning to engineer and utilize the equipment necessary to competitively produce exotic glass is quite a task, especially along side doing the same for steel casting (no foundry has been proposed for this yet), liquid fuel production, liquid oxygen production (for the steel foundry), etc.

I am very interested in evacuated tubes.  Borosilicate is sold in long tubes of any diameter you want.  I wouldn't know how to seal the ends (where the pipe comes out), but will keep my ears up.  Once that is answered, I want to know if the steam piston can be in a dewar also.  Anyone with experience fabing evacuated tubes speak up.

elliot

azuredu

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Mar 1, 2009, 2:06:42 AM3/1/09
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On Feb 28, 11:45 pm, "..." <offonoffoffon...@gmail.com> wrote:

> I read through the pdf and couldn't figure out what xiao was using for his
> reflectors? mylar? how did he avoid the crinkling problems we have?

Mylar. Crinckle? You mean when you apply the film on the substrate?
You have to acquire some experience, but that's not hard to avoid.
>
> I don't like the idea of having the steam engine mass produced in china.
> not that i'm against global trade or anything. I think one can be fabed
> easily from a hard chromed hydraulic cylinder w/ piston which could be found
> scrapped. (now that i say that I'll have to stop by the scrap yard in san
> francisco and see what sort of hydraulic cylinder options are around). If
> we wanna sell 1,000s then lets build them in house.

That's very interesting. More details? Size, resistance, material,
pricing?

> I am very interested in evacuated tubes. Borosilicate is sold in long tubes
> of any diameter you want. I wouldn't know how to seal the ends (where the
> pipe comes out), but will keep my ears up. Once that is answered, I want to
> know if the steam piston can be in a dewar also. Anyone with experience
> fabing evacuated tubes speak up.

You cannot do the usual way. Totally evacuated tube is not a viable
option. Industrial people are experiencing huge troubles with the
permanent seal.

What I propose is a partial evacuation plus eventually filling the
space with heavy inert gas and special insulating materials. Consider
branching a low-capacity vacuum pump (or high performance vacuum
cleaner) to the insulating layer, and regenerate the partial
evacuation from time to time.

This allows you to use rubber/plastics sealings. You should know how
to do so. However, please read my article on closed parabolic troughs:
there is a crucial calculation on dimensions.

...

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Mar 3, 2009, 3:47:38 PM3/3/09
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That's very interesting. More details? Size, resistance, material,
pricing?

I don't have many details to give.  working hydraulic cylinders capable of containing well over our working pressure are on ebay for cheap, and would be even cheaper at a scrap yard.  these  can be found in large diameters with long stroke lengths, which is suited for steam (low rpm, long powerful strokes).  for instance, two cylinders with pistons for $50: http://cgi.ebay.com/2-Prince-Hyd-Hydraulic-Cylinders-Bore-3-Stroke-16_W0QQitemZ220368726360QQcmdZViewItemQQptZPneumatic_Hydraulic_Valves_Parts?hash=item220368726360&_trksid=p3286.c0.m14&_trkparms=72%3A1546%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A1%7C294%3A50

new seals, rings and gaskets would be needed.  I dont know what the requirements for them would be.

it would be best to wait for something with corrosion resistance.  I dont know what their usual use is, but cylinders hard chromed on the inside are available.  pulp mills have serious corrosion problems, and technology to match.  Without that, a carbon steel cylinder and piston could be electrolessley nickle plated and maintain tolerances for $300-$400 with an at home kit.  there may be cheaper alternatives.

The piston would need to be bolted to a heavy chasis with a flywheel, which could be fabricated by an amature.  http://www.istockphoto.com/file_thumbview_approve/2568700/2/istockphoto_2568700_steam_piston.jpg

this could be made from scrap material. $2/lb

I've never done this so i dont know what unexpected complications could arise.

Also, an ideal steam engine would be oiless.  And i dont know anything about that.


You cannot do the usual way. Totally evacuated tube is not a viable
option. Industrial people are experiencing huge troubles with the
permanent seal.

yes, i would not expect a permenant seal to work at all.  perhaps daily re-evacuation would be necessary.  depending on the rate of leakage, a molecular sieve type getter to absorb leakage air as well as off gassed material might be helpful.  just speculation.

What I propose is a partial evacuation plus eventually filling the
space with heavy inert gas and special insulating materials.

You know that evacuating a space has very little effect  on insulation capacity untill the mean free path of the gas particles is greater than the gap to be insulating.  my pysical chemistry book says that 1 atm of n2 has a mean free path of about 70nm, with a halving of pressure doubling the mean free path.  thus, for a small 1cm gap you need to evacuate to .07 atm before any noticable insulation took place.  minimum, half this pressure should be reached to be at all insulating.  vacuum pumps can do this, blowers/compressors cannot.  I dont know what quality seal you need to hold this vaccum.

a micro pore transparent aerogel or something would drastically reduce vaccum requirements.  but where are you going to get that?


This allows you to use rubber/plastics sealings.

Would an organic polymer/elastomer  withstand several hundred degrees celcius?  I suspect some inorganic silicone based seal  would be necessary.
 
You should know how to do so.

I imagine there are several ways to do this, some more effective than others.  I would think a flanged pipe with an inorganic seal around the outside radius of the flange would work.  I've seen reducing fitting type things that seal around the pipe and again around the glass used.


GEOD998

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Mar 4, 2009, 8:28:39 AM3/4/09
to Solar Turbine
hey guys,I've been trying to keep up with your progress,you're doing
great ,wanted to offer a little "real world" experience with the
hydralic cylinder idea.I own equipment and have wrestled with more
than a few hyd cyl in my time.The problem is rust.Even full of hyd
oil, water in a hydralic system vaporizes and can cause damage to the
cylinder bores.Maybe a sleeve of 316 or better grade stainless steel
could help.I realize that will probably(but not definately) rule out
using the piston that came with the cylinder,but you would have to
change the seal setup anyway,perhaps ceramic piston rings as used in
the hi-perf auto market?I'm not trying to discourage(quite the
opposite) but I cant see a chromed hyd cyl holding up to steam for
long without some mods like these.There are alot of impressive Hi
density plastics out there that have potential for sleeve material,and
that is what alot of the seals are made of in the newer hyd cyls,so
they will take the stress. Ive been rigging things out of scrap for a
lotta years,and with a little thinking and fiddleing it usually
works,despite what "they" say,lol. Keep up the good work,I'll try to
keep up...Geo


On Mar 3, 3:47 pm, "..." <offonoffoffon...@gmail.com> wrote:
> > That's very interesting. More details? Size, resistance, material,
> > pricing?
>
> I don't have many details to give.  working hydraulic cylinders capable of
> containing well over our working pressure are on ebay for cheap, and would
> be even cheaper at a scrap yard.  these  can be found in large diameters
> with long stroke lengths, which is suited for steam (low rpm, long powerful
> strokes).  for instance, two cylinders with pistons for $50:http://cgi.ebay.com/2-Prince-Hyd-Hydraulic-Cylinders-Bore-3-Stroke-16...
>
> new seals, rings and gaskets would be needed.  I dont know what the
> requirements for them would be.
>
> it would be best to wait for something with corrosion resistance.  I dont
> know what their usual use is, but cylinders hard chromed on the inside are
> available.  pulp mills have serious corrosion problems, and technology to
> match.  Without that, a carbon steel cylinder and piston could be
> electrolessley nickle plated and maintain tolerances for $300-$400 with an
> at home kit.  there may be cheaper alternatives.
>
> The piston would need to be bolted to a heavy chasis with a flywheel, which
> could be fabricated by an amature.http://www.istockphoto.com/file_thumbview_approve/2568700/2/istockpho...

...

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Mar 4, 2009, 1:00:26 PM3/4/09
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much thanks geo


 but I cant see a chromed hyd cyl holding up to steam for
long without some mods like these.

 
you think even a hard chrome lined cylinder would need a sleeve?  do you know, are sleeves generally replaceable? or do they get jammed in there, never to come out?
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