Posted by Bob F on April 1, 2009, 6:45 pm
Jim Wilkins wrote:
>> sno wrote:
> ...
> Back during the 70's crisis I attended a talk by several energy
> inventors, one of whom planned to seal solar collector pipes into
> uncoated fluorescent light bulbs and then evacuate them. It might be
> worth pursuing if you rolled or welded a bellows section into the pipe
> to absorb expansion. Personally I'd use rubber seals and a small
> vacuum pump so I could disassemble the tubes if necessary, or compare
> the performance of argon and CO2. Like everything else I do that's
> fine for experimenting but doesn't make a practical product.
> When I learned chemical glassblowing we used platinum wires for glass-
> metal seals. I know from trying it that iron seals into light bulb
> glass but I didn't have the means to experiment with the leakage
> rate.
Sounds sort of like the evacuated tube solar collectors in common use today,
except they use heat pipes to carry the heat to the end.
Posted by Bruce Richmond on March 27, 2009, 10:04 pm
> Bruce Richmond wrote:
> > There was this link for spray paint.
> >http://www.dampney.com/Products/Products.asp?ProductID=28
> I should have bookmarked it then. Have it now - thank you.
> > For increasing surface area of the tube to the working fluid, I seem
> > to remember seing inserts with a cross section like * that you could
> > slide inside a pipe. Might even be able to find a source for pipe
> > with them pre-installed. Would be best to slip a cold insert into a
> > hot pipe so they would have better contact for heat transfer.
> I'll dig around and see what I can find. I like the idea, but am
> beginning to think that I might try this thing out first with an empty
> tube just to see how that plays.
> One of the trade-off factors here is that the viscosity of air increases
> with temperature, and the air in this long narrow hot head will need to
> move /fast/. I do want to distribute the heat as efficiently as
> possible, but I don't want to waste power overcoming flow resistance.
> It'll be an interesting task to find the balance point...
> > Might be able to make a cheap vacuum tube out of a used fluorescent
> > light tube.
> I read that thread, too - but I think when I get to that point I'll just
> buy one of the tubes used in solar water heaters...
I didn't read about it in any thread. Guess it is just a fairly
obvious work around. The ones purposely made for the job would be
better if they aren't outragously expensive. The lights are pretty
thin and delicate.
> > While you may get the high temp you are looking for by focusing to a
> > 3/8" line on a 1" pipe, to heat the working fluid inside the pipe you
> > need as much area as possible hot. So the heat from that 3/8" strip
> > will flow out to the rest of the pipe, spreading the heat out and
> > dropping the temp. Might be better off not bringing it to such a
> > narrow beam to start off with.
> I've had that same thought - and what seems to make most sense is to set
> up the mounts (they're just U-bolts) for the tube so that the tube can
> be raised so that the focus is at the bottom of the tube, and lowered to
> the point where the focus is coincident with the center of the tube.
> > Putting a small reflector on the back side of the pipe would not only
> > reduce losses due to re-emission, if the beam is made a bit wider than
> > the pipe it could be used to heat the back side of the pipe.
> I'll file that one for more thought, but the current geometry won't let
> me do that (I'd need to raise the focus, which would complicate the
> construction.
> > I don't *know* that the ideas above will help but they might be worth
> > thinking about.
> Until I'm sure that it can't be further improved and still be built at
> reasonable cost, /everything/ is worth thinking about.
> Thanks!
> --
> Morris Dovey
> DeSoto Solar
> DeSoto, Iowa USAhttp://www.iedu.com/DeSoto/
Posted by harry on March 26, 2009, 8:06 pm
On Mar 23, 4:35 pm, "Lord Gow333, Dirk Benedict's newest fan!"
> Preferably cheap (naturally). I have several acres of brushland and a good
> source for broken wood pallet scraps so I'm considering a small scale
> biomass generating plant. The boiler I can handle (safely, if not
> "officially approved"), and I could build a piston engine but I imagine a
> turbine would be more efficient.
> Comments?
> Sources?
> I'm a flaming lunatic?
> LG
> --
> "The United States is like a giant boiler. When the fire is finally lighted
> under it, there is no limit to the power it can generate." - Winston
> Churchill
Well you ARE a lunatic. There is a firm iin the UK makes small steam
turbines called Turney Turbines. I don't believe you will have enough
fuel to make the project worthwhile. Small steam turbines are
incredibly inefficient too. I should invest in photovoltaic or
windmill if your site is suitable.
It's possibe to convert a centrifugal pump to a steam turbine. These
are very common in the UK where we use wet heatings sytems,
It's also possible to convert a motorcycle engine into a steam
engine. I did see something on the internet but I can't find it now.
XML site map
> ...
> Back during the 70's crisis I attended a talk by several energy
> inventors, one of whom planned to seal solar collector pipes into
> uncoated fluorescent light bulbs and then evacuate them. It might be
> worth pursuing if you rolled or welded a bellows section into the pipe
> to absorb expansion. Personally I'd use rubber seals and a small
> vacuum pump so I could disassemble the tubes if necessary, or compare
> the performance of argon and CO2. Like everything else I do that's
> fine for experimenting but doesn't make a practical product.
> When I learned chemical glassblowing we used platinum wires for glass-
> metal seals. I know from trying it that iron seals into light bulb
> glass but I didn't have the means to experiment with the leakage
> rate.