Cheapo concentrators from junk material?

 Anyone ever thought about using an old flurescent tube as
solar concentrator ?

Figure out a 60" transluscent glass tube coated with a
reflective material (mylar ?) on the half of its diameter and
a copper tube running in the middle with no vaccum or
complicated device. I guess these concentrators could be
easily mounted in series for a very decent price.

Of course a spherical reflector is not as good as a parabolic
reflector, but I think it could make a substancial difference
from having no reflector at all. And it could collect light
for a slightly longer period of time during the day.

  david.williams@bayman.org (David Williams) wrote in


Thanks.

Here is some data from Wikipedia regarding the toxicity of
fluorescent lamps:


"The disposal of phosphor and particularly the mercury in the
tubes is an environmental issue. Mercury poses the greatest
hazard to pregnant women, infants, and children. Governmental
regulations in many areas require special disposal of
fluorescent lamps separate from general and household wastes.
For large commercial or industrial users of fluorescent
lights, recycling services are available in many nations, and
may be required by regulation. In some areas, recycling is
also available to consumers. The need for a recycling
infrastructure is an issue with instituting proposed bans of
incandescent bulbs.

The amount of mercury in a standard lamp can vary
dramatically, from 3 to 46 mg.[19] Newer lamps contain less
mercury and the 3-4 mg versions are sold as low-mercury types.
A typical 2006-era 4 ft (122 cm) T-12 fluorescent lamp (i.e.,
F32T12) contains about 12 milligrams of mercury.[20] In early
2007, the National Electrical Manufacturers Association in the
US announced that "Under the voluntary commitment, effective
April 15, 2007, participating manufacturers will cap the total
mercury content in CFLs under 25 watts at 5 milligrams (mg)
per unit. CFLs that use 25 to 40 watts of electricity will
have total mercury content capped at 6 mg per unit."[21]

A broken fluorescent tube is more hazardous than a broken
conventional incandescent bulb due to the mercury content.
Because of this, the safe cleanup of broken fluorescent bulbs
differs from cleanup of conventional broken glass or
incandescent bulbs. 99% of the mercury is typically contained
in the phosphor, especially on lamps that are near their end
of life.[22] Fluorescent lamps manufactured many decades ago
had phosphors that contained beryllium, which is toxic. One is
not likely to encounter lamps this old."

 O Solar Mio wrote:

   I don't see this as being affordable or practical. You will need a
lot of copper tubes as the "reflector" is so small and inefficient
(circular and you have the glass losses also). Copper is very expensive,
much more so than any reflector.

   Consider a higher concentration ratio with a larger reflector to
absorber ratio.

   Cutting ribs for a parabola is not hard, and aluminum flashing is
cheap and easy to bend. But you'll need a mirror finish. You may wish to
consider this:

http://www.irinfo.com/polish/html/polish.html


   Jeff

 

You bring two very dissuasive points:
-Copper is becoming more and more expensive.
-A lot of copper would be needed.

But yet I just found something interesting for those
interested with reflective tubes. There was a similar concept
developped Corning Glass Works in the 70's. There was three
major differences with my idea:
-A vacuum was created inside the tube.
-Two tubular glass collectors were used instead of a single    
copper collector.
-A thermo-reflective film was placed inside the tube to keep
heat inside.

Description here:
http://lnk.nu/osti.gov/l7g.jsp

Drawing here:
http://cjoint.com/?ggwjKkC5yD

 On Jun 5, 3:59 pm, david.willi...@bayman.org (David Williams) wrote:

One of the better "junk" solar concentrators that I have seen ar the
old, first generation satellite dishes lined with reflective mylar.
Real estate agents frequently want to get rid of them, and you can
have them for the cost of hauling it away. Try looking in craigslist
for starters.-Jitney