re: optical concentration of solar energy
15 apr 1996
david jones wrote:
>...does anyone know of a source for a magnifying lens to concentrate sunlight
>in a straight line, instead of the usual circular form.
edmund scientific and 3m sell cylindrical lens material, but for a large area,
perhaps a linear parabolic reflector would be less expensive, eg this solar
greenhouse and water heater that might be built quickly for less than $1,000
in materials to provide winter space heating and domestic hot water and fresh
vegetables and flowers for a nearby home or the urban building or swimming
pool underneath a flat roof.
<- s. . 12'
. (32' long) . | z
/ .| /
. / . /
x <...........................f............. ---
water trench->. .
the reflective sheathing might be screwed to 16' kerfed 2 x 4s bent into a
4.5:1 concentrating parabolic shape, with the reflective surface inside the
greenhouse. this reflector would have a focus at about f=2.68' (y^2 = 4fx).
howard reichmuth, pe, designed the ecotope greenhouse, a similar structure
built 20 years ago near seattle. he's built several steam generators with
concentration ratios of 5 or 6. his advice: "don't stand in the focus.
i almost melted a pair of boots."
us patent number 4,129,120, expired 12/12/95, inventor norman saunders, pe,
describes an efficient concentrating steam generator using a flat transparent
boiler with a dark grate inside, just under the water surface. copies of us
patents can be obtained for $3 each from the superintendent of patents and
trademarks, washington, dc 20231.
> the idea is to use for domestic heating and/or energy generation a
>linear shaped lens to concentrate solar energy on a pipe where the focus
>of the lens corresponds to the shape of a pipe ie. a line of focused
>sunlight instead of a spot.
duffie and beckman's _solar engineering of thermal processes_, 2nd edition,
wiley, 1991, covers the design of these and other _non-focusing_ winston cpcs,
concentrators which accept all light coming from within a certain beamwidth...
>i would guess this to be a cheap item to produce if someone is doing it...
richard komp is doing it at sunwatt, rr 1, box 7751, jonesport me 04606,
207-967-5945. his hybrid 2:1 concentrating solar panels produce 150 watts
of electric power and 1600 watts of water heating power simultaneously,
rounding up half the usual number of photovoltaic suspects.
> i live in texas and have an abundance of sunlight for most of the
>year, so would like to experiment with saving energy and money.
hey, c'mon over to the renewable and alternative energy conference in abilene
from 4/22-23, where i'll be holding forth on solar closets and sunspaces for
house and water heating. the cost is only $40 to cover meals. call johnnie
lou avery at 915-235-7332, or send her a check at texas state technical
college, 300 college drive, sweetwater, tx 79556.
or come to roland winston's concentrator workshop in philadelphia on 5/3,
from 10:30-3 pm. $50/person by 4/22, ($15 for students, not including lunch.)
send your checks or faxes with credit card numbers to kathleen deluca at
the franklin institute, benjamin franklin parkway at 20th street, phila, pa
19103-1194, fax 215-448-1364. mike nicklas, aia, bill marshall, nrel,
robert bickmire, institute for energy conversion and morton h. lerner,
engineering consultant will also be there.