PLANS FOR 1995
Much of the program of work for this solar season is a logical continuation of prior developments. The new solar collector and new steam engine will warrant extensive testing. Also we hope to spend more time on refrigerator testing, both to gain a larger spectrum of results, and because of the potential importance of this technology, given the absence of electricity in many parts of the world needing refrigeration. During June and July, Prof. and Mrs. Vanek expect to be absent from Ithaca. At other times, visitors are welcome, by appointment. Steven Vanek will be in the field this summer. He hopes to teach some of the S.T.E.V.E.N. technologies at the Meadow Creek Education and Retreat Center in the Ozark mountains of Arkansas, where he will be an energy intern. Steven may pursue solar- related interests in the southwest United States later in 1995. Anyone in that area who is interested in a visit from S.T.E.V.E.N. Foundation should get in touch with Ithaca.
NEWS FROM THE FIELD
Two S.T.E.V.E.N. trainees of previous years are presently at work in Africa. Fr. Bert Otten, SJ, who visited here in July 1994, is now assisting at the Kasisi Center near Lusaka, Zambia. Not having heard from Fr. Bert, we suppose he is very busy helping meet the technology needs of the people of that region. Janet Hackert, Maryknoll lay missionary and former Cornell grad student, has returned to her work in Mugumu, Tanzania. Janet writes that one focus of her work with women's groups there is the introduction of fuel-saving cooking stoves (not solar powered but needing much less wood fuel), a design she worked on while here. Mark or "Moth" of Philadelphia is continuing development work with his "Bamboo Solar" group in Grenada, West Indies. While in Philadelphia he addressed the problem of setting up a parabolic solar collector in an urban setting where a support frame cannot be planted into the earth. His ingenious and good-looking solution is shown in the photo. Martin Adams, who visited here in summer 1993 and now conducts the Ananda Sevaka Centre for Ecology and Alternative Technology near Nicosia, Cyprus, in a recent newsletter displays a photo of a S.T.E.V.E.N. steam engine in process of contruction. M. Julia Carrera returns to her work with the people of Huamanchacona, high in the Peruvian Andes, transferring technologies including pumping and our solar oven. In January 1995 Prof. and Mrs. Vanek visited the SIFAT (Servants in Faith and Technology) in Alabama, a center for training Christian missionaries in simple technologies. Having learned about their projects and missions and having shared all our technologies, with the possibility of teaching them, we look forward to fruitful cooperation.
PEDAL-POWERED WASHING MACHINE
Furthering our research in the area of human-powered technologies (as opposed to alternate energy powered), Francis Vanek designed and built a pedal-powered washing machine in January. This device combined an old bicycle frame and the basin from a discarded toploader washing machine, mounted on a wooden stand with a connecting rod between one of the bike pedals and the agitator transmission which twists the agitator back and forth when the rider pedals the bike. Originally the hope was to have variable speeds and a spin cycle for spinning water out of the clothes after washing. While these features could not be added in with the time available, a semester of washing clothes in the apartment in Philadelphia showed that even this simple prototype could do an adequate job on a load of wash. The machine has now returned to Ithaca for display in the Foundation's collection. Such a device might be useful not only in LDC's where pedal- powered washing could reduce the work-load and improve hygiene, but also in advanced countries for people who want to exercise and do some practical housework at the same time.
TEN YEARS OF S.T.E.V.E.N. FOUNDATION
Look what happened while we were too busy to think about it--S.T.E.V.E.N. Foundation is in its tenth year of existence! The foundation was in fact incorporated in January 1986, and granted tax-exempt status as a philanthropic organization soon thereafter. However, solar-related work by Prof. Jaroslav Vanek goes back to about 1979, and a number of missions promoting what have become the S.T.E.V.E.N. technologies were undertaken in the early 1980's, notably to the San Luis Valley of Colorado in 1983, and an around-the-world mission to Africa (Kenya/Sudan), India and Philippines in 1984. Perhaps the tenth anniversary in early 1996 will provide the moment for a fuller story of S.T.E.V.E.N. Foundation.
DETAILS OF TECHNOLOGY UPDATE
**New size collector. partly because of materials availability, we have
now built a larger collector based on three 10 x 4 foot reflectors. First
measurements indicate some 7 kW of steam delivery, but we will verify further.
Because of difficulty to insert the three mirror with only 4 supports of
2 x 4's (see instructions for old collector) we now added 3 additional
2 x 4's to support each reflector in the middle, so that the two end parabolas
now are spanned by 7 10-foot 2 x 4's. Also it is desirable to reinforce
the southern end of the collector with additional angle irons running from
the bottom of the parabola and the angles holding the axis to the ends
of the suspension angles. This reinforces considerably the whole collector
and prevents bending (over time) of the lower end of the trough. It is
also very desirable to use strong wires and turnbuckles in bracing the
collector diagonally1) between the corners of the collector and 2) across
the rectangle formed by the boiler and the parallel bottom of the trough.
Concerning the sheet metal plates, we discarded 26 or 28 guage softite
galvanized sheets and find best the 24 guage which is more rigid and does
not form the folds/breaks as do the thinner 26/28 guage materials. [Illustration
1 here in hardcopy newsletter: steam engine overview] **Steam engine developments.
While the original injection and steam control valves are still very good,
we have started using valve seals based on ballbearing balls of various
sizes, which close a seat either formed by a polished bushing or formed
by drilling a larger hole over a smaller one concentrically. The opening
of the valve is then performed by poking from below with a poker sealed
in the valve through thick rubber tubes or silicone. Using such valves
we have constructed new steam engines, withstanding higher pressures. It
is such pressures that we want to slowly introduce going from a range of
10/20 to 100/200 pounds, hoping to attain higher efficiencies. We plan
to use glass protection for the boilers and even vacuum and perhaps less
than 3" boilers with continuous feeding of water during engine operation.
We hope to report more on this in later newsletters. [Illustration 2 here
in hardcopy newsletter: steam engine closeup] The essence of tthe new engine
is its separability. The entire mechanical portion is now reduced to a
rocking platform on top of which we mount any heat-resistant smooth cylinder
with piston and shaft moving parallel to the walls of the cylinder. The
accomodation to the motion of the crank is performed by the rocking motion.
And the rocking motion in turn opens and closes the ball-bearing seal valves
at the bottom of the platform. The great advantages are simplicity, directness
of motion of piston allowing higher pressures, and much longer stroke --
as long as permissible by the distance between the platform and the crankshaft.
The separability can best be understood in the following way. Anyone can
build his pump, electric generator or other application with a suitable
flywheel and crank-eccentric; even providing a pipe and corresponding piston
and then use a standard rocking platform, producible or purchasable from
a specialized coop or individual firm which can produce a series of such
machines. We hope to send such and instrument, not larger than a 7" cube
-- to the US southwest for a 550' deep well pump. The power takeoff may
involve a 6' diameter flywheel based on a side of a large cable-spool,
with bricks fastened to its perimeter.
** Mirror gluing. Those of you who have constructed your reflector
using the much less expensive nongluing mirror-plastic with oil- based
vaccum adhesion may have experienced some blistering on the mirror. To
avoid this there are several peices of advice: 1. Use non-outgassing oil
for adhesion, such as oil for use in vacuum pumps, which can be purchased
for a vew dollars. For $4 we bought a quart, enough for perhaps 100,000
sq.ft. of collector. 2. When one seals the edge of the mirrrors with a
water repellant tape (We have used most successfully electricians tapes),
at the corners where tapes cross eachother there remain microscopic passages
under the tapes. These must be sealed by silicone or other adhesive so
that no air can enter under the plastic. 3. Never crumple the plastic mirror
as this can form point-cracks in it. In general one must avoid even the
smallest holes on the plastic not to lose the vacuum. If such holes occur,
they must be closed perfectly, using silicone or the same tape used for
the mirror edges. [Illustration 3 here in hardcopy newsletter: solar icemaking
setup]
**Test of solar refrigeration. The icemaking test
of the STEVEN solar refrigerator in August 1994 used the generator and
evaporator, with a gas duct and shutoff valve between them. Our 8-foot
prototype generator had been filled with 2.57 kg calcium chloride (dried
in an oven for 5 hours at 120 degrees celsius), and later charged with
2.61 kg ammonia. The test was run on the 7th of August, an exceptionally
clear day in Ithaca, NY. The generator was heated using the collector from
11:15 AM to 4:00 PM. At 11:35, as pressure in the generator exceeded 200
PSI, the valve to the evaporator was opened and gaseous ammonia started
to flow. In the absence of an underground tank for condensation, the evaporator
was cooled by changing a water bath. Peak temperature of the generator,
measured with a thermocouple, was 138 degrees celsius at 1:56 PM. As gaseous
ammonia was being driven off, pressure in the generator remained between
150 and 215 PSI. On cooling in the afternoon, pressure in the generator
approached 100 PSI, approximately the vapor pressure in the generator approached
100 PSI, approximately the vapor pressure of liquid ammonia at the temperature
of the evaporator, and so the valve between evaporator and generator was
closed. Allowing this to remain open would have started the evaporation
or refrigeration part of the cycle. During the generation part of the cycle
1.95 kg of ammonia was driven off from the calcium chloride, very close
to the expected maximum of 3/4 of the original 2.61 kg of ammonia (6 out
of the 8 molecules of ammonia per calcium chloride driven off.). [Illustration
4 here in hardcopy newsletter: photo of solar icemaking setup] At 10 PM
we began the cooling portion of the cycle, with ammonia being reabsorbed
by the calcium chloride. Outside air temperature and the starting temperature
of the system was 17 deg C (63 deg F). The valve between evaporator the
generator was reopened, and through the walls of the pipe the sound of
boiling liquid ammonia and flowing gaseous ammonia could be heard. The
pipes of the evaporator were surrounded by a bath of 3.1 kg liquid water;
we hoped to freeze at least this amount of water. The temperature of the
water fell from 18 degrees celsius to the freezing point within 75 minutes
of the evaporator-generator valve being opened, at which point much of
the water had turned to slush. By 7:30 the next morning a block of ice
surrounding the evaporator bottles had formed. Total ice produced was 2.8
kg. (More detailed documents describing this refrigerator and its testing
are available by contacting S.T.E.V.E.N. Foundation.) [Illustration 5 here
in hardcopy newsletter: photo of 6 lb. solar ice]
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