At the writing of this entry, the
solar Ghana exchange team has already been working on its design for a solar
reflector to make adinkra ink for over half of a semester. Up until this point
most of our recorded activity has been made up of sketched out designs,
modifications and materials lists. It is equally important to record our
experiences in a less technical yet detailed account that can be of use to
future exchange groups and student project groups. This blog may also serve as
a newsletter in the time that we are abroad.
The solar Ghana exchange team is
made up of six people; two students who have already been to Ghana and four
students that will be going this year. Samuel Pozorski and William Keddy-Hector
are the veteran RPI-Ghana exchange students of this group and so far their
experience has been invaluable in determining the feasibility of the new
project and modifying it. Jenna Hastings, Nate Radomski, Claudia Anzini and I
will be going abroad to implement the systems designed this semester in the
summer.
The RPI-Ghana Exchange program has
been going on for several years now and in the past there have been a number of
projects completed in Ghana under Professor Ron Eglash of Rensselaer
Polytechnic Institute (of which we are all students of). This year there will
also be two other projects completed by students from this institute on
information technology for education and HIV prevention. All of the projects
will be completed at Kwame Nkrumah University of Science and Technology
(KNUST), in Kumasi, Ghana during the month of July.
In the past the solar designs
implemented by this program in Ghana have sought to find a solution to the
inefficiencies and externalities associated with the mass production of charcoal
in Ghana, but this years group has decided to focus exclusively on producing
Adinkra ink. This choice was primarily made because of the infeasible scale on
which the charcoal has been produced by past projects. Adinkra ink is used
extensively in traditional Ghanaian art and is generally very fuel intensive.
The ink is made by soaking the bark of the Badie tree (Bridelia Ferrungiaa) in
water and then boiling the mixture down to a useable form. In addition to the
inks use in Ghanaian art, it is also used as a medicine to treat diarrhea among
other things. A more detailed account of this process will follow as we learn
to make the ink ourselves.
The Solar Reflector
The original choice to use a solar
reflector instead of another device to achieve this result was made earlier on
by previous groups, but in comparison with the next closest emission free
system, a solar oven, the solar reflector is the more effective choice. This is
because a typical solar oven uses flat reflective surfaces that require the
light to travel different distances from different reflectors, some of which
allow more heat to transfer than others because of the varying distances. A
curved solar reflected like the one being used in this project directs all of
the light to the heating chamber from equal distances and is therefore more
efficient. I am unsure of the origin of the design choice as to what the people
of Ghana may or may not have asked for. Too often projects are developed in
countries like Ghana because an outsider feels that a particular system would
benefit them. Ideally, the people of Ghana would choose a system that they feel
would help them based on their need after being provided a number of options.
This would ensure that they would want to use the system and that it would
reflect the local’s immediate knowledge and experience. We respectfully
recognize that Ghana has as much if not more to teach us as we have to teach
them.
There are three main systems that
will need to be perfected in order for our solar reflector to work. The
reflector itself, the tracking system, and the heat exchange system. The
largest barrier to implementation is access to materials in country. Ensuring
in country access is important because a sustainably feasible solution must be
within the financial means of the general population, have no crippling
dependence on out of country materials that would limit supply, be simple and
robust enough for easy yet infrequent repairs, and be entirely transferable in
knowledge and practice to ensure that long-term support is not necessary.
The reflector system has all but
been provided by past exchange programs. The success of this summer project
rests on Will and Sam’s reflector system, which was implemented in country last
year. All but the reflective material is available in country, but it was
necessary at the time to rely on an external source in exchange for the added
efficiency. More than likely this years project will be locked into this same
issue, as there is already a stock of this reflective material provided by past
groups at KNUST. Hopefully this will not hinder the long-term feasibility of
this system.
In past years the solar reflector
systems have had to be manually manipulated to track the sun, but to a certain
degree this is not unreasonable, as fires that traditionally acted as a source
of heat also needed tending. There have been several attempts to automate this
system, but they generally have required a solar powered motor system that has
not been effective because of the level of torque and financial expense. Due to
negative reports and past experiences, it has been suggested by past teams that
we look into a gravity escapement system. Initially a freon tracking system
seemed plausible, but after it was priced out it seemed far less feasible and
even unreliable under certain circumstances. The gravity escapement system
seems far more effective and reliable as it could be built using bike parts.
Its largest barrier to implementation in the long run will likely be technical
understanding and/ or local acceptance of a new system. Basically, the gravity
escapement system will use a system of gears to track the sun through an
improvised clock. A further explanation of this system will follow as it is
developed.
The heating chamber has been our
primary focus the last few weeks. In the past the chamber has just been a tube
of the substance that needs heating with piping for input and output on either
end. In one of the first reflectors made in Ghana by this program prohibitively
expensive glass was used to insulate prohibitively expense copper tubing,
neither of which was available in country. In order to make the system more
efficient without the expense, we are hoping to put together a heat pipe that
will remove the ink making process from the original enclosed chamber. This
would be extremely helpful because on top of getting more energy out of the
reflector we would also be able to monitor the inks progress more easily, clean
the system more easily to prevent eventual clogs, and make a larger batch. More
details on this system will eventually be made available as kinks are worked
out. We are currently having some issues with material availability because the
movement of the reactor to track the sun requires that we use flexible tubing
of some kind and the exchange of heat in the heating vessel requires the
surface area and heat transfer equivalent of copper distillery piping. We may
be able to salvage something from junkyards in country, but the system is
currently dangerously close to being reliant on out of country sources.
Since our group has never worked in
country, with the exception of Sam and Will, it is difficult to really know for
sure what is available to us, but we are making progress and these systems will
develop productively as we continue to plan them out. The project will evolve
into an effective system as it continues to be developed.
Physical Implementation
Currently,
all of the support pieces are cut out for the reflector system except for the
reflector sheet’s rib system, which may be altered slightly. The only
difference to our work on the frame in country will be that we will cut the
majority of the steel by hand. As of April 3rd we have all had a
chance to arc weld with the system that we purchased recently. The frame will
be welded together within a matter of weeks on top of the designing we are
doing on the other systems.
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